Substituted thienopyrans as antihypertensive agents

Abstract: Substituted thienopyrans and processes for preparing the thienopyrans are disclosed. The thienopyrans are useful as antihypertensive agents; antianginals are peripheral antivasoconstrictive agents.

Description: This is a continuation-in-part of application Serial No. 249,043, filed September 23, 1988. Field of the Invention The present invention relates to substituted thienopyran derivatives of the formula: and R₁ and R₂ are selected from the group consisting of hydrogen, nitro, cyano, trifluoromethyl, halogen such as bromo, chloro, iodo, alkyl (C₁₋₄), acyl (C₂₋₄), substituted acyl (C₂₋₄) (wherein the substituent is halogen such as bromo, chloro, fluoro or iodo), benzoyl, substituted benzoyl (wherein the substituent is halogen such as bromo, chloro, iodo, alkyl (C₁₋₄), alkoxy (C₁₋₄), acyl (C₂₋₄), nitro, cyano or trifluoromethyl), alkoxy(C₁₋₄)carbonyl, CHO, COOH, CONH₂, CON(R)₂ wherein R is alkyl (C₁₋₄), NHCOR wherein R is alkyl (C₁₋₄), alkoxy (C₁₋₄), phenyl or substituted phenyl [wherein the substituent is halogen such as bromo, chloro, iodo , lower alkyl (C₁₋₄), lower alkoxy (C₁₋₄), nitro, cyano, trifluoromethyl or lower acyl (C₁₋₄)] R₃ and R₄ are selected from the group consisting of hydrogen, acyl (C₂₋₅), substituted acyl wherein the substituent is CN or CF₃ lower alkyl (C₁₋₄), cycloalkyl (C₃₋₆), cycloalkyl carbonyl (C₃₋₆), pyridyl carbonyl, benzoyl, substituted benzoyl [wherein the substituent is halogen such as bromo, chloro, iodo, lower alkyl (C₁₋₄), lower alkoxy (C₁₋₄), lower acyl (C₂₋₄), trifluoromethyl, nitro, cyano RCONH wherein R is alkyl (C₁₋₄)] or R₃R₄N together may form a heterocyclic ring such as a pyrrole, pyrrolidine or piperidine ring or a lactam having 3-9 carbon atoms, including isoindolones, or a glycine anhydride; R₅ is hydrogen or together with R₆ forms a double bond; R₆ is hydrogen, hydroxy, alkoxy (C₁₋₆), acyloxy (C₂₋₇), benzoyl, substituted benzoyl (wherein the substituent is halogen such as bromo, chloro, iodo, lower alkyl (C₁₋₄), lower alkoxy (C₁₋₄), lower acyl (C₂₋₄), nitro, cyano or trifluoromethyl); and R₇ and R₈ are hydrogen or alkyl (C₁₋₄) and together may form a ring having 5-8 carbon atoms; and optical isomers thereof. The substituted thienopyran derivatives are relaxants of smooth muscle tone and as such have utility in vascular tissue for the treatment of hypertensive disease, angina and other vascular disorders characterized by poor regional perfusion (e.g. Raynaud's disease). Other possible utilities include bronchodilation, uterine relaxation, gut motility disorders, alopecia, asthma and treatment of incontinence. These compounds also are intermediates in the preparation of agents having similar pharmacological properties. Description of the Prior Art European Patent Application No. 120 426 describes substituted benzopyrans useful as antihypertensive agents having the following formula: European Patent Application No. 139992 describes substituted benzopyrans useful as antihypertensive agents having the following formula: European Patent Application No. 205 292 describes substituted pyrano [3,2-c] pyridine derivatives useful as antihypertensive agents having the following formula: British Patent No. 013786 describes pyrano [3,2-c] pyridine deravatives useful as antihypertensive agents having the following formula: Thiophene analogs of antiviral flavans having the following formula: are known in the art [Arch. Pharm. (Weinheim) 318 , 70 (1985)]. Thiophene isosteres of flavones and xanthones having the following formula: are also known in the art [Tetrahedron, 33 , 191 (1977)]. Detailed Description of the Invention The invention in its broadest aspects relates to substituted thienopyrans which are useful as antihypertensives. Several of the intermediates used to make the thienopyrans are also novel compounds and are considered to be part of the invention. The substituted thienopyrans of this invention are prepared as outlined in Scheme 1. As can be seen from Scheme 1, 3-methoxythiophene ( 1 ) prepared from 3-bromothiophene [S. Gronowitz, Arkiv. Kemi., 1958 , 12, 239], is treated with 3,3-disubstituted acryloyl chloride and a Lewis acid catalyst such as tin (IV) chloride, ferric chloride, zinc chloride or the like in an inert solvent such as methylene chloride, chloroform or THF at 0-25° C for 1-24 h to give the unsaturated ketone derivative 2 . The methoxy group on 2 is cleaved by the action of agents such as boron trifluoride, boron tribromide, boron trichloride, pyridinium hydrochloride or trimethylsilyl iodide in an inert solvent such as methylene chloride or chloroform at -20 to 20°C to give the alcohol 3 . Treatment of 3 with protic acids such as p -toluenesulfonic acid in an inert solvent such as benzene, toluene or the like at reflux temperatures gives the 5,5-disubstituted thieno[3,2-b]pyran-7-one 4 . Reduction of the ketone ( 4 ) by reducing agents such as sodium borohydride, lithium aluminum hydride or the like in suitable solvents such as alcohols or THF yields the alcohol 5 . Dehydration of 5 under acid conditions ( p -toluenesulfonic acid, for example) at -20 to 20°C with molecular sieves in an inert solvent such as dichloromethane, THF or benzene to remove water gives the olefin 6 . Alternatively, the ketone ( 4 ) may be reduced and the crude, unisolated alcohol ( 5 ) may be directly converted to the olefin ( 6 ) under similar conditions. Conversion of the olefin ( 6 ) to the bromohydrin ( 7 ) is accomplished by the action of N-bromosuccinimide and water in solvents such as DMSO or DMF at 0 to 50°C. The bromohydrin ( 7 ) is used generally without isolation and treated with bases such as sodium hydride or sodium hydroxide in solvents such as DMSO or DMF at -20 to 20°C to form the unstable epoxide ( 8 ). Alternatively olefin 6 can be converted directly to the epoxide ( 8 ) using peracids such as m-chloroperbenzoic acid or pertrifluoroacetic acid in solvents such as aliphatic alcohols or dichloromethane. Anions of amine or amide derivatives are prepared in situ by treating various amines such as pyrrolidine or piperidine or amides such as pyrrolidinone, piperidinone, caprolactam, benzamide and substituted benzamides such as p -nitrobenzamide with sodium hydride in solvents such as DMF or DMSO at room temperature. The epoxide ( 8 ) in solvents such as DMF, DMSO or the like is then treated with the thus-formed amine or amide anions at 0 to 20°C for 1-8 days to form 9 (R₁R₂ = H). Reaction of 9 with electrophiles such as bromine or nitric acid or the like gives the corresponding substituted thienopyran ( 9 ) wherein R₁R₂ = bromine or nitro, for example. When the electrophile is an acylating agent such as, for example, acetyl chloride or acetic anhydride and the reaction is carried out in the presence of a Lewis acid or protic acid catalyst at about -20 to 20°C for about 1 hour to 6 days, the product is the acyloxy derivative ( 10 ) (R₁R₂=H). Similar reactions with the appropriate electrophile under similar conditions produces the acyl acetate ( 10 ) (R₁ or R₂ = acyl, for example, acetyl). Reaction of the acetate 10 with methanolic sodium hydroxide or sodium carbonate at about 0-25°C for 1-24 hours yields 9 (R₁ or R₂=acyl, for example, acetyl). Reaction of 9 with bases such as sodium hydride in solvents such as THF, DMF or the like at 40-150°C for 1-16 hours produces enamine (9a). Alternatively, epoxide 8 is reacted with sodium azide in polar solvents such as DMF or DMSO at about -20 to 100°C to give azide 9 (NR₃R₄ = N₃). Reduction of the azide with typical hydride reducing agents such as lithium aluminum hydride or sodium borohydride in solvents such as diethyl ether, tetrahydrofuran or alcohols at about 0 to 100°C or with metals such as zinc or iron in acetic acid or dilute hydrochloric acid gives the corresponding aminoalcohol 9 (R₃,R₄ = H). Reaction of this amine with acylating agents such as acetyl chloride, benzoyl chloride or substituted benzoyl chlorides, for example, gives the compounds of the invention 9 wherein R₃ or R₄ is an acyl group such as acetyl, benzoyl or substituted benzoyl. Treatment of 9 (R₁ or R₂ =Br) with an organometallic agent such as palladium dichloride, bis(triphenylphosphine)palladium chloride or palladium diacetate in an alcoholic solvent such as methanol, ethanol or propanol in the presence of carbon monoxide at temperatures between 25-150°C gives 9 (R₁ or R₂ =CO₂R where R= Me, Et, Pr). Reactions of 9 (R₁ or R₂=CO₂R where R= Me, Et, Pr) with ammonia, ammonium chloride or ammonium hydroxide in an alcoholic solvent such as methanol, ethanol or propanol at a temperature between 0-50°C for 1-10 days gives 9 (R₁ or R₂ =CONH₂). Treatment of 9 (R₁ or R₂ = CONH₂) with dehydrating agents such as trifluoroacetic anhydride produces 9 (R₁ or R₂ =CN). The thieno[2,3-b]pyran compounds of this invention are prepared according to Scheme 2. As can be seen from the reaction scheme, 2,3-dibromothiophene ( 11 ) is converted by literature procedures [Tetrahedron, 1965 , 21, 3331] to 2-t-butoxy-3-bromothiophene ( 12 ). Compound 12 is then treated with t-butyl lithium followed by acylation with a 3,3-disubstituted acryloyl acid derivative such as the methyl or ethyl ester, acid chloride, anhydride or amide derivatives at about -70° to 50°C to give 13 . Removal of the t-butyl group and ring closure is done by heating 13 in an inert solvent such as benzene, toluene or xylenes in the presence of catalytic p-toluenesulfonic acid to give the 3,3-dimethyl-thienol[2,3-b]pyran-5-one ( 14 ). Compound 14 is brominated in an inert solvent such as methylene chloride, chloroform or THF at 0 to about 25°C for about 1-24 h to give the 7-bromo-3,3-dimethylthieno[2,3-b]pyran-5-one ( 15 ). Compound 15 is converted to the alcohol ( 16 ) using lithium aluminum hydride or sodium borohydride in solvents such as diethyl ether, THF or aliphatic alcohols at about 0 to 25°C. Dehydration of 16 gives the olefin 17 . Alternatively, the ketone 15 may be reduced and the crude, unisolated alcohol 16 may be directly converted to 17 under similar conditions. Conversion of 17 to bromohydrin 18 is accomplished by the action of N-bromosuccinimide and water in polar solvents. The bromohydrin is generally used without isolation and treated with bases to form the unstable epoxide 19 . Alternatively olefin 17 can be converted directly to the epoxide 19 using peracids such as m-chloroperbenzoic acid or petrifluoroacetic acid in solvents such as aliphatic alcohols or dichloromethane. Anions of amine or amide derivatives are prepared in situ by treating various amines such as pyrrolidine or piperidine or amides such as pyrrolidinone, piperidinone, caprolactam, benzamide and substituted benzamides such as p -nitrobenzamide with sodium hydride. Epoxide 19 is treated with the thus-formed amine or amide anions to form 20 (R₁ = Br, R₁ = H). Removal of the bromine on 20 followed by reaction with electrophiles such as nitric acid and the like gives the substituted compound 20 wherein R₁ or R₂ = nitro, for example. When the electrophile is an acylating agent such as acetyl chloride or acetic anhydride and the reaction is carried out in the presence of a Lewis acid or protic acid catalyst at about -20 to 20°C for 1 hour to 6 days, the product is the acyloxy derivative 21 (R₁ or R₂ = H). Further reaction under similar conditions produces the acyl acetate 21 (R₁ or R₂ = acyl, for example, acetyl). Reaction of 21 with methanolic sodium hydroxide or sodium carbonate at about 0-25°C for 1-24 hours yields the acyl compound ( 20 ) (R₁ or R₂ = acyl, for example, acetyl). Treatment of 20 (R₁ or R₂ =Br) with an organometallic agent such as palladium dichloride, bis(triphenylphosphine)palladium chloride or palladium diacetate in an alcoholic solvent such as methanol, ethanol or propanol in the presence of carbon monoxide at temperatures between 25-150°C gives 20 (R₁ or R₂ =CO₂R where R= Me, Et, Pr). Reaction of 20 (R₁ or R₂ =CO₂R where R= Me, Et, Pr) with ammonia, ammonium chloride or ammonium hydroxide in an alcoholic solvent such as methanol, ethanol or propanol at a temperature between 0-50°C for 1-10 days gives 20 (R₁ or R₂ =CONH₂). Treatment of 20 (R₁ or R₂ = CONH₂) with dihydrating agents such as trifluoroacetic anhydride produces 20 (R₁ or R₂ =CN). Alternatively, in a manner analogous to scheme 1, epoxide 19 is reacted with sodium azide to give azide 20 (NR₃R₄ = N₃). Reduction of the azide gives the aminoalcohol 20 (R₃,R₄ = H). Reaction of this amine with acylating agents such as acetyl chloride, benzoyl chloride or substituted benzoyl chlorides, for example, gives the compounds of the invention ( 20 ) wherein R₃ or R₄ is an acyl group such as acetyl, benzoyl or substituted benzoyl. The thieno[3,4-b]pyrans are prepared according to Scheme 3. In this reaction sequence, 3,4 -dibromothiophene is converted by literature procedures [Tetrahedron, 1965 , 21, 3331] to 3-bromo-4- t -butoxythiophene ( 22 ) which in turn is converted to 3-lithio-4- t -butoxythiophene according to the same literature procedure. Reaction of the 3-lithio compound with a 3,3-disubstituted acryloyl acid derivative such as the methyl or ethyl ester, acid chloride, anhydride or amide derivatives at about -70° to 50°C gives the unsaturated ketone derivative (23). Reaction of 23 with protic acid catalysts such as p -toluenesulfonic acid, sulfuric acid or the like at about 50-250°C neat or in inert solvents such as toluene or xylenes gives the ring-closed thieno[3,4-b]pyranone derivative ( 24 ). Bromination of 24 in a solvent such as methylene chloride, chloroform or THF at 0 to about 25°C for about 1-24 hours gives the 3-bromo-5,5-dimethylthieno [3,4-b]pyran-7-one (25). Using reaction conditions essentially as those described for Scheme 1, reduction of the ketone gives the alcohol 26 which is dehydrated to give the olefin 27 . Treatment of the olefin ( 27 ) with N-bromosuccinimide and water in polar solvents gives the bromohydrin 28 which is converted to the epoxide 29 . In a manner analogous to that described for Scheme 1, the epoxide 29 may also be reacted with sodium azide in polar solvents to give the azido alcohol 30 (NR₃R₄ = N₃). This azide is reduced with reducing agents such as hydrides or metals in protic acids to give the aminoalcohol 30 (R₃,R₄ = H). Reaction of this amine with acrylating agents such as acetyl chloride, benzoyl chloride or substituted benzoyl chlorides, for example, gives the compounds of the invention 30 wherein R₃ or R₄ is an acyl group such as acetyl, benzoyl or substituted benzoyl. Alternatively olefin 27 can be converted directly to the epoxide 29 using peracids such as m-chloroperbenzoic acid or pertrifluoroacetic acid in solvents such as aliphatic alcohols or dichloromethane. Reaction of 29 with the anions of various amines and amides gives the aminoalcohols 30 (R₁R₂ = H). Reaction of these derivatives with electrophiles such as bromine, chloride, sulfuryl chloride or nitric acid gives the substituted derivatives 30 (R₁ or R₂ = Br, Cl, NO₂), respectively. When the electrophile is an acylating agent such as acetyl chloride or acetic anhydride and Lewis or protic acid catalysis is employed, the product is the acetyl acetoxy derivative 32 (R₁ or R₂ = acetyl) which may be converted to the aminoalcohol 30 (R₁ or R₂ = acetyl) by treatment with alcoholic base. Those compounds wherein R₇,R₈ = cycloalkyl can be prepared by reacting a cyclic ketone with a Wittig phosphonium ylide reagent to form the 3,3-cycloalkylidine carboxylic acid which is the acrylic acid component of the starting material used to prepare those compounds wherein R₇₁,R₈=cycloalkyl. Reaction of 30 with bases such as sodium hydride in solvents such as THF, DMF or the like at 40-150°C for 1-16 hours produces the corresponding enamine. Treatment of 30 (R₁ or R₂ =Br) with an organometallic agent such as palladium dichloride, bis(triphenylphosphine)palladium chloride or palladium diacetate in an alcoholic solvent such as methanol, ethanol or propanol in the presence of carbon monoxide at temperatures between 25-150°C gives 30 (R₁ or R₂ =CO₂R where R= Me, Et, Pr). Reaction of 30 (R₁ or R₂ =CO₂R where R= Me, Et, Pr) with ammonia, ammonium chloride or ammonium hydroxide in an alcoholic solvent such as methanol, ethanol or propanol at a temperature between 0-50°C for 1-10 days gives 30 (R₁ or R₂ =CONH₂). Treatment of 30 (R₁ or R₂ = CONH₂) with dehydrating agents such as trifluoroacetic anhydride produces 30 (R₁ or R₂ =CN). Treatment of 32 as before with mild bases produces 31 . Reduction of 9 (Scheme 1, R₁ or R₂=NO₂) by catalytic hydrogenation using typical catalysts such as palladium on carbon in the presence of an acylating agent such as acetic anhydride, or benzoyl chloride, for example, in suitable solvents such as acetic acid, for example, yields 9 (R₁ or R₂=NHR, R=acetyl, benzoyl). In a similar fashion, the reduction of 20 (Scheme 2, R₁ or R₂=NO₂) and 31 (Scheme 3, R₁ or R₂=NO₂) yields the corresponding amide. Although the cis and trans isomers are formed during the reaction sequence, the product which is isolated is essentially the trans isomer. The compounds of this invention have antihypertensive activity as determined in spontaneously hypertensive rats (SHR). The compounds also have effects on potassium ion permeability changes within smooth muscle cells as determined in the Rb⁸⁶ efflux assay. [J. M. Smith, A. A. Sanchez and A. W. Jones, Blood Vessels, 1986 , 23, 297] Pharmaceutical compositions containing a compound of the present invention as the active ingredient in intimate admixture with a pharmaceutical carrier can be prepared according to conventional pharmaceutical compounding techniques. The carrier may take a wide variety of forms depending on the form of preparation desired for administration, e.g., intravenous, oral or parenteral. In preparing the compositions in oral dosage form, any of the usual pharmaceutical media may be employed, such as, for example, water, glycols, oils, alcohols, flavoring agents, preservatives, coloring agents and the like in the case of oral liquid preparations such as, for example, suspensions, elixirs and solutions ; or carriers such as starches, sugars, diluents, granulating agents, lubricants, binders, disintegrating agents and the like in the case of oral solid preparations such as, for example, powders, capsules, and tablets. Because of their ease in administration, tablets and capsules represent the most advantageous oral dosage unit form, in which case solid pharmaceutical carriers are obviously employed. If desired, tablets may be sugar coated or enteric coated by standard techniques. For parenterals, the carrier will usually comprise sterile water, though other ingredients, for example, to aid solubility or for preservative purposes, may be included. Injectable suspensions may also be prepared, in which case appropriate liquid carriers, suspending agents and the like may be employed. The pharmaceutical compositions will generally contain, dosage unit, e.g., tablet, capsule, powder, injection, teaspoonful, aerosol and the like, from about 0.1 to about 100 mg/kg and preferably from about 0.1 to about 20 mg/kg of the active ingredient. The following examples describe the invention in greater particularity and are intended to be a way of illustrating but not limiting the invention. Best Modes of Carrying out the Invention Melting point determinations were done on a Thomas Hoover capillary melting point apparatus and are uncorrected. All compounds had spectra (IR, ¹H NMR, MS) consistent with their assigned structures and were homogeneous by thin layer chromatography. ¹H NMR were determined on a Brucker WP-100 FT or a GE QE-300 spectrometer. MS were determined on a Finnigan Mat 8230 using desorption chemical ionization techniques. Silica Gel 60, 230-400 mesh, was used for both flash chromatography and medium pressure chromatography. EXAMPLE 1 3-Methoxy-2-(3-methyl-1-oxo-2-buten-1-yl)thiophene (2) A solution of 3-methoxythiophene (21.3 g, 0.187 mol) [S. Gronowitz, Arkiv. Kemi., 1958 , 12, 239] in dichloromethane (50 mL) was slowly added to a solution of 3,3-dimethylacryloyl chloride (22 mL, 0.195 mol) and tin(IV) chloride (23 mL, 0.195 mol) in dichloromethane (350 mL) at 0-5°C. After stirring at 0-5°C an additional 1 h, the solution was poured into ice water (1 L). The organic layer was separated, washed with water, and dried over magnesium sulfate. The solvent was evaporated in vacuo. The resulting oil was purified by flash chromatography using dichloromethane as the eluant to give the product, 29.6 g (81%): mp 49-51°C; IR (KBr): 1671, 1628 and 1430 cm⁻¹; MS: m/z 197 (MH⁺); ¹H NMR (CDCl₃): δ 1.98 (d, J=1.2 Hz, 3H), 2.23 (d, J=1.1 Hz, 3H), 3.98 (s, 3H), 6.85 (d, J=5.5 Hz,1H), 6.89 (dd, J = 1.1 Hz, J = 1.2 Hz, 1H) and 7.47 (d, J = 5.5 Hz, 1H). Anal. Calcd. for C₁₀H₁₂O₂S: C, 61.20; H, 6.16; S, 16.34. Found: C, 61.19; H, 6.17; S, 16.31. 3-Hydroxy-2-(3-methyl-1-oxo-2-buten-1-yl)thiophene (3) A solution of boron trichloride, (1.0 M in dichloromethane, 800 mL, 0.80 mol) was slowly added to a solution of 3-methoxy-2-(3-methyl-1-oxo-2-buten-1-yl) thiophene (52.3 g, 0.27 mol) in dichloromethane (400 mL) at -10°C to 5°C. The resultant solution was stirred an additional 1.5 h at -5°C. Ice water was added slowly with rapid stirring. The organic layer was separated, dried over sodium sulfate, and eluted through a pad of silica gel. The solvent was evaporated in vacuo and the resultant oil was crystallized from hexanes at -70°C to give the product, 40.0 g (82%), as a yellow solid: mp 32-33°C; IR (KBr): 1641, 1581 and 1541 cm⁻¹; MS: m/z 183 (MH⁺); ¹H NMR (CDCl₃): δ 2.00 (d, J=1.1 Hz, 3H), 2.30 (d, J=1.0 Hz, 3H), 6.25 (m, 1H), 6.75 (d, J=5.3 Hz, 1H), 7.37 (d, J=5.3 Hz, 1H) and 12.14 (s, exchanges with D₂O, 1H). Anal. Calcd. for C₉H₁₀O₂S: C, 59.32; H, 5.54; S, 17.59. Found: C, 59.35; H, 5.51; S, 17.62. 5,6-Dihydro-5,5-dimethyl-7H-thieno[3,2-b]pyran-7-one (4) A solution of 3-hydroxy-2-(3-methyl-1-oxo-2-buten-1-yl) thiophene (39.0 g, 0.214 mol) and p -toluenesulfonic acid (3.5 g, 18 mmol) in toluene (400 mL) was heated to reflux for 3.5 d. The resultant solution was washed with saturated aqueous sodium bicarbonate and dried over sodium sulfate. The solvent was evaporated in vacuo to give a brown oil, 38.62 g (99%). A portion of the resultant oil was purified for analysis by distillation in a Kugelrohr oven at 145 to 155°C at 0.35 mm Hg to give the product as an amber oil: IR (neat): 2979, 1664, 1530 and 1442 cm⁻¹; MS: m/z 183 (MH⁺); ¹H NMR (CDCl₃): δ 1.51 (s, 6H); 2.67 (s, 2H), 6.67 (d, J=5.4 Hz, 1H) and 7.60 (d, J=5.4 Hz, 1H). Anal. Calcd. for C₉H₁₀O₂S: C, 59.32; H, 5.54; S, 17.69. Found: C, 59.39; H, 5.53; S, 17.67. 5,6-Dihydro-7-hydroxy-5,5-dimethyl-7H-thieno[3,2-b]pyran (5) Sodium borohydride (0.97 g, 25.5 mmol) was added to a solution of 5,6-dihydro-5,5-dimethyl-7H-thieno [3,2-b]pyran-7-one (3.1 g, 17.0 mmol) in ethanol (50 mL) and stirred at rt for 2 h. An addition 0.97 g of sodium borohydride was added and the mixture was stirred 16 h. The mixture was poured into water and extracted with dichloromethane. The dichloromethane solution was washed with water (5x) and dried over magnesium sulfate. The solvent was evaporated in vacuo to give the product, 2.96 g (95%), as a brown oil: IR (neat): 3373, 2976, 1561 and 1400 cm⁻¹; MS: m/z 185 (MH⁺); ¹H NMR (CDCl₃): δ 1.34 (s, 3H), 1.45 (s, 3H), 1.87 (m, 1H), 1.94 (d, J=7.0 Hz, 1H, exchanged with D₂O), 2.16 (m, 1H), 4.88 (m, 1H), 6.57 (d, J=5.4 Hz, 1H), 7.13 (d, J=5.4 Hz, 1H). This oil was used without further purification in the next step. 5,5-Dimethyl-5H-thieno[3,2-b]pyran (6, Method A) A mixture of 5,6-dihydro-7-hydroxy-5,5-dimethyl-7H-thieno [3,2-b]pyran (1.3g, 7.06 mmol), p -toluenesulfonic acid (0.11 g, 0.58 mmol) and ground molecular sieves (1.3 g) was stirred at -5°C for 1.5 h. The mixture was washed with 1.0 N aqueous sodium hydroxide and dried over magnesium sulfate. The solvent was evaporated in vacuo to give the product, 1.17 g (99%), as a red oil: IR (neat): 2976, 1504 and 1531 cm⁻¹; MS: m/z 167 (MH⁺): ¹H NMR (CDCl₃): δ 1.45 (s, 6H), 5.27 (d, J=9.8 Hz, 1H), 6.30 (d, J=9.8 Hz, 1H), 6.60 (d, J=5.3 Hz, 1H) and 6.99 (d, J=5.3 Hz, 1H). This oil was used without further purification in the next step. 5,5-Dimethyl-5H-thieno[3,2-b]pyran (6, Method B) Sodium borohydride (3.27 g, 86.3 mmol) was added to a solution of 5,6-dihydro-5,5-dimethyl-7H-thieno [3,2-b]pyran-7-one (12.1 g, 66.4 mmol) in ethanol (100 mL) and the resultant mixture was stirred at rt for 17 h. The mixture was poured into water (400 mL) and extracted with dichloromethane (2 x 100 mL). The dichloromethane solution was washed with water (5x), dried over sodium sulfate, and filtered. Molecular sieves (12 g) and p-toluenesulfonic acid (1.2 g, 6.3 mmol) was added to the resultant solution and stirred at 0°C for 1.5 h. The reaction mixture was filtered, washed with saturated aqueous sodium bicarbonate in dried over sodium sulfate. The solvent was evaporated in vacuo to give the product, 11.0 g (99%), as a red oil which was identical in all respects to the product described in Method A. 6-Bromo-7-hydroxy-5,6-dihydro-5,5-dimethyl-7H-thieno[3,2-b] pyran (7) N-Bromosuccinimide (12.9 g, 72.5 mmol) was added in portions to a solution of 5,5-dimethyl-5H-thieno[3,2-b] pyran (10.95 g, 65.9 mmol) and water (1.6 mL, 89.5 mmol) in dimethyl sulfoxide (110 mL) at rt. The resultant solution was stirred at rt for 16 h poured into ice water (400 mL) and extracted into dichloromethane. The dichloromethane solution was washed with water (5x) and dried over sodium sulfate. The solvent was evaporated in vacuo and the residue was purified by flash chromatography using dichloromethane as the eluant to give the product, 11.5 g (66%), as a brown oil: Note that this oil is thermally unstable and decomposes within several hours at rt: ¹H NMR (CDCl₃): δ 1.44 (s, 3H), 1.60 (s, 3H), 2.56 (d, J=4 Hz, 1H, exchanges with D₂O), 4.10 (d, J=7 Hz, 1H), 4.98 (dd, J=4 Hz, J=7 Hz, 1H), 6.56 (d, J=5 Hz, 1H), 7.16 (d, J=5 Hz, 1H). This oil was used without further purification in the next step. 5,6-Dihydro-6-hydroxy-5,5-dimethyl-7-(2-oxopyrrolidin-1-yl)-7H-thieno[3,2-b] pyran Sodium hydride (60% in oil, 1.17 g, 29.3 mmol) was added to a solution of 6-bromo-7-hydroxy-5,6-dihydro-5,5-dimethyl-7H-thieno [3,2-b]pyran (7.0 g, 26.6 mmol) in N,N-dimethylformamide (115 mL) at 0°C. The resultant mixture was stirred at rt for 2 h. 2-Pyrrolidinone (6.1 mL, 79.8 mmol) was added to the solution followed by sodium hydride (60% in oil, 1.17 g, 29.3 mmol) and stirring was continued at rt for 4 days. The solution was poured into ice water (500 mL) and extracted with dichloromethane. The dichloromethane solution was washed with water (5x) and dried over sodium sulfate. The solvent was evaporated in vacuo and the resultant solid was triturated in diethyl ether to give the product, 3.91 g (55%), as a colorless solid: mp 154-155°C; IR (KBr): 3263, 1665 and 1562 cm⁻¹; MS: m/z 268 (MH⁺); ¹H NMR (CDCl₃): δ 1.30 (s, 3H), 1.50 (s, 3H), 2.07 (m, 2H), 2.52 (m, 2H), 3.00 (d, J=5.5 Hz, 1H, exchanges with D₂O), 3.35 (m, 2H), 3.78 (dd, J=5.5 Hz, J=9.0Hz 1H, simplifies to d, J=9.0 Hz, with D₂O), 5.28 (d, J=9.0 Hz, 1H), 6.57 (d, 5.4 Hz, 1H) and 7.11 (d, J=5,4 Hz, 1H). Anal. Calcd. for C₁₃H₁₇NO₃S: C, 58.40; H, 6.41; N, 5.24; S, 11.99. Found: C, 58.57; H, 6.47; N, 5.23; S, 12.03. EXAMPLE 2 5,6-Dihydro-6-hydroxy-5,5-dimethyl-7-(2-oxopiperidin-1-yl)-7H-thieno[3,2-b]pyran 6-Bromo-7-hydroxy-5,6-dihydro-5,5-dimethyl-7H-thieno[3,2-b] pyran (1.5 g, 5.7 mmol) and δ-valerolactam (1.7 g, 17.1 mmol) were treated with sodium hydride (0.50 g, 12.5 mmol) in N,N-dimethylformamide (25 mL) using the procedure described in Example 1 to give the product as a colorless solid, 0.681 g (43%): mp 151-152°C; IR (KBr): 3195, 1610 and 1563 cm⁻¹; MS: m/z 282 (MH⁺); ¹H NMR (CDCl₃): δ 1.29 (s, 3H), 1.49 (s, 3H), 1.81 (m, 4H), 2.53 (t, J=6.5 Hz, 2H), 3.15 (m, 1H), 3.24 (m, 1H), 3.68 (d, J=5.0 Hz, 1H, exchanges with D₂O), 3.79 (dd, J=5.0 Hz, J=9.1 Hz, 1H, simplifies to d, J=9.1 Hz with D₂O), 5.84 (d, J=9.1 Hz, 1H), 6.57 (d, J=5.4 Hz, 1H) and 7.11 (d, J=5.4 Hz, 1H). Anal. Calcd. for C₁₄H₁₉NO₃S: C, 59.76; H, 6.81; N, 4.98; S, 11.40. Found: C, 59.85; H, 7.05; N, 5.11; S, 11.26. EXAMPLE 3 5,6-Dihydro-6-hydroxy-5,5-dimethyl-7-(4-nitrobenzamido)-7H-thieno[3,2-b]pyran 6-Bromo-7-hydroxy-5,6-dihydro-5,5-dimethyl-7H-thieno[3,2-b]-pyran (6.8 g, 25.8 mmol) and 4-nitrobenzamide (10.7 g, 64.5 mmol) were treated with sodium hydride 60% in oil (2.26 g, 56.8 mmol) in N,N-dimethylformamide (110 mL) using the procedure described for the preparation of 5,6-dihydro-6-hydroxy-5,5- dimethyl-7-(2-oxopyrrolidin -1-yl)-7H-thieno[3,2-b]pyran. The reaction mixture was poured into water and extracted into 10% isopropanol in dichloromethane. The solvent was evaporated in vacuo and the residue was purified by medium pressure chromatography using 2% methanol in dichloromethane as the eluant to give the product, 4.5 g (50%), as a pale yellow solid: mp 183-186°C dec; IR (KBr): 3398, 1664, 1644 and 1601 cm⁻¹; MS; m/z 349 (MH⁺); ¹H NMR (CDCl₃): δ 1.35 (s, 3H), 1.50 (s, 3H), 3.79 (d, J=7.9 Hz, 1H), 4.26 (bs, 1H, exchanges with D₂O), 5.19 (d, d, J=7.9 Hz, and J=7.0 Hz, 1H), 6.59 (bd, J=7.0 Hz, 1H, shifts to 6.66 with D₂O), 6.63 (d, J=5.4 Hz, 1H), 7.18 (d, J=5,4 Hz, 1H), 7.97 (d, J=8.8 Hz, 2H) and 8.32 (d, J=8.8 Hz, 2H). Anal. Calcd. for C₁₆H₁₆N₂O₅S: C, 55.16; H, 4.63; N, 8.04; S, 9.20. Found: C, 55.45; H, 4.76; N, 8.25; S, 9.14. EXAMPLE 4 2-Bromo-5,6-dihydro-6-hydroxy-5,5-dimethyl-7-(2-oxopyrrolidin-1-yl)-7H-thieno [3,2-b] pyran A solution of bromine (0.20 mL, 3.92 mmol) in dichloromethane (5 mL) was slowly added to a solution of 5,6-dihydro-6-hydroxy-5,5-dimethyl-7-(2-oxopyrrolidin-1-yl)-7H-thieno[3,2-b]pyran (1.0 g, 3.74 mmol) at -5°C. The resultant mixture was stirred at rt for 2 h. The resulting precipitate was collected byfiltration and purified by medium pressure chromatography using 5% methanol in dichloromethane as the eluant to give the product as a colorless solid, 0.28 g (22%): mp 162-165°C; IR(KBr): 3287, 1666 and 1570 cm⁻¹; MS: m/z 346 (MH⁺); ¹H NMR (CDCl₃): δ 1.30 (s, 3H), 1.47 (s, 3H), 2.06 (m, 2H), 7.50 (m, 2H), 3.23 (bs, 1H, exchanges with D₂O), 3.34 (m, 2H), 3.76 (d, J=9.1 Hz, 1H) 5.16 (d, J=9.1 Hz, 1H) and 6.56 (s, 1H). Anal. Calcd. for C₁₃H₁₆BrNO₃S: C, 45.10; H, 4.66; N, 4.05. Found: C, 45.10; H, 4.40; N, 3.97. EXAMPLE 5 5,6-Dihydro-6-hydroxy-5,5-dimethyl-2-nitro-7-(2-oxopyrrolidin-1-yl)-7H-thieno [3,2-b]pyran Nitric acid (90%, 1.2 mL, 26.9 mmol) was added to a solution of 5,6- dihydro-6-hydroxy-5,5-dimethyl-7-(2-oxopyrrolidin-1-yl)-7H-thieno[3,2-b]pyran (1.0 g, 3.74 mmol) in acetic acid (30 mL) at 18°C, and stirred at rt for 1.5 h. The resultant solution was poured into ice water (200 mL). Within 10 min a yellow solid crystallized which was collected by filtration, washed with water and triturated in diethyl ether to give the product, 0.487 g (42%), as a yellow solid: mp 214-217°C; IR (KBr): 3216, 1655 and 1512 cm⁻¹; MS: m/z 313 (MH⁺); ¹H NMR (DMSO-d₆): δ 1.23 (s, 3H), 1.43 (s, 3H), 2.00 (m, 2H), 2.36 (m, 2H), 3.16 (m, 1H), 3.20 (m, 1H), 3.80 (d, J=9.5 Hz, 1H), 4.98 (d, J=9.5 Hz, 1H), 5.92 (bs, 1H, exchanges with D₂O) and 7.75 (s, 1H). Anal. Calcd. for C₁₃H₁₆N₂O₅S: C, 49.99; H, 5.16; N, 8.97; S, 10.27. Found: C, 49.70; H, 5.00; N, 8.65; S, 10.33. EXAMPLE 6 6-Acetoxy-2-acetyl-5,6-dihydro-5,5-dimethyl-5-(2-oxopyrrolid-1-yl)-7H-thieno [3,2-b]pyran A solution of 5,6-dihydro-6-hydroxy-5,5-dimethyl-7-(2-oxopyrrolidin-1-yl)- 7H-thieno[3,2-b]pyran (1.76 g, 6.58 mmol) and perchloric acid (70%, 10 drops) in acetic anhydride (15 mL) was stirred at 60°C for 2 h. The resultant brown solution was poured into ice water (100 mL) and the product was extracted into dichloromethane, washed with water (4x) and dried over sodium sulfate. The solvent was evaporated in vacuo and the resultant oil was purified by medium pressure chromatography using 1% methanol in dichloromethane as the eluant to give the product, 0.85 g (37%): mp 170-172°C; IR (KBr): 1755, 1690, 1666 and 1564 cm⁻¹; MS: m/z 352 (MH⁺); ¹H NMR (CDCl₃): δ 1.38 (s, 3H), 1.39 (s, 3H), 1.98 (m, 2H), 2.10 (s, 3H), 2.37 (m, 2H), 2.49 (s, 3H), 3.23 (m, 1H), 3.38 (m 1H), 5.14 (d, J=9.3 Hz, 1H), 5.47 (d, J=9.3 Hz, 1H) and 7.16 (s, 1H). Anal. Calcd. for C₁₇H₂₁NO₅S: C, 58.10; H, 6.02; N, 3.99; S. 9.12. Found: C, 57.76; H, 5.87; N, 3.69; S, 9.11. EXAMPLE 7 2-Acetyl-5,6-dihydro-6-hydroxy-5,5-dimethyl-7-(2-oxopyrrolidin-1-yl)-7H-thieno [3,2-b]pyran Aqueous sodium hydroxide (50%, 0.15 g, 1.87 mmol) was added to a solution of 6-acetoxy-2-acetyl-5,6-dihydro-5,5-dimethyl-7-(2-oxopyrrolidin-1-yl)-7H-thieno[3,2-b]pyran (0.45 g, 1.28 mmol) in methanol (20 mL) and stirred at rt for 1h. The solution was poured into water (100 mL) and extracted into dichloromethane. The dichloromethane solution was washed with water (3x) and dried over magnesium sulfate. The solvent was evaporated in vacuo and the resultant oil was crystallized from diethyl ether and hexanes to give the product, 0.327 g (83%), as a colorless solid: mp 102-106°C; IR (KBr): 1665 and 1561 cm⁻¹; MS: m/z 310 (MH⁺); ¹H NMR (CDCl₃): δ 1.31 (s, 3H), 1.51 (s, 3H), 2.07 (m, 2H), 2.48 (s, 3H), 2.51 (m, 2H), 3.34 (m, 2H), 3.45 (d, J=6.2 Hz, 1H, exchanges with D₂O), 3.80 (dd, J=6.2 Hz and J=9.4 Hz, 1H, simplifies to d, J=9.4 Hz, with D₂O), 5.29 (d, J=9.4 Hz, 1H) and 7.14 (s, 1H). Anal. Calcd. for C₁₅H₁₉NO₄S: C, 58.23; H, 6.19; N, 4.53. Found: C, 58.30; H, 6.31; N, 4.45. EXAMPLE 8 6-Acetoxy-5,6-dihydro-5,5-dimethyl-7-(2-oxopyrrolidin-1-yl)-7H-thieno[3,2-b]pyran A solution of 5,6-dihydro-6-hydroxy-5,5-dimethyl-7-(2-oxopyrrolidin-1-yl)-7H-thieno[3,2-b]pyran (2.0 g, 7.48 mmol) and perchloric acid (70%, 10 drops) in acetic anhydride (20 mL) were stirred for 1 h at 0-5°C. The solution was poured into ice water (100 mL). The product was extracted into dichloromethane, washed with water (4x), and evaporated in vacuo. The resultant oil was purified by flash chromatography, using 1% methanol in dichloromethane as the eluant, then crystallized from hexanes to give the product, 2.12 g (92%), as a colorless solid: mp 92-93°C; IR(KBr): 1745 and 1684 cm⁻¹; MS: 310 (MH⁺); ¹H NMR (CDCl₃): δ 1.37 (s, 3H), 1.38 (s, 3H), 1.98 (m, 2H), 2.10 (s, 3H), 2.37 (m, 2H), 3.24 (m, 1H), 3.40 (m, 1H), 5.15 (d, J=9.1 Hz, 1H), 5.44 (d, J=9.1 Hz, 1H), 6.58 (d, J=5.4 Hz, 1H) and 7.13 (d, J=5.4 Hz, 1H). Anal. Calcd. for C₁₅H₁₉NO₄S: C, 58.23; H, 6.19; N, 4.52; S, 10.36. Found: C, 58.11; H, 5.89; N, 4.31; S, 10.41. EXAMPLE 9 5,6-Dihydro-6-hydroxy-5,5-dimethyl-2-nitro-7-(4-nitrobenzamido)-7H-thieno[3,2-b]pyran 5,6-Dihydro-6-hydroxy-5,5-dimethyl-7-(4-nitrobenzamido)-7H-thieno[3,2-b]pyran (1.5 g, 4.30 mmol) was treated with 90% nitric acid (2.5 mL, 53.5 mmol) in acetic acid (25 mL) and stirred at 15-20°C for 0.5 h. The resultant solution was poured into ice water 100 mL and extracted with 10% isopropanol in dichloromethane. The dichloromethane solution was washed with saturated aqueous sodium bicarbonate and dried over magnesium sulfate. The solvent was evaporated in vacuo and the residue was purified by medium pressure chromatography using 2% methanol in dichloromethane as the eluant, to give the product, 0.489g (29%), as a yellow solid: mp 221-225°C dec; IR (KBr): 3345, 1647 and 1602 cm⁻¹; MS: m/z 394 (MH⁺); ¹H NMR (DMSO-d₆): δ 1.26 (s, 3H), 1.45 (s, 3H), 3.90 (dd, J=8.8 Hz and J=5.9 Hz, 1H, simplifies to d, J=8.8 Hz with D₂O), 4.98 (dd, J=7.6 Hz and J=8.8 Hz, 1H, simplifies to d, J=8.8 Hz with D₂O), 6.01 (d, J=5.9 Hz, 1H exchanges with D₂O), 7.75 (s, 1H), 8.14 (d, J=8.8 Hz, 2H) 8.37 (d, J=8.8 Hz, 2H), and 9.38 (d, J=7.6 Hz, 1H, exchanges with D₂O). Anal. Calcd. for C₁₆H₁₅N₃O₇S: C, 48.85; H, 3.84; N, 10.68. Found: C, 48.91; H, 3.62; N, 10.46. EXAMPLE 10 5,6-Dihydro-6-hydroxy-5,5-dimethyl-2-nitro-7-(2-oxopiperidin-1-yl)-7H-thieno[3,2-b]pyran The title compound was prepared as described in Example 5 starting with 5,6-dihydro-6-hydroxy-5,5-dimethyl-7-(2-oxopiperidin-1-yl)-7H-thieno[3,2-b]pyran (1.5 g, 5.33 mmol) and 90% nitric acid (2.5 mL) in acetic acid (25 mL) to give the product, 0.837 g (48%), as a yellow solid: mp 210-211 o C; IR (KBr): 3231, 1613, 1515 and 1492 cm⁻¹; MS: m/z 327 (MH⁺); ¹H NMR (CDCl₃): δ 1.32 (s, 3H), 1.51 (s, 3H), 1.84 (m, 4H), 2.55 (m, 2H), 3.20 (m, 2H), 3.84 (d, J=9.5 Hz, 1H), 4.78 (bs, 1H, exchanges with D₂O), 5.86 (d, J=9.5 Hz, 1H) and 7.40 (s, 1H). Anal. Calcd. for C₁₄H₁₈N₂O₅S: C, 51.52; H, 5.56; N, 8.58; S, 9.86. Found: C, 51.26; H, 5.25; N, 8.32; S, 9.86. EXAMPLE 11 2-Bromo-5,6-dihydro-6-hydroxy-5,5-dimethyl-7-(2-oxopiperidin-1-yl)-7H-thieno[3,2-b]pyran The title compound was prepared as described in Example 4 starting with 5,6-dihydro-6-hydroxy-5,5-dimethyl-7-(2-oxopiperidin-1-yl)-7H-thieno[3,2-b]pyran (1.4 g, 5.0 mmol) and bromine (0.27 mL, 5.2 mmol) in dichloromethane (30 mL). Purification by flash chromatography using 1% methanol in dichloromethane as the eluant and recrystallization from dichloromethane/hexanes gave the product, 3.87 g (78%), as a colorless solid: mp 200-202 o C; IR(KBr): 3442, 2942, 1616, 1571 and 1488 cm⁻¹; MS: m/z 360 (MH⁺); ¹H NMR (CDCl₃): δ 1.29 (s, 3H), 1.46 (s, 3H), 1.82 (m, 4H), 2.51 (m, 2H), 3.12 (m, 1H), 3.27 (m, 1H), 3.46 (d, J=5.0 Hz, 1H, exchanges with D₂O),3.78 (d,d, J=9.0 Hz, J=5.0 Hz,1H, simplifies to d, J=9.0 Hz, with D₂O), 5.74 (d, J=9.0 Hz, 1H) and 7.58 (s, 1H). Anal. Calcd. for C₁₄H₁₈BrNO₃S: C, 46.67; H, 5.04; N, 3.89. Found: C, 46.99; H, 5.05; N, 3.84. EXAMPLE 12 6-Acetoxy-2-acetyl-5,6-dihydro-5,5-dimethyl-7-(4-nitrobenzamido)-7H-thieno[3,2-b]pyran The title compound was prepared as described in Example 6 starting with 5,6-dihydro-6-hydroxy-5,5-dimethyl-7-(4-nitrobenzamido)-7H-thieno[3,2-b]pyran (1.5 g, 4.31 mmol), acetic anhydride (15 mL) and perchloric acid (70%, 10 drops) to give the product, 0.86 g (46%), as a pale yellow solid: mp 251-253°C dec; IR (KBr): 1753, 1670, 1655 and 1530 cm⁻¹; MS: m/z 433 (MH⁺); ¹H NMR (CDCl₃): δ 1.41 (s, 3H), 1.44 (s, 3H), 2.14 (s, 3H), 2.48 (s, 3H), 5.18 (d, J = 9.3 Hz, 1H), 5.40 (d,d, J = 8.3 Hz, J = 9.3 Hz, 1H), 6.83 (d, J = 8.3 Hz, 1H, shifts to d 6.91 with D₂O), 7.14 (s, 1H); 7.94 (d, J = 7.1 Hz, 2H), 8.30 (d, J = 7.1 Hz, 2H). Anal. Calcd. for C₂₀H₂₀N₂O₇S: C, 55.55; H, 4.66; N, 6.48; S, 7.41. Found: C, 55.34; H, 4.69; N, 6.44; S, 7.31. EXAMPLE 13 2-Acetyl-5,6-dihydro-6-hydroxy-5,5-dimethyl-7-(4-nitrobenzamido)-7H-thieno[3,2-b]pyran 6-Acetoxy-2-acetyl-5,6-dihydro-5,5-dimethyl-7-(4-nitrobenzamido)-7H-thienopyran (0.60 g, 1.39 mmol) was treated with aqueous sodium hydroxide (1N, 1.5 mL, 1.5 mmol) in methanol (10 mL) at rt and stirred for 2 h. The resultant solution was poured into water and extracted with 5% isopropanol in dichloromethane. The organic phase was washed with water (3x) and dried over magnesium sulfate. The solvent was evaporated in vacuo and the resultant solid triturated in diethyl ether to give the product, 0.36 g (66%), as a pale yellow solid: mp 223-225°C; IR (KBr): 1647, 1601, 1530 and 1458 cm⁻¹; MS: m/z 391 (MH⁺); ¹H NMR (DMSO-d₆): δ 1.23 (s, 3H), 1.42 (s, 3H), 2.45 (s, 3H), 3.84 (m, 1H, simplifies to d, J=8.9 Hz with D₂O), 5.01 (m, 1H, simplifies to d, J = 8.9 Hz, with D₂O), 5.86 (d, J = 5.9 Hz, 1H exchanges with D₂O), 7.47 (s, 1H), 8.14 (d, J=8.8 Hz, 2H), 8.36 (d, J = 8.8 Hz, 2H) and 9.27 (d, 1H, exchanges with D₂O). Anal. Calcd. for C₁₈H₁₈N₂O₆S: C, 55.38; H, 4.65; N, 7.18; S, 8.21. Found: C, 55.12; H, 4.63; N, 6.93; S, 8.11. EXAMPLE 14 7-(4-Chlorobenzamido)-5,6-dihydro-6-hydroxy-5,5-dimethyl-7H-thieno[3,2-b]pyran The title compound was prepared as described in Example 3 starting with 6-bromo-7-hydroxy-5,6-dihydro-5,5-dimethyl-7H-thieno[3,2-b]pyran (4.75g, 18.1 mmol) and 4-chlorobenzamide (7.0 g, 45 mmol) in N,N-dimethylformamide (125 mL) to give 1.41 (23%) as a yellow solid: mp 196-197°C; IR (KBr): 3483, 3317, 1632 and 1525 cm⁻¹; MS: m/z 338 (MH⁺); ¹H NMR (DMSO-d₆): δ 1.20 (s, 3H), 1.39 (s, 3H), 3.79 (m, 1H, simplifies to d, J = 8.8 Hz, with D₂O), 4.98 (m, 1H, simplifies to d, J = 8.8 Hz with D₂O), 5.64 (d, J = 6.0 Hz, 1H, exchanges with D₂O), 6.58 (d, J = 5.3 Hz, 1H), 7.29 (d, J = 5.3 Hz, 1H), 7.56 (d, J = 6.8 Hz, 2H), 7.93 (d, J = 6.8 Hz, 2H) and 8.88 (d, J = 8.3 Hz, 1H, exchanges with D₂O). Anal. Calcd. for C₁₆H₁₆ClNO₃S: C, 56.89; H, 4.77; N, 4.15. Found: C, 56.72; H, 4.68; N, 4.00. EXAMPLE 15 7-(4-Chlorobenzamido)-5,6-dihydro-6-hydroxy-5,5-dimethyl-2-nitro-7H-thieno[3,2-b]pyran The title compound was prepared as described in Example 9 starting with 7-(4-chlorobenzamido)-5,6-dihydro-6-hydroxy-5,5-dimethyl-7H-thieno[3.2-b]pyran (1.23 g, 3.64 mmol) and 90% nitric acid (1.5 mL) in acetic acid (20 mL) to give the product, 0.384 g (28%), as a yellow solid: mp 226-229°C dec; IR (KBr): 3315, 1655, 1535 and 1503 cm⁻¹; MS: m/z 383 (MH⁺); ¹H NMR (DMSO-d₆): δ 1.25 (s, 3H), 1.44 (s, 3H), 3.90 (m, 1H, simplifies to d, J = 8.9 Hz with D₂O), 4.95 (m, 1H, simplifies to d, J = 8.9 Hz, with D₂O), 5.94 (d, J = 6.0 Hz, 1H exchanges with D₂O), 7.60 (d, J = 8.6 Hz, 2H), 7.72 (s, 1H), 7.94 (d, J = 8.6 Hz, 2H) and 9.11 (d, J = 7.6 Hz, 1H, exchanges with D₂O). Anal. Calcd. for C₁₆H₁₅ClN₂O₅S: C, 50.20 H, 3.94; N, 7.32; CL,9.61; S, 8.69. Found: C, 50.34; H, 3.75; N, 7.00 ; Cl, 9.36; S, 8.74 EXAMPLE 16 5,6-Dihydro-6-hydroxy-5,5-dimethyl-7-(4-trifluoromethylbenzamido)-7H-thieno[3,2-b]pyran The title compound was prepared as described in Example 3 starting with 6-bromo-7-hydroxy-5,6-dihydro-5,5-dimethyl-7H-thieno[3,2-b]pyran (4.5 g, 17.1 mmol) and 4-trifluoromethylbenzamide (7.43 g, 39.3 mmol) in N,N-dimethylformamide (75 mL) to give the product, 1.96g (31%), as a colorless solid: mp 162-163°C; IR (KBr): 3396, 1664, 1534 and 1507 cm⁻¹; MS: m/z 372 (MH⁺); ¹H NMR (DMSO-d₆): δ 1.21 (s, 3H), 1.40 (s, 3H), 3.80 (m, 1H, simplifies to d, J = 8.7 Hz, with D₂O), 5.01 (m, 1H, simplifies to d, J = 8.7 Hz, with D₂O), 5.68 (d, J = 6.0 Hz, 1H, exchanges with D₂O), 6.59 (d, J 5.7 Hz, 1H), 7.31 (d, J = 5.7 Hz, 1H), 7.88 (d, J = 8.3 Hz, 2H), 8.11 (d, J = 8.3 Hz, 2H) and 9.05 (d, J = 8.4 Hz, 1H exchanges with D₂O). Anal. Calcd. for C₁₇H₁₆F₃NO₃S: C, 54.98; H, 4.34; N, 3.77. Found: C, 55.01; H, 4.28; N, 3.70. EXAMPLE 17 5,6-Dihydro-6-hydroxy-2-nitro-7-(4-trifluoromethylbenzamido)-7H-thieno[3,2-b]pyran The title compound was prepared as described in Example 9 starting with 5,6-dihydro-5,6-hydroxy-7-(4-trifluoromethylbenzamido)-7H-thieno[3,2-b]pyran (1.5 g, 4.04 mmol) and 90% nitric acid (2.5 mL) in acetic acid (20 mL) to give a yellow solid, 0.165 g (10%): mp 219-220°C; IR (KBr): 3310, 1661, 1538 and 1504 cm⁻¹; MS: m/z 417 (MH⁺); ¹H NMR (DMSO-d₆): δ 1.26 (s, 3H), 1.45 (s, 3H), 3.92 (m, 1H, simplifies to d, J = 8.9 Hz, with D₂O), 4.98 (m, 1H, simplifies to d, J=8.9 Hz, with D₂O), 5.99 (d, 1H, exchanges with D₂O), 7.74 (s, 1H), 7.92 (d, J = 8.5 Hz, 2H), 8.12 (d, J=8.5 Hz, 2H) and 9.30 (d, 1H, exchanges with D₂O). Anal. Calcd. for C₁₇H₁₅F₃N₂O₅S: C, 49.03; H, 3.63; N. 6.73 Found: C, 49.01; H, 3.27; N, 6.60. EXAMPLE 18 5,6-Dihydro-6-hydroxy-5,5-dimethyl-7-pyrrolidin-1-yl-7H-thieno[3,2-b]pyran Sodium hydride (60% in mineral oil, 0.145 g, 3.64 mmol) was added to a solution of 6-bromo-5,6-dihydro-7-hydroxy-7H-thieno[3,2-b]pyran (0.87 g, 3.31 mmol) in N,N-dimethylformamide (30 mL) at 5°C. The resultant solution was stirred at rt for 1.5 h. Pyrrolidine (0.91 mL, 10.9 mmol) was added to the solution and stirred at rt for 17 h. The solution was poured into ice water, and the product was extracted into diethyl ether, washed several times with water and saturated aqueous sodium chloride, and dried over magnesium sulfate. The solvent was evaporated in vacuo and the residue was purified by flash chromatography using 5% methanol in dichloromethane as the eluant to give the product, 0.55 g (66%), as a yellow solid: mp 85-89°C; IR (KBr): 3540, 2970, 2965, 1551 and 1394 cm⁻¹; MS: m/z 254 (MH⁺); ¹H NMR (CDCl₃): δ 1.22 (s, 3H), 1.50 (s, 3H), 1.83 (m, 4H), 2.85 (m, 4H), 3.27 (bs, 1H, exchanges with D₂O), 3.62 (d, J = 9.3 Hz, 1H), 3.90 (d, J = 9.3 Hz, 1H), 6.59 (d, J = 5.4 Hz, 1H) and 7.03 (d, J = 5.4 Hz, 1H). Anal. Calcd. for C₁₃H₁₉NO₂S: C, 61.63; H, 7.56; N, 5.53; S, 12.66. Found: C, 61.38; H, 7.60; N, 5.48; S, 12.58. EXAMPLE 19 6-Hydroxy-5,5-dimethyl-7-(2-oxohexamethyleneimin-1-yl)-7H-thieno[3,2-b]pyran The title compound was prepared as described for Example 3 starting with the bromoalcohol (2.5 g, 9.5 mmol) and caprolactam (2.1 g, 19.0 mmol) to give 1.35 g (48%): mp 153-154°C; IR (KBr): 3200, 1615, 1523 cm⁻¹; MS: m/z 296 (MH⁺); ¹H NMR (CDCl₃): δ 7.13 (d, J=5.4 Hz, 1H), 6.58 (d, J=5.4 Hz, 1H), 5.75 (d, J=9.2 Hz, 1H), 3.69 (m, 1H), 3.36 (d, J= 4.9 Hz, 1H), 3.23 (m, 2H), 2.64 (m, 2H), 1.86 (m, 6H), 1.47 (s, 3H), 1.29 (s, 3H). Anal. Calcd. for C₁₅H₂₁NO₃S: C, 60.99; H, 7.17; N, 4.74; S, 10.85. Found: C, 60.76; H, 6.93; N, 4.76; S. 10.66. EXAMPLE 20 6-Hydroxy-5,5-dimethyl-2-nitro-7-(2-oxohexamethyleneimin-1-yl)thieno[3,2-b]pyran The title compound was prepared as described for Example 5 starting with 6-hydroxy-5,5-dimethyl-7-(2-oxohexamethyleneimin-1-yl)thieno[3,2-b]pyran (0.5 g, 1.7 mmol) and nitric acid (90%, 0.55 mL, 12.3 mmol) in acetic acid (15 mL) to give 410 mg (71%): mp 218-219°C; IR (KBr): 3340, 1627, 1503 cm⁻¹; MS: m/z 341 (MH⁺); ¹H NMR (CDCl₃): δ 7.40 (s, 1H), 5.80 (bd, 1H), 3.73 (d, J=9.5 Hz, 1H), 3.28 (m, 4 H), 2.66 (m, 2 H), 1.87 (m, 4 H), 1.50 (s, 3H), 1.32 (s, 3H). Anal. Calcd. for C₁₅H₂₀N₂O₅S: C, 52.93; H, 5.92; N, 8.23. Found: C, 52.71; H, 5.74; N, 7.84. EXAMPLE 21 6-Acetoxy-5,5-dimethyl-7-(2-oxohexamethyleneimin-1-yl)-thieno-[3,2-b]pyran The title compound was prepared as described for Example 8 starting with 6-hydroxy-5,5-dimethyl-7-(2-oxohexamethyleneiminyl)thieno[3,2-b]pyran (1.5 g, 5.1 mmol) and 70% perchloric acid (10 drops) in acetic anhydride (15 mL) to give 1.5 g (87%): mp 153-154°C; IR (KBr): 1668, 1615, 1563 cm⁻¹; MS: m/z 338 (MH +) ; ¹H NMR (CDCl₃): δ 7.11 (d, J=5.3 Hz, 1H), 6.57 (d, J=5.3 Hz, 1H), 5.99 (d, J=9.0 Hz, 1H), 5.10 (d, J=9.0 Hz, 1H), 3.16 (m, 2H), 2.52 (m, 2H), 2.09 (s, 3H), 1.66 (m, 6H), 1.36 (s, 3H), 1.34 (s, 3H). Anal. Calcd. for C₁₇H₂₃NO₄S: C, 60.51; H, 6.87; N, 4.15. Found: C, 60.71; H, 6.54; N, 3.76. EXAMPLE 22 6-Hydroxy-5,5-dimethyl-7-(2,5-dioxopiperazin-1-yl)-7H-thieno[3,2-b]pyran The title compound was prepared as described for Example 3 starting with the bromoalcohol (2.5 g, 9.5 mmol) and glycine anhydride (2.2 g, 19.0 mmol) to give 0.58 g (36%); mp 132-133°C; IR (KBr): 3210, 1627, 1510 cm⁻¹; MS: 297 (MH⁺). ¹H NMR (CDCl₃): δ 7.13 (d, J=5.4 Hz, 1H), 6.58 (d, J=5.4 Hz, 1H), 5.77 (d, J=9.2 Hz, 1H), 3.54 (m, 1H), 3.46 (d, J= 4.9 Hz, 1H), 3.23 (s, 2H), 2.79 (s, 2H), 1.48 (s, 3H), 1.31 (s, 3H). Anal. Calcd. for C₁₃H₁₆N₂O₄S: C, 52.69; H, 5.44; N, 9.45. Found: C, 52.53; H, 5.23; N, 9.67. EXAMPLE 23 5,6-Dihydro-6-hydroxy-5,5-dimethyl-7-piperidin-1-yl-7H-thieno[3,2-b]pyran The title compound was prepared as described in Example 18 starting with 6-bromo-5,6-dihydro-7-hydroxy-5,5-dimethyl-7H-thieno[3,2-b]pyran (1.5 g, 5.7 mmol) and piperidine (1.7 mL, 17.1 mmol) in N,N-dimethylformamide (25 mL) to give an off white solid, 0.977 (64%): mp 68-70 o C; IR (KBr): 2937, 1549 and 1396 cm⁻¹; MS: m/z 162 (MH⁺); ¹H NMR (CDCl₃): δ 1.20 (s, 3H), 1.50 (s, 3H), 1.52 (m, 2H), 1.61 (m, 4H), 2.65 (m, 2H), 2.78 (m, 2H), 3.20 (bs, 1H, exchanges with D₂O), 3.55 (d, J= 9.3 Hz, 1H), 3.68 (d, J= 9.3 Hz, 1H), 6.58 (d, J= 5.4 Hz, 1H) and 7.04 (d, J= 5.4 Hz, 1H). Anal. calcd. for C₁₄H₂₁NO₂S: C, 62.89; H, 7.92; N, 5.23; S, 11.99. Found: C, 62.86; H, 8.10; N, 5.23; S, 12.12. EXAMPLE 24 6-Benzoyloxy-5,6-dihydro-5,5-dimethyl-7-(2-oxopyrrolidin-1-yl)-7H-thieno[3,2-b]pyran A mixture of 5,6-dihydro-6-hydroxy-5,5-dimethyl-7-(2-oxopyrrolidin-1-yl)-7H-thieno[3,2-b]pyran (1.0 g, 3.74 mmol), benzoic anhydride (10 g) and 70% perchloric acid (10 drops) were heated to 80 o C for 2 h. The mixture was poured into ice water and extracted with dichloromethane and purified by flash chromatography using 1% methanol in dichloromethane as the eluant. The product was further purified by medium pressure chromatography using the same eluant, to give the product, 0.893 g (64%), as a grey solid: mp 130-132 o C; IR (KBr): 2981, 1721, 1695 and 1561 cm⁻¹; MS: m/z 372 (MH⁺); ¹H NMR (CDCl₃): δ 1.43 (s, 3H), 1.49 (s, 3H), 1.96 (m, 2H), 2.23 (m, 1H), 2.33 (m, 1H), 3.31 (m, 1H), 3.47 (m, 1H), 5.44 (d, J= 9.3 Hz, 1H), 5.64 (d, J= 9.3 Hz, 1H), 6.62 (d, J= 5.3 Hz, 1H), 7.15 (d, J= 5.3 Hz, 1H), 7.46 (t, J= 7.4 Hz, 2H), 7.59 (t, J= 7.4 Hz, 1H) and 8.03 (d, J= 7.4 Hz, 2H). Anal. calcd. for C₂₀H₂₁NO₄S: C, 64.67; H, 5.70; N, 3.77; S, 8.63. Found: C, 64.94; H, 5.57; N, 3.59; S, 8.64. EXAMPLE 25 6-Hydroxy-5,5-dimethyl-7-(nicotinamido)-7H-thieno[3,2-b]pyran The title compound was prepared as described for Example 3 starting with 6-bromo-5,6-dihyro-7-hydroxy-5,5-dimethyl-7H-thieno[3,2-b]pyran (4.0 g, 15.2 mmol) and nicotinamide (3.7 g, 30.4 mmol) to give 1.1 g (24%): m.p. 248-49°C; IR (KBr): 3329, 3312,1648, 1594, 1569 cm⁻¹; MS: m/z 305 (MH⁺); ¹H NMR (CDCl₃): δ 9.02 (s, 1H), 8.79 (d, J=5.6 Hz, 1H), 8.14 (d, J=5.6 Hz, 1H), 7.44 (m, 1H), 7.18 (d, J=5.4 Hz, 1H), 6.64 (d, J=5.4 Hz, 1H), 6.55 (d, J=5.6, 1H), 5.20 (m, 1H), 4.46 (brs, 1H), 3.81 (d, J=9.4 Hz, 1H), 1.50 (s, 3H), 1.36 (s, 3H). Anal. Calcd. for C₁₅H₁₆N₂O₃S: C, 59.19; H, 5.30; N, 9.20. Found: C, 58.91; H, 5,10; N, 9.13. EXAMPLE 26 6-Hydroxy-7-(2-imidazolidon-1-yl)-5,5-dimethyl-7H-thieno-[3,2-b]pyran The title compound was prepared as described for Example 3 starting with 6-bromo-5,6-dihydro-7-hydroxy-5,5-dimethyl-7H-thieno[3,2-b]pyran (4.0 g, 15.2 mmol) and 2-imidazolidone (2.9 g, 30.4 mmol) to give 630 mg (15%): m.p. 156-58°C; IR (KBr): 3390, 1698, 1565, 1489 cm⁻¹; MS: m/z 309 (MH⁺); ¹H NMR (CDCl₃): δ 7.13 (d, J=5.4 Hz, 1H), 6.54 (d, J=5.4 Hz, 1H), 5.15 (m, 1H), 4.67 (m, 2H), 3.79 (d, J=9.4 Hz, 1H), 3.24 (m, 2H), 1.48 (s, 3H), 1.31 (s, 3H). Anal. Calcd. for C₁₂H₁₆N₂O₃S: C, 53.71; H, 6.01; N, 10.44. Found: C, 53.78; H, 6.14; N, 10.42. EXAMPLE 27 6-Hydroxy-5,5-dimethyl-7-(isonicotinamido)-7H-thieno[3,2-b]pyran The title compound was prepared as described for Example 3 starting with 6-bromo-5,6-dihydro-7-hydroxy-5,5-dimethyl-7H-thieno[3,2-b]pyran (4.0 g, 15.2 mmol) and isonicotinamide (3.7 g, 30.4 mmol) to give 510 mg (11%): m.p. 223-34°C; IR (KBr): 3324, 3304, 1649, 1569, 1536 cm⁻¹; MS: m/z 305 (MH⁺); ¹H NMR (CDCl₃): δ 8.78 (d, J=5.8 Hz, 2H), 7.63 (d, J=5.8 Hz, 2H), 7.18 (d, J=5.4 Hz, 1H), 6.63 (d, J=5.4 Hz, 1H), 5.19 (m, 1H), 4.28 (brs, 1H), 3.79 (d, J=9.4 Hz, 1H), 1.49 (s, 3H), 1.35 (s, 3H). Anal. calcd. for C₁₅H₁₆N₂O₃S: C, 59.19; H, 5.30; N, 9.20. Found: C, 58.85; H, 5.07; N, 9.05. EXAMPLE 28 5,6-Dihydro-5,5-dimethyl-7-(pyrrolidin-1-yl)-7H-thieno [3,2-b]-pyran A solution of 5,6-dihydro-5,5-dimethylthieno[3,2-b]pyran-7-one (1.0g, 5.5mmol), pyrrolidine (2.3ml, 27.4mmol) sodium cyanoborohydride (0.345g, 5.5 mmol) and 1N aqueous hydrochloric acid (5.5ml, 5.5mmol) in methanol (15ml) was stirred at rt for 1 day. Additional sodium cyanoborohydride (0.345 g, 5.5mmol) was added and the solution was stirred an additional 1 day; additional sodium cyanoborohydride (1.0g, 15,9mmol) was added again and the mixture stirred 5 additional days. The mixture was poured into water (100 ml) and extracted with dichloromethane. The dichloromethane solution was washed with water and dried over sodium sulfate. The solvent was evaporated in vacuo and the residue was purified by medium pressure chromatography using 2% methanol in dichloromethane as the eluant to give the product 0.70g (54%) as a yellow solid; mp 49-50°C; IR(KBr): 2971, 1560 and 1394 cm⁻¹; MS:m/z 238 (MH⁺); ¹H NMR (CDCl₃):δ 1.27(s,3H), 1.45(s3H), 1.80(m,4H), 1.91(m,2H), 2.76(m,4H), 4.09(m,1H), 6.57(d,J=5.4 Hz,1H), and 7.04(d,J=5.4 Hz, 1H). Anal. Calcd. for C₁₃H₁₉NOS:C,65.78; H,8.07; N,5.90. Found: C,65.35; H,8.24; N,5.97 EXAMPLE 29 7-(4-Cyanobenzamido)-5,6-dihydro-6-hydroxy-5,5-dimethyl-7H-thieno[3,2-b]pyran The title compound was prepared as described in Example 3 starting with 6-bromo-7-hydroxy-5,6-dihydro-5,5-dimethyl-7H-thieno[3,2-b] pyran (6.73g, 25.6 mmol), sodium hydride (2.14g, 53.8 mmol), 4-cyanobenzamide (12.0g, 82.1 mmol) and N,N-dimethylformamide (75 ml) to give the product, after recrystallization from dichloromethane and hexanes, 0,82g (10%) as a colorless solid; mp 177-178°C; 1R(KBr): 3420, 1648, 1545 and 1496 cm⁻¹; MS: m/z 329 (MH⁺); ¹H NMR (CDCl₃): δ 1.35(s,3H),1.50(s,3H),3.79 (dd,J=7.8 Hz, J=2.5Hz, 1H, simplifies to d, J-7.8Hz with D₂O), 4.31 (d,J=2.5Hz, 1H, exchanges with D₂O), 5.17 (m, 1H), 6.56(bd, J=6.8Hz, 1H), 6.63(d,J=5.4 Hz, 1H), 7.18(d,J=5.4 Hz, 1H), 7.78 (d,J=8.2 Hz, 2H) and 7.91 (d, J=8.2 Hz,2H). Anal. Calcd for C₁₇H₁₆N₂O₃S: C,62.18; H,4.91;N,8.53 S,9.75. Found: C,62.10; H, 4.74; N, 8.21; S,9.56. EXAMPLE 30 6-Acetoxy-2-acetyl-7-(4-trifluoromethylbenzamido)-5,6-dihydro-5,5-dimethyl-7H-thieno[3,2-b]pyran The title compound was prepared as described in Example 6 starting with 7-(4-trifluoromethylbenzamido)-5,6-dihydro-6-hydroxy-5,5-dimethyl-7H-thieno[3,2-b]pyran (1.5g, 4.04mmol), perchloric acid (70%, 10 drops) and acetic anhydride (20ml) to give the product after crystallization from dichloromethane and hexanes 0.382g (21%) as a colorless solid; mp 225-227°C; IR (KBr):1755, 1668, 1654, 1541 and 1471 cm⁻¹; MS=m/z 456 (MH⁺);¹H NMR (CDCl₃): δ 1.41(s,3H), 1.43 (s,3H), 2.13 (s,3H), 2.47 (s,3H), 5.17 (d,J=9.3 Hz,1H), 5.42(M,1H), 6.77 (bd,J=7.9Hz,1H), 7.14 (s,1H), 7.72 (d,J=8.3 Hz, 2H) and 7.88 (d,J=8.3 Hz,2H). Anal. calcd. for C₂₁ H₂₀ F₃ N0₅S: C,55.42; H,4.43; N,3.08. Found: C,55.06; H, 4.28; N,2.82 EXAMPLE 31 2-Acetyl-7-(4-trifluoromethylbenzamido)-5,6-dihydro-6-hydroxy-5,5-dimethyl-7H-thieno[3,2-b]pyran A mixture of potassium carbonate (92mg, 0.67mmol) and 6-acetoxy-2-acetyl-7-(4-trifluoromethylbenzamido)-5,6-dihydro-5,5-dimethyl-7H-thieno[3,2-b]pyran (0.30g, 0.66mmol) in methanol was stirred at rt for 3h. The mixture was poured into ice water and a white solid crystallized within ten minutes. The solid was collected by filtration, washed with water, air dried and recrystallized from dichloromethane and hexanes to give the product 0.21g (77%) as a colorless solid; mp 227-229°C; IR (KBr): 1652, 1541 and 1414 cm ⁻¹; MS: m/z 414 (MH⁺); ¹H NMR (CDCl₃): δ 1.36 4.37(bs,1H exchanges with D₂O), 5.24 (m,1H), 6.61(bd,1H), 7.17(s,1H), 7.74 (d,J=8.2Hz,2H) and 7.94 (d,J=8.2Hz,2H). Anal. calcd. for c₁₉ H₁₈ F₃ NO₄S: C,55.20; H,4.40; N,3.39. Found: C, 55.21; H,4.21; N, 3.29. EXAMPLE 32 5,6-Dihydro-6-methoxy-5,5-dimethyl-7-(2-oxopyrrolidin-1-yl)-7H-thieno[3,2-b]pyran 5,6-Dihydro-6-hydroxy-5,5-dimethyl-7-(2-oxopyrrolidin-1-yl)-7H-thieno[3,2-b]pyran (1.1g, 4.11mmol) was added to a mixture of sodium hydride (60% in mineral oil, 0.172g, 4.32 mmol) in N,N-dimethylformamide (20ml) at 0°C and stirred for 1.5h. Methyl iodide (0.28ml, 4.52 mmol) was added to the resultant mixture and the mixture stirred at rt for 1h. The mixture was poured into ice water (100 ml) and extracted with dichloromethane. The dichloromethane solution was washed with water (5x) and dried over magnesium sulfate. The solvent was evaporated in vacuo and the residue was crystallized from dichloromethane and hexanes to give the product 0.825g (71%) as a colorless solid; mp 117-118°C; IR(KBr): 2979, 1677, 1572 and 1420 cm⁻¹; MS: m/z 282 (MH⁺); ¹H NMR (CDCl₃): δ 1.27 (s,3H), 1.48(s,3H), 2.05(m,2H), 2.50(m,2H), 3.33(m,2H), 3.41(d,J=8.8Hz, 1H), 3.51(s,3H), 5.33(d,J=8.8Hz, 1H), 6.55(d,J=5.4Hz, 1H) and 7.09 (d,J=5.4Hz, 1H). Anal Calcd. for C₁₄H₁₉ NO₃: C,59.76; H,6.81; N,4.98. Found: C,59.73; H,6.46; N,4.81. EXAMPLE 33 7-Azido-5,6-dihydro-6-hydroxy-5,5-dimethyl-7H-thieno[3,2-b]-pyran . Sodium Hydride (60% in oil, 3.77g, 94.1mmol) was added to a solution of 6-bromo-7-hydroxy-5,6-dihydro-5,5-dimethyl-7H-thieno [3,2-b]pyran (23.6g, 89.7 mmol) in N,N-dimethyl formamide (275 ml) at 0°C. The mixture was stirred at rt for 1.5h and sodium azide (17.0g, 0.269 mol) was added. The resultant mixture was stirred at rt for 3 days, then poured into ice water (1200 ml) and extracted with diethyl ether. The ether solution was washed with water (5x) and dried over magnesium sulfate. The solvent was evaporated in vacuo and the residue was purified by flash chromatography using 15% hexanes in dichloromethane as the eluant to give the product 5.1g (25%) as a tan solid; mp 48-50°C; IR (KBr): 3471, 2104, 1568 and 1402 cm⁻¹; MS:m/z 226(MH⁺); ¹H NMR (CDCl₃): δ 1.31 (s,3H), 1.47 (s,3H), 2.29 (d,J=5.8Hz, 1H, exchanges with D₂O), 3.78(m,1H, simplifies to d, J=7.0 Hz, with D₂O), 4.44(d,J=7.0Hz, 1H), 6.58 (d,J=5.4Hz,1H) and 7.18 (d,J=5.4 Hz,1H). Anal. Calcd. for C₉H₁₁N₃O₂S: C, 47.99; H,4.92; N,18.65. Found: C,48.36; H,4.91; N,18.12 EXAMPLE 34 7-Amino-5,6-dihydro-6-hydroxy-5,5-dimethyl-7H-thieno]3,2-b]-pyran 7-Azido-5,6-dihydro-6-hydroxy-5,5-dimethyl-7H-thieno[3,2-b] pyran (2.0g, 8.88mmol) was added carefully in small portions to a mixture of lithium aluminum hydride (0.67g, 17.8mmol) in diethyl ether (40ml). The resultant mixture was stirred an additional 1h at rt and quenched with successive dropwise addition of water (0.7ml), 15% aqueous sodium hydroxide (0.7ml) and water (2.0ml). The aluminum salts were removed by filtration and the ether solution was dried over magnesium sulfate. The solvent was evaporated in vacuo to give the product 1.64g (93%) as a beige solid; mp 111-116°C; IR(KBr):3110, 2971, 1565 and 1403cm⁻¹; MS:m/z 200 (MH⁺); ¹H NMR (CDCl₃):δ 1.24(s,3H), 1.48(s,3H), 1.85(bs,3H, exchanges with D₂O), 3.38 (d,J=8.6 Hz,1H), 3.70 (d,J=8.6 Hz,1H), 6.55 (d,J=5.4Hz,1H) and 7.07(d,J=5.4Hz,1H). Anal. Calcd. for C₉H₁₃NO₂S: C,54.25; H,6.58; N,7.03; S,1609. Found: C,54.80; H,6.23; N,6.44; S,15.91 EXAMPLE 35 7-(4-Fluorobenzamido)-5,6-dihydro-6-hydroxy-5,5-dimethyl-7H-thieno[3,2-b]pyran A solution of 4-fluorobenzoyl chloride (0.91 ml, 7.72 mmol) in dichloromethane (5 ml) was slowly added to a solution of 7-amino-5,6-dihydro-6-hydroxy-5,5-dimethyl-7H-thieno[3,2-b]pyran (1.4g, 7.03 mmol) and triethylamine (2.9 ml, 21.1 mmol) in dichloromethane (30ml) at 0°C. The resultant mixture was stirred an additional 1h at 0°C, then washed with 1N hydrochloric acid, then with saturated aqueous sodium bicarbonate and dried over magnesium sulfate. The solvent was evaporated in vacuo and the residue was recrystallized from dichloromethane and hexanes to give the product 1.91g (85%) as a colorless solid; mp 162-164°C; IR (KBr): 3365, 1648, 1604, 1535 and 1500 cm⁻¹; MS:m/z 322 (MH⁺); ¹H NMR (CDCl₃:δ 1.35(s,3H), 1.50(s,3H), 3.76(dd, J=2.0Hz, J=7.9Hz, 1H, simplifies to d,J=7.9Hz, with D₂O), 4,72(d, J=2.0Hz, 1H, exchanges with D₂O), 5.14 (m,1H), 6.45(bd,1H), 6.62 (d,J=5.4Hz, 1H), 7.15 (m,3H), and 7.82 (m,2H). Anal Calcd. for C₁₆H₁₆FNO₃S: C, 59.80; H,5.02, N,4.35. Found: C,59.81; H,5.07; N,4.18. EXAMPLE 36 7-Benzamido-5,6-dihydro-6-hydroxy-5,5-dimethyl-7H-thieno-[3,2-b]pyran The title compound was prepared as described in Example 34 starting with benzoyl chloride (0.95ml), triethylamine (3.3ml, 23 mmol) and 7-amino-5,6-dihydro-6-hydroxy-5, 5-dimethyl-7H-thieno[3,2-b]pyran (1.55g, 7.78 mmol) in dichloromethane (35 ml) to give the product 1.07g (45%) as a colorless solid; mp 219-220°C; IR(KBr):3398, 1657, 1526 and 1490 cm⁻¹; MS:m/z 304 (MH⁺); ¹H NMR (DMSO-d₆):δ1.21 (5,3H), 1.39 (5,3H), 3.81 (m,1H, simplifies to d, J=8.8 Hz, with D₂O), 5.00 (m,1H simplifies to d, 5=8.8Hz, with D₂O), 5.61(d,J=6.0Hz, 1H, exchanges with D₂O), 6.58(d,J=5.3Hz,1H), 7.29(d,J=5.3Hz,1H), 7.47(m,3H), 7.92(dd,J=1.3Hz, J=8.2Hz,2H) and 8.79 (d,J=8.3Hz, 1H, exchanges with D₂O). Anal. Calcd. for C₁₆H₁₇NO₃S: C,63.35; H,5.65; N,4.62; S,10.57. Found: C,63.12; H,5.28; N,4.24; S,10.37. In a similar manner, the following compounds were prepared according to the method described in Example 35 where R₁=H, R₅=H, and R₇,R₈=CH₃. Ex. NR₃R₄ R₆ R₂ m.p.(°C) 37 m-ClPhCONH OH H 165-167 38 m-FPhCONH OH H 225(dec) 39 p-MeOPhCONH OH H 218-219 40 p-MePhCONH OH H 226-227 41 m,p-F₂PhCONH OH H 176-181 42 o,p-F₂PhCONH OH H 110-113 43 p-FPhSO₂NH OH H 156-157 44 2-furoylNH OH H 132-134 45 2-thenoylNH OH H 234-236 46 cinnamoylNH OH H 188-189 47 F₅-PhCONH OH H 215-217 48 o-FPhCONH OH H 172-174 49 acetamido OH H 172-174 50 CF₃CONH OH H 160-161 EXAMPLE 51 trans-5,6-Dihydro-6-hydroxy-7-(2-isoindolon-1-yl)-5,5-dimethyl-7H-thieno[3,2-b]pyran A solution of 7-amino-5,6-dihydro-6-hydroxy-5,5-dimethyl-7H-thieno[3,2-b]pyran (1.3 g, 6.5 mmol) in MeOH (5 mL) was slowly added to a solution of 2-carbomethoxybenzaldehyde (5.4 g, 32.7 mmol) in 20 mL MeOH followed by catalytic zinc chloride. The mixture was stirred at rt for 2 h. Sodium cyanoborohydride (0.75 g, 12.2 mmol) was added and the mixture was heated to 40°C overnight. The reaction was poured into ice water and extracted twice with dichloromethane. After concentration in vacuo , the oil was dissolved in 20 mL toluene and heated to 100°C for 5h. The mixture was concentrated and the resulting oil was purified by chromatography (flash, 9:1 dichloromethane-acetone) to give 1.8 g (88%) of the title compound: mp 211-212°C; MS:m/z 316(MH⁺);¹H NMR (CDCl₃):δ 1.21 (s, 3H), 1.57 (s, 3H), 3.99 (d,d, J=3.1Hz, 1H), 4.46 (d, J= 6.0Hz, 1H), 5.56 (d, J=9.2Hz, 1H), 6.60 (d, J=5.4Hz,1H), 7.09 (d, J=5.4 Hz,1H), 7.23-7.64 (m, 4H). Anal Calcd. for C₁₇H₁₇NO₃S: C,64,74; H,5.43; N,4.44. Found: C,64.89; H,5.53; N,4.41. In a similar manner, the following compounds were prepared by the method described in Example 5 where R₁=H, R₅=H, and R₇,R₈=CH₃. EX NR₃R₄ R₆ R₂ m.p.(°C) 52 3-pyridylCONH OH 2-NO₂ 212-213 53 m-ClPhCONH OH 2-NO₂ 109-111 54 p-FPhCONH OH 2-NO₂ 198-202 55 p-MeOPhCONH OH 2-NO₂ 197-198 56 m-FPhCONH OH 2-NO₂ 178-179 57 p-MePhCONH OH 2-NO₂ 107-109 58 m,p-F₂PhCONH OH 2-NO₂ 179-181 59 2-thenoylNH OH 2-NO₂ 196-198 60 2-furoylNH OH 2-NO₂ 195-197 61 o-FPhCONH OH 2-NO₂ 98-100 62 F₅-PhCONH OH 2-NO₂ 150-152 63 cinnamoylNH OH 2-NO₂ 118-120 64 acetamido OH 2-NO₂ 220-224 65 2-oxopyridin-1-yl OH 2-NO₂ 113-114 66 2-isoindolone OH 2-NO₂ 134-136 In a similar manner, the following compounds were prepared by the method described in Examples 6&7 where R₁=H, R₅=H, and R₇,R₈=CH₃. EX NR₃R₄ R₆ R₂ m.p.(°C) 67 3-pyridylCONH OAc 2-Ac 257-258 68 PhCONH OAc 2-Ac 251-253 69 p-FPhCONH OH 2-Ac 191-193 70 PhCONH OH 2-Ac 210-216 71 m-ClPhCONH OH 2-Ac 132-133 72 m,p-F₂PhCONH OH 2-Ac 225-227 73 p-ClPhCONH OAc 2-Ac 210-212 74 p-ClPhCONH OH 2-Ac 212-214 75 p-MeOPhCONH OH 2-Ac 156-157 76 o,p-F₂PhCONH OH 2-Ac 168-170 77 o-FPhCONH OH 2-Ac 210-212 78 m-NO₂PhCONH OH 2-Ac 205-206 79 p-MePhCONH OH 2-Ac 158-160 80 isonicatinamido OAc 2-Ac 138-139 81 pyrrolidinon-1-yl OMe 2-Ac 174-175 82 pyrrolidinon-1-yl OH 2-CF₃CO 111-113 83 acetamido OH 2-Ac 165-168 84 piperidon-1-yl OH 2-Ac 124-126 85 2-isoindolone OH 2-Ac 198-201 In a similar manner, the following compounds were prepared by the method described in Example 4 where R₁=H, R₅=H, and R₇,R₈=CH₃. EX NR₃R₄ R₆ R₂ m.p.(°C) 86 p-FPhCONH OH 2-Br 157-159 87 p-ClPhCONH OH 2-Br 167-169 88 p-FPhSO₂NH OH 2-Br 85-86 89 pyrrolidinon-1-yl OAc 2-Br 130-131 90 piperidon-1-yl OMe 2-Br 171-172 EXAMPLE 91 trans-2-Carbomethoxy-5,6-dihydro-6-hydroxy-5,5-dimethyl-7-(2-oxopiperidin-1-yl)-7H-thieno[3,2-b]pyran A solution of trans-2-bromo-5,6-dihydro-6-hydroxy-5,5-dimethyl-7-(2-oxopiperidin-1-yl)-7H-thieno[3,2-b]pyran (1.35 g, 3.75 mmol), triethylamine (0.87 mL, 6.25 mmol) and bis(triphenylphosphine)-palladium(II) chloride (80 mg, 0.11 mmol) in methanol (120 mL) was heated in a stainless steel Parr pressure reactor pressurized with carbon monoxide (160 psi) at 100 °C for four days. The resultant solution was poured into water and extracted with dichloromethane. The organic phase was dried over magnesium sulfate and the solvent was evaporated in vacuo . The product was purified by flash chromatography using 2% methanol in dichloromethane as the eluant to give the product, 0.83 g (65%) as a colorless solid: mp 104-106°C; IR(KBr): 1718, 1618 and 1565 cm⁻¹; MS: m/z 340(MH⁺); ¹H NMR (CDCl₃):δ 1.29 (s, 3H), 1.49 (s, 3H), 1.43 (m, 4H), 2.53 (m, 2H), 3.14 (m, 1H), 3.23 (m, 1H), 3.52 (d, J=5.4 Hz, 1H, exchanges with D₂O), 3.81 (d,d, J=5.4 Hz, J=9.5 Hz, 1H, simplifies to d, J=9.5 Hz, with D₂O), 3.86 (s, 3H), 5.87 (d, J=9.5 Hz, 1H) and 7.24 (s, 1H). Anal. Calcd. for C₁₆H₂₁NO₅S: C,56.62; H,6.24; N,4.13; S,9.45 Found: C, 56.60; H, 6.36; N, 4.02; S, 9.30. EXAMPLE 92 trans-2-Carboxamido-5,6-dihydro-6-hydroxy-5,5-dimethyl-7-(2-oxopiperidin-1-yl)-7H-thieno[3,2-b]pyran A solution of trans-2-carbomethoxy-5,6-dihydro-6-hydroxy-5,5-dimethyl-7-(2-oxopiperidin-1-yl)-7H-thieno [3,2-b]pyran (1.0 g, 2.94 mmol) in ammonium hydroxide (10 mL) and methanol (10 mL) was stirred at rt for 5 days. The resultant solution was poured into water (60 mL) and the resultant precipitate was collected by filtration, washed with water and air dried. The product was recrystallized from ethanol to give a colorless solid, 0.58 g (61%): mp 287-288°C; IR(KBr): 3200, 1660, 1626, 1615, 1564 and 1480 cm⁻¹; MS: m/z 325 (MH⁺); ¹H NMR(DMSO-d₆): δ 1.17 (s, 3H), 1.39 (s, 3H), 1.58-1.79 (m, 4H), 2.36 (m, 2H), 2.91 (m, 1H), 3.18 (m, 1H), 3.71 (m,1H), 5.60 (bs, 1H), 5.63 (d, J=5.8 Hz, 1H, exchanges with D₂O), 7.23 (s, 1H), 7.39 (bs, 1H) and 7.87 (bs, 1H). Anal. Calcd. for C₁₅H₂₀N₂O₄S: C,55.54; H,6.21; N,8.64; S,9.88 Found: C, 55.19; H, 6.46; N, 8.63; S, 9.64. EXAMPLE 93 trans-2-Carboxy-5,6-dihydro-6-hydroxy-5,5-dimethyl-7-(2-oxopiperidin-1-yl)-7H-thieno[3,2-b]pyran A solution of trans-2-carbomethoxy-5,6-dihydro-6-hydroxy-5,5-dimethyl-7-(2-oxopiperidin-1-yl)-7H-thieno [3.2-b]pyran (0.60 g, 1.76 mmol) and 1 N aqueous sodium hydroxide (1.9 mL) in methanol (15 mL) was stirred at rt for 18 h. An additional 5 drops of 50% sodium hydroxide was added and the solution stirred for 6 additional hours. The solution was poured into water (100 mL) and acidified with conc. hydrochloric acid. A white precipitate was collected by filtration, washed with water and air dried. The product was triturated in diethyl ether to give a colorless solid, 0.505 g (88%); mp 268-270°C; IR(KBr): 1672, 1612, 1582, 1565 and 1490 cm⁻¹; MS: m/z 325(MH⁺); ¹H NMR(DMSO-d₆): δ 1.19 (s, 3H), 1.41 (s, 3H), 1.55-1.84 (m, 4H), 2.37 (m, 2H), 2.96 (m, 1H), 3.22 (m, 1H), 3.38 (bs, 1H, exchanges with D₂O), 3.75 (d, J=8.8 Hz,1H), 5.60 (bs, 1H), 5.69 (bs, 1H, exchanges with D₂O) and 7.17 (s, 1H). Anal. Calcd. for C₁₅H₁₉NO₅S: C,55.37; H,5.89; N,4.30; S,9.85. Found: C, 55.04; H, 5.95; N, 4.08; S, 9.64. EXAMPLE 94 trans-6-Benzyloxy-2-bromo-5,6-dihydro-5,5-dimethyl-7-(2-oxopiperidin-1-yl)-7H-thieno[3,2-b]pyran Sodium hydride (60% in mineral oil, 0.47 g, 11.7 mmol) was added to a solution of trans-2-bromo-5,6-dihydro-6-hydroxy-5,5-dimethyl-7-(2-oxopiperidin-1-yl)-7H-thieno-[3,2-b]pyran (4.0 g, 11.1 mmol) in DMF (50 mL) at 0°C and stirred at rt for 30 min. Benzylbromide (1.45 mL, 12.2 mmol) was added to the resultant solution and stirred at rt for 2 h. The solution was poured into water (200 mL) and extracted into dichloromethane. The organic phase was washed several times with water and dried over magnesium sulfate. The solvent was evaporated in vacuo , and the residue was purified by flash chromatography using 2% methanol in dichloromethane as the eluant. The product was recrystallized from dichloromethane/hexane to give a colorless solid, 3.87 g (77%); mp 146-147°C; IR(KBr): 1634 and 1570 cm⁻¹; MS: m/z 450 (MH⁺); ¹H NMR(CDCl₃):δ 1.32 (s, 3H), 1.50 (s, 3H), 1.53-1.77 (m, 4H), 2.37-2.45 (m, 2H), 2.87 (m, 1H), 3.08 (m, 1H), 3.69 (d, J=8.6 Hz, 1H), 4.60 (d, J=11.8 Hz, 1H), 4.73 (d, J=11.8 Hz, 1H), 5.90 (bs, 1H), 6.54 (s, 1H) and 7.26-7.37 (m, 5H). Anal. Calcd. for C₂₁H₂₄BrNO₃S: C,56.00; H,5.37; N,3.11 Found: C, 56.08; H, 5.44; N, 3.04. EXAMPLE 95 trans-6-Benzyloxy-2-Carbomethoxy-5,6-dihydro-5,5-dimethyl-7-(2-oxopiperidin-1-yl)-7H-thieno[3,2-b]pyran Trans-6-benzyloxy-2-bromo-5,6-dihydro-5,5-dimethyl-7-(2-oxopiperidin-1-yl)-7H-thieno[3,2-b]pyran (1.8 g, 4.0 mmol) was converted to the product using the same procedure described in example 91 to give, after recrystallization from dichloromethane/hexanes a colorless solid, 1.25 g (73%); mp 144-145°C; IR(KBr): 1717, 1646, 1569 and 1472 cm⁻¹; MS: m/z 430 (MH⁺); ¹H NMR(CDCl₃):δ 1.32 (s, 3H), 1.53 (s, 3H), 1.61-1.82 (m, 4H), 2.38-2.55 (m, 2H), 2.90 (m, 1H), 3.08 (m, 1H), 3.80 (bs, 1H), 3.84 (s, 3H), 4.62 (d, J=11.8 Hz, 1H), 4.76 (d, J=11.8 Hz, 1H), 6.02 (bs, 1H), 7.22 (s, 1H) and 7.27-7.38 (m, 5H). Anal. Calcd. for C₂₃H₂₇NO₅S: C,64.31; H,6.34; N,3.26; S,7.46 Found: C, 64.30; H, 6.46; N, 3.21; S, 7.45. EXAMPLE 96 trans-6-Benzyloxy-2-carboxamido-5,6-dihydro-5,5-dimethyl-7-(2-oxopiperidin-1-yl)-7H-thieno[3,2-b]pyran 1/4 hydrate Trans-6-benzyloxy-2-carbomethoxy-5,6-dihydro-5,5-dimethyl-7-(2-oxopiperidin-1-yl)-7H-thieno[3,2-b]pyran (4.0 g, 9.31 mmol) was converted to the product using the same procedure described in example 92 to give, after trituration in diethyl ether, a colorless solid, 2.69 g (70%); mp 228-233°C; IR(KBr): 1667, 1658, 1638, 1613, 1600, 1568 and 1476 cm⁻¹; MS: m/z 415 (MH⁺); ¹H NMR(DMSO-d₆): δ 1.21 (s, 3H), 1.49 (s, 3H), 1.49-1.70 (m, 4H), 2.24-2.35 (m, 2H), 2.93-3.00 (m, 1H), 3.00-3.25 (m, 1H), 3.92 (d, J=9.1 Hz, 1H), 4.63 (d, J=11.9 Hz, 1H), 4.75 (d, J=11.9 Hz, 1H), 5.76 (bs, 1H), 7.26-7.39 (m, 6H), 7.42 (bs, 1H) and 7.90 (bs, 1H). Anal. Calcd. for C₂₂H₂₆N₂O₄S.1/4 H₂O: C, 63.06; H, 6.37; N, 6.68; S, 7.65. Found: C, 62.94; H, 6.75; N, 6.61; S, 7.51. EXAMPLE 97 trans-6-Benzyloxy-2-cyano-5,6-dihydro-5,5-dimethyl-7-(2-oxopiperidin-1-yl)-7H-thieno[3,2-b]pyran Trifluoroacetic anhydride (1.65 mL, 11.7 mmol) in dichloromethane was slowly added to a solution of trans-6-benzyloxy-2-carboxamido-5,6-dihydro-5,5-dimethyl-7-(2-oxopiperidin-1-yl)-7H-thieno[3,2-b]pyran 1/4 hydrate (2.3 g, 5.55 mmol) and pyridine (0.49 mL, 6.10 mmol) in dichloromethane at 0°C and stirred at 0°C for 1 h. The solution was poured into ice water. The organic layer was washed with 1 N hydrochloric acid then 1 N aqueous sodium hydroxide and dried over magnesium sulfate. The solvent was evaporated in vacuo and the residue was purified by flash chromatography using 2% methanol in dichloromethane as the eluant to give a colorless solid which was recrystallized from dichloromethane/hexanes, 1.85 g (84%); mp 174-178°C; IR(KBr): 2211, 1653, 1644, 1556 and 1483 cm⁻¹; MS: m/z 397 (MH⁺); ¹H NMR(CDCl₃):δ 1.32 (s, 3H), 1.53 (s, 3H), 1.60-1.84 (m, 4H), 2.34-2.56 (m, 2H), 2.84-3.10 (m, 2H), 3.82 (bs, 1H), 4.60 (d, J=11.8 Hz, 1H), 4.76 (d, J=11.8 Hz, 1H), 5.92 (bs, 1H), 7.04 (s, 1H) and 7.29-7.38 (m, 5H). trans-2-Cyano-5,6-dihydro-6-hydroxy-5,5-dimethyl-7-(2-oxopiperidin-1-yl)-7H-thieno[3,2-b]pyran Boron tribromide (1.0 M in dichloromethane, 17.6 mL, 17.6 mmol) was slowly added to a solution of trans-6-benzyloxy-2-cyano-5,6-dihydro-5,5-dimethyl-7-(2-oxopiperidin-1-yl)-7H-thieno[3,2-b]pyran (1.4 g, 3.5 mmol) in dichloromethane (40 mL) at 0°C and stirred for 1 h. The solution was poured into ice water. The organic layer was washed with water and dried over magnesium sulfate. The solvent was evaporated in vacuo , and the residue was purified by flash chromatography using 3% methanol in dichloromethane as the eluant. The product was recrystallized from dichloromethane/hexanes to give a colorless solid, 0.997 g (93%); mp 212-214°C; IR(KBr): 2210, 1624, 1558 and 1486 cm⁻¹; MS: m/z 307 (MH⁺); ¹H NMR(CDCl₃):δ 1.29 (s, 3H), 1.50 (s, 3H), 1.77-1.90 (m, 4H), 2.53 (m, 2H), 3.17 (m, 2H), 3.66 (d, J=5.9 Hz, 1H), 3.80 (dd, J=5.9 Hz, J=9.4 Hz, 1H), 5.85 (d, J=9.4 Hz, 1H), 5.92 (bs, 1H) and 7.07 (s, 1H). Anal. Calcd. for C₁₅H₁₈N₂O₃S: C, 58.80; H, 5.92; N, 9.14; S, 10.47. Found: C, 58.86; H, 5.83; N, 9.55; S, 10.30. EXAMPLE 98 trans-5,6-Dihydro-5,5-dimethyl-2-(N,N-dimethylcarboxamido)-7-(2-oxopiperidin-1-yl)-7H-thieno[2,3-b]pyran A solution of trans-2-carbomethoxy-5,6-dihydro-5,5-dimethyl-7-(2-oxopiperidin-1-yl)-7H-thieno[2,3-b]pyran (0.70g, 2.05 mmol) in dimethylamine (40% aqueous solution, 20 mL) and methanol (20 mL) was stirred at rt for 4 days. The resultant solution was poured into water (200 mL) and extracted with 5% isopropanol in dichloromethane. The organic phase was washed with water and dried over magnesium sulfate. The solvent was evaporated in vacuo and the residue was purified by flash chromatography using 3% methanol in dichlormethane as the eluant to give the product as a colorless glass, 0.36 g (50%); IR(KBr); 3362, 2939, 1617, 1569 and 1496 cm⁻¹; MS: m/z 353 (MH⁺); ¹H NMR(CDCl₃):δ 1.30 (s, 3H), 1.49 (s, 3H), 1.80-1.90 (m, 4H), 2.53 (m, 2H), 3.05-3.35 (m, 8H), 3.57 (d, J=4.6 Hz, 1H, exchanges with D₂O), 3.81 (dd, J=4.6 Hz, J=9.3 Hz, 1H), 5.86 (d, J=9.3 Hz, 1H), 6.83 (s, 1H). Anal. calcd. for C₁₇H₂₄N₂O₄S: C, 57.93; H, 6.86; N, 7.95. Found: C, 57.63; H, 6.77; N, 8.40. EXAMPLE 99 N-Methoxy-N-methyl-3,3-dimethylacrylamide 3,3-Dimethylacryloyl chloride (28.2 mL, 0.253 mol) was slowly added to a mixture of N,O-dimethylhydroxylamine hydrochloride (27.2 g, 0.278 mol) and triethylamine (75 mL, 0.519 mol) in dichloromethane (300 mL) at 0 to 30°C and stirred 1 h at 0°C. The resultant mixture was washed with 1 N hydrochloric acid and then with 1 N sodium hydroxide and dried over magnesium sulfate. The solvent was evaporated in vacuo and the residue vacuum distilled (60 to 70°C at 0.2 mm Hg) to give the product, 26.8g (74%) as a colorless oil; IR(neat): 2938 and 1660 cm⁻¹: MS: m/z 144 (MH⁺); ¹H NMR(CDCl₂):δ 1.91 (d, J=1.2 Hz, 3H), 2.14 (d, J=0.9 Hz, 3H), 3.20 (s, 3H), 3.68 (s, 3H), and 6.12 (bs, 1H). 3-t-Butoxy-4-(3-methyl-1-oxo-2-buten-1-yl)thiophene (23) t-Butyllithium (1.7 M in pentanes, 66 mL, 0.112 mol) was added to a solution of 4-bromo-3-t-butoxythiophene (Lawesson, S., Jakobsen, H.J., Tetrahedron, 1965, 21, 3331) (12.49 g, 53.1 mmol) at -75 o C and stirred for 1 h. N-methoxy-N-methyl-3,3-dimethylacrylamide (16.0 g, 0.112 mol) was added to the solution at -75°C and the dry ice acetone bath was removed. The mixture was allowed to stir at ambient temperature overnight. The mixture was washed with 1 N hydrochloric acid and dried over magnesium sulfate. The solvent was evaporated in vacuo and the residue was purified by flash chromatography using 5% diethyl ether in pentanes as the eluant to give 23 as an amber oil, 12.25 g (97%): IR(neat): 2977, 1655, 1612, 1520 and 1470 cm⁻¹: MS: m/z 239 (MH⁺); ¹H NMR (CDCl₃):δ 1.37 (d, 9H), 1.97 (d, J=1.1 Hz, 3H), 2.22 (d, J=1.1 Hz, 3H), 6.56 (d, J=3.6 Hz, 1H), 6.85 (bs, 1H) and 7.86 (d, J=3.6 Hz, 1H). 5,6-Dihydro-5,5-dimethyl-7H-thieno[3,4-b]pyran-7-one (24) A solution of 3-t-butoxy-4-(3-methyl-1-oxo-2-buten-1-yl) thiophene (12.2 g, 51.2 mmol) and p-toluenesulfonic acid (0.5 g) in toluene was heated to reflux for 2 h. The solvent was evaporated in vacuo and the residue was purified by flash chromatography using 25% hexane in dichloromethane as the eluant to give 24 as a waxy tan solid, 5.9 g (63%); mp 42-45 °C; IR(neat): 2977, 1692 and 1554 cm⁻¹: MS: m/z 183 (MH⁺); ¹H NMR(CDCl₃):δ 1.44 (s,6H), 2.62 (s, 2H), 6.43 (d, J=3.3 Hz, 1H) and 8.00 (d, J=3.3 Hz, 1H). Anal. calcd. for C₉H₁₀O₂S: C, 59.32; H, 5.53. Found: C, 59.40; H, 5.58. 3-Bromo-5,6-dihydro-5,5-dimethyl-7H-thieno[3,4-b]pyran-7-one ( 25, R₁=Br) N-Bromosuccinimide (15.0 g, 84.3 mmol) was added to a solution of 5,6-dihydro-5,5-dimethyl-7H-thieno[3,4-b]pyran-7-one (15.0 g, 82.6 mmol) in dichloromethane (300 mL) at 0°C, and the resultant solution was stirred for 2 h at 0°C. The solution was washed with water and dried over magnesium sulfate. The solvent was evaporated in vacuo to give the product as a dark grey solid, 15.1 g (70%), mp 63-72°C; IR(neat): 1694, 1558 and 1438 cm⁻¹: MS: m/z 261 (MH⁺); ¹H NMR(CDCl₃):δ 1.47 (s, 6H), 2.63 (s, 2H),7.99 (s, 1H). Anal. calcd. for C₉H₉BrO₂S: C, 41.40; H, 3.47. Found: C, 41.30; H, 3.46. 3-Bromo-5,6-dihydro-7-hydroxy-5,5-dimethyl-7H-thieno[3,4-b]pyran ( 26,R₁=Br) Sodium borohydride (2.61 g, 69.0 mmol) was added to a solution of 3-bromo-5,6-dihydro-5,5-dimethyl-7H-thieno[3,4-b]pyran-7-one (12.63 g, 48.4 mmol) in ethanol (200 mL) at rt. The mixture was stirred at rt for 3 h and poured into ice water (600 mL) and extracted with diethyl ether. The organic phase was washed with water and dried over magnesium sulfate. The solvent was evaporated in vacuo to give the product as an amber oil, 12.06 g (95%); ¹H NMR(CDCl₃):δ 1.32 (s, 3H), 1.50 (s, 3H), 1.60-2.20 (m, 3H), 4.81 (m, 1H) and 7.26 (s, 1H). 3-Bromo-5,5-dimethyl-5H-thieno[3,4-b]pyran ( 27, R₁=Br) A solution of 3-bromo-5,6-dihydro-7-hydroxy-5,5-dimethyl-7H-thieno[3,4-b]pyran (12.06 g, 45.8 mmol) and p-toluenesulfonic acid (0.26 g, 1.37 mmol) in benzene (300 mL) was heated to reflux for 3 h in an apparatus fitted with a Dean-Stark trap to remove water. The resultant solution was cooled to rt and filtered through a pad of silica gel and the silica gel was washed with dichloromethane; the organic solutions were combined. The solvent was evaporated in vacuo to give the product as a brown oil, 10.23 g (91%);¹H NMR(CDCl₃):δ 1.38 (s,6H), 5.65 (d, J=14 Hz, 1H), 6.37 (d, J=14 Hz, 1H) and 6.87 (s, 1H). trans-3,6-Dibromo-5,6-dihydro-7-hydroxy-5,5-dimethyl-7H-thieno[3,4-b]pyran (28, R₁=Br) N-Bromosuccinimide (7.65 g, 43.0 mmol) was added in portions to a solution of 3-bromo-5,5-dimethyl-5H-thieno[3,4-b]pyran (10.23 g, 41.7 mmol) and water (1.13 mL, 62.6 mmol) in dimethyl sulfoxide (110 mL) at 20 °C. The solution was stirred at rt for 1h and poured into water. The product was extracted into diethyl ether, washed several times with water and dried over magnesium sulfate. The solvent was evaporated in vacuo to give the product as a brown oil, 12.14 g (85%); IR(neat): 1572 and 1457 cm⁻¹: MS: m/z 341 (MH⁺); ¹H NMR(CDCl₃):δ 1.42 (s,3H), 1.66 (s, 3H), 2.55 (bs, 1H, exchanges with D₂O), 4.02 (d, J=9.6 Hz, 1H), 4.86 (d, J=9.6 Hz, 1H) and 7.29 (s, 1H). 3-Bromo-5,6-dihydro-6,7-epoxy-5,5-dimethyl-7H-thieno[3,4-b]pyran (29, R₁=Br) Sodium hydroxide (60% in mineral oil, 0.431 g, 10.8 mmol) was added to a solution of trans-3,6-dibromo-5,6-dihydro-7-hydroxy-5,5-dimethyl-7H-thieno[3,4-b]pyran (3.36 g, 9.81 mmol) in DMF (50mL) and stirred at rt for 2 h. The solution was poured into water (150 mL) and extracted with diethyl ether. The organic phase was washed several times with water and dried over magnesium sulfate. The solvent was evaporated in vacuo to give the product as a brown oil, 2.65 g. The oil was used without further purification. MS: m/z 261 (MH⁺); ¹H NMR (CDCl₃):δ 1.27 (s,3H), 1.62 (s, 3H), 3.39 (d, J=7 Hz, 1H), 3.98 (d, J=7 Hz, 1H) and 7.30 (s, 1H). trans-7-Azido-3-bromo-5,6-dihydro-6-hydroxy-5,5-dimethyl-7H-thieno[3,4-b]pyran (20, R₃R₄N=N₃, R₁=Br) Sodium azide (2.63 g, 40.6 mmol) was added to a mixture of 29 (R₁=Br) (2.65 g, 10.1 mmol) in acetone (40 mL) and water (20 mL) and stirred at rt for 2 h. The resultant solution was poured into water (200 mL) and extracted with diethyl ether. The organic phase was washed with water several times and dried over magnesium sulfate. The solvent was evaporated in vacuo to give an oil which crystallized from hexanes to give the product as a colorless solid, 2.0 g (5%): mp 80-87°C dec.; IR(KBr): 2106, 1576 and 1465 cm⁻¹: MS: m/z 304 (MH⁺); ¹H NMR(CDCl₃):δ 1.28 (s,3H), 1.52 (s, 3H), 2.31 (d, J=4.9 Hz, 1H, exchanges with D₂O), 3.70 (dd, J=4.9 Hz, J=8.7 Hz, 1H, simplifies to d, J=8.7 Hz, with D₂O exchange), 4.35 (dd, J=1.4 Hz, J=8.7 Hz, 1H) and7.23 (d, J=1.4 Hz, 1H). Anal. calcd. for C₉H₁₀BrN₃O₂S: C, 35.54; H, 3.31; N, 13.81. Found: C, 35.77; H, 3.40; N,13.93. trans-7-Amino-5,6-dihydro-6-hydroxy-5,5-dimethyl-7H-thieno[3,4-b]pyran (20, R₃R₄N=NH₂, R₁=H) trans-7-Azido-3-bromo-5,6-dihydro-6-hydroxy-5,5-dimethyl-7H-thieno[3,4-b]pyran (5.32 g, 17.5 mmol) in tetrahydrofuran (60 mL) was slowly added to a suspension of lithium aluminum hydride (1.99 g, 52.5 mmol) in tetrahydrofuran (100 mL). The mixture was heated to reflux for 2 h. The reaction was carefully quenched by adding sequentially water (2 mL), aqueous sodium hydroxide (15%, 2 mL) and water (6 mL). The inorganics were removed by filteration and washed with dichloromethane. The combined organic layers were dried over magnesium sulfate. The solvent was evaporated in vacuo to give the product as a colorless solid, 3.07 g (88%), mp114-116°C ; MS: m/z 200 (MH⁺); ¹H NMR(CDCl₃):δ 1.22 (s,3H), 1.47 (s, 3H), 2.34 (bs, 3H, exchanges with D₂O), 3.36 (d, J=9.8 Hz, 1H), 3.66 (dd, J=1.4 Hz, J=9.8 Hz, 1H), 6.28 (d, J=3.4 Hz, 1H) and 7.10 (dd, J=1.4 Hz, J=3.4 Hz,1H). trans-7-(5-Chloropentamido)-5,6-dihydro-6-hydroxy-5,5-dimethyl-7H-thieno[3,4-b]pyran 5-Chlorovaleryl chloride (2.04 mL, 15.8 mmol) was added dropwise to a solution of 20 (R₃R₄N=NH₂, R₁=H) (3.0 g, 15.1 mmol) and triethylamine (6.3 Ml, 45.2 mmol) in dichloromethane (50 mL) at 0°C. The solution was stirred at 0°C for 1 h. The solution was poured onto a silica gel column and the product purified by flash chromatography using 3% methanol in dichloromethane as the eluant to give the product as an amber oil, 4.83 g (100%); IR(KBr): 3294, 1645, 1561, 1541 and 1453 cm⁻¹; ¹H NMR(CDCl₃):δ 1.27 (s,3H), 1.46 (s, 3H), 1.68-1.96 (m, 4H), 2.25-2.46 (m, 2H), 3.48-3.70 (m, 3H), 4.60 (bs, 1H), 4.97 (m, 1H), 6.20 (bd, 1H), 6.36 (d, J=3 Hz, 1H) and 7.08 (dd, J=1 Hz, J=3 Hz,1H). trans-5,6-Dihydro-6-hydroxy-5,5-dimethyl-7-(2-oxopiperidin-1-yl)-7H-thieno[3,4-b]pyran Sodium hydride (60% in mineral oil, 0.634 g, 15.8 mmol) was added to a solution of trans-7-(5-chloropentamido)-5,6-dihydro-6-hydroxy-5,5-dimethyl-7H-thieno[3,4-b]pyran (4.8 g, 15.1 mmol) in DMF (50 mL) at 0°C and stirred at 0°C for 2 h. The solution was poured into water (250 mL) and extracted with dichloromethane. The organic phase was washed several times with water and poured onto a column of silica gel. The product was purified by flash chromatography using 3% methanol in dichloromethane as the eluant to give a solid which was triturated in diethyl ether to give the product as a colorless solid, 2.92 g (69%): mp 171-172°C; IR(KBr): 3430, 2973, 1613, 1563 and 1488 cm⁻¹: MS: m/z 282 (MH⁺); ¹H NMR(CDCl₃):δ 1.27 (s,3H), 1.48 (s, 3H), 1.78-1.88 (m, 4H), 2.56 (m, 2H), 3.04 (m, 1H), 3.20 (m, 1h), 3.42 (d, J= 4.9 Hz, 1H, exchanges with D₂O), 3.75 (dd, J=4.9 Hz, J=10.1 Hz, 1H), 5.83 (dd, J=1.4 Hz, J=10.1 Hz, 1H), 6.36 (d, J=3.4 Hz, 1H) and 6.86 (dd, J=1.4 Hz, J=3.4 Hz, 1H). Anal. calcd. for C₁₄H₁₉NO₃S: C, 59.76; H, 6.81; N, 4.98; S, 11.40. Found: C, 59.79; H, 6.84; N, 4.87; S, 11.51. EXAMPLE 100 trans-7-Amino-5,6-dihydro-6-hydroxy-5,5-dimethyl-7H-thieno [3,2-b]pyran dibenzoyl-L-tartrate A solution of 7-amino-5,6-dihydro-6-hydroxy-5,5-dimethyl-7H-thieno[3,2-b]pyran (1.73 g, 9.69 mmol) was treated with dibenzoyl-L-tartaric acid (3.3 g, 8.69 mmol) and stirred at rt for 30 min. The mixture was concentrated in vacuo and recrystallized from ethanol to yield 1.8 g (37%) of trans-7-amino-5,6-dihydro-6-hydroxy-5,5-dimethyl-7H-thieno[3,2-b]pyran dibenzoyl-L-tartrate: mp 171-172°C; MS: m/z 200(MH⁺);α D 20° = -84.1°C (MeOH). Anal. Calcd. for C₂₇H₂₇NO₁₀S: C,58.16; H,4.88; N,2.51. Found: C, 57.90; H, 4.72; N, 2.41. EXAMPLE 101 trans-7-Amino-5,6-dihydro-6-hydroxy-5,5-dimethyl-7H-thieno [3,2-b]pyran dibenzoyl-D-tartrate A solution of 7-amino-5,6-dihydro-6-hydroxy-5,5-dimethyl-7H-thieno[3,2-b]pyran (1.73 g, 9.69 mmol) was treated with dibenzoyl-D-tartaric acid (3.3 g, 8.69 mmol) and stirred at rt for 30 min. The mixture was concentrated in vacuo and recrystallized from ethanol to yield 2.1 g (43%) of trans-7-amino-5,6-dihydro-6-hydroxy-5,5-dimethyl-7H-thieno[3,2-b]pyran dibenzoyl-D-tartrate: mp 176-177°C; MS: m/z 200(MH⁺); α D 20° = +75.8°C (MeOH). Anal. Calcd. for C₂₇H₂₇NO₁₀S: C,58.16; H,4.88; N,2.51. Found: C, 58.14; H, 4.94; N, 2.58. 3-Bromo-2-t-butoxythiophene (12) A -78°C solution of 2,3-dibromothiophene (Aldrich, 10.0 g, 41.3 mmol) in 150 mL of diethyl ether was treated with n-butyl lithium (2.5 M, 16.5 mL) over a 20 min period. The mixture was stirred 1h at -78°C. The magnesium bromide (13.0 g, 49.6 mmol) was stirred as a solid in two portions. The mixture was stirred at -78°C for 1h and rt for 2h. t-Butylperbenzoate was added at 0°C and the reaction was allowed to stir at ambient temperature overnight. The mixture was quenched with ice water (50 mL) and 2N HCl (25 mL). The organic layer was separated and washed once with ice cold 1 N NaOH, water and brine. The organic layer was dried over magnesium sulfate and concentrated in vacuo to give 10.5 g (98%) of 12 : MS: m/z 236 (MH⁺); ¹H NMR(CDCl₃):δ 1.36 (s, 9H), 6.61 (d, J= 6.1 Hz, 1H) and 7.23 (d, J= 6.1 Hz, 1H). 2-t-Butoxy-3-(3-methyl-1-oxo-2-buten-1-yl)thiophene (13) A -78°C solution of 12 (9.5 g, 41.5 mmol) in 200 mL of diethyl ether was treated with t-butyl lithium (1.7 M, 27.5 mL) over a 20 min period. The mixture was stirred at -78°C for 1h then treated with N-methoxy-N-methyl-,3,3-dimethylacrylamide (18.0 g, 127.0 mmol). The mixture was allowed to warm to rt overnight. The reaction was poured into ice cold 1N HCl (200 mL) and the organic layer was separated then dried over magnesium sulfate. The filtrate was concentrated in vacuo and the resulting oil was chromatographed (flash, silica gel, dichloromethane) to give 3.5 g (37%) of 13 : MS: m/z 239(MH⁺); ¹H NMR(CDCl₃):δ 1.42 (s, 9H), 1.99 (s, 3H), 2.01 (s, 3H), 6.63 (d, J= 6.1 Hz, 1H), 6.89 (s, 1H) and 7.25 (d, J= 6.1 Hz, 1H). 3,4-Dihydro-3,3-dimethyl-5H-thieno[2,3-b]pyran-5-one ( 14 ) A solution of 13 (2.5 g, 10.5 mmol) in toluene (50 mL) and catalytic p-toluene sulfonic acid was heated to reflux for 3 h. The mixture was concentrated and the resulting oil was chromatographed (flash, silica gel, dichloromethane) to give 1.1 g (58%) of the ketone 14 : MS: m/z 183(MH⁺); ¹H NMR(CDCl₃):δ 1.53 (s, 6H), 2.62 (s, 2H), 6.46 (d, J= 6.1 Hz, 1H) and 7.05 (d, J= 6.1 Hz, 1H). Anal. Calcd. for C₉H₁₀O₂S: C, 59.32; H, 5.53. Found: C, 59.33; H, 5.67. 7-Bromo-3,4-dihydro-3,3-dimethyl-5H-thieno[2,3-b]pyran-5-one ( 15 ) A solution of the ketone 14 (2.0 g, 11.0 mmol) in dichloromethane (20 mL) was treated with N-bromosuccinimide (2.0 g, 11.0 mmol). The mixture was stirred at rt for 3h and quenched with ice cold saturated sodium bicarbonate solution (50 ml). The organic layer was separated, washed with water and dried over magnesium sulfate. The filtrate was concentrated in vacuo to give 2.2 g (77%) of 15 : MS: m/z 263, 261(MH⁺,Br present); ¹H NMR(CDCl₃):δ 1.48 (s, 6H), 2.62 (s, 2H), and 7.02 (s, 1H). Anal. Calcd. for C₉H₉BrO₂S: C, 41.39; H, 3.47. Found: C, 41.53; H, 3.55. 7-Bromo-3,4-dihydro-5-hydroxy-3,3-dimethyl-5H-thieno[2,3-b]pyran ( 16 ) A solution of the ketone 15 (2.2 g, 8.4 mmol) in ethanol (50mL) was treated with sodium borohydride (0.32 g, 8.4 mmol). The mixture was stirred at rt for 5h, quenched with ice water (100 mL) and extracted twice with dichloromethane. The organic layer was dried over magnesium sulfate and concentrated in vacuo to give 2.0 g of the alcohol 16 : MS: m/z: 265, 263 (MH⁺,Br present);¹H NMR(CDCl₃);δ 1.35 (s, 3H), 1.45 (s, 3H), 1.84 (d,d, 1H), 2.10 (d,d, 1H), 4.65 (t, 1H) and 6.91 (s, 1H). 7-Bromo-3,4-dihydro-3,3-dimethyl-5H-thieno[2,3-b]pyran ( 17 ) A solution of the alcohol 16 (2.0 g, 7.6 mmol) in toluene (10 mL) and catalytic p-toluenesulfonic acid was heated under Dean-Stark conditions for 1 h. The mixture was taken up in dichloromethane and washed one with a saturated sodium bicarbonate solution then water. The organic layer was dried over magnesium sulfate and concentrated in vacuo to give 1.7 g (91%) of the olefin 17 ; MS: m/z 247, 245 (MH⁺, Br present); ¹H NMR(CDCl₃):δ 2.01 (s, 6H), 6.23 (d, J= 5.8 Hz, 1H), 6.86 (s, 1H) and 7.26 (d, J= 5.8 Hz, 1H). EXAMPLE 102 Antihypertensive Activity Antihypertensive activity was assessed using a direct measurement of mean arterial blood pressure in spontaneously hypertensive rats (SHR). On the day of the experiment, catheters were implanted into the left carotid artery and the left jugular vein of SHR under light ether anesthesia. The catheters were exteriorized at the nape of the neck and secured with an adhesive wrap. Animals were then placed in stainless steel restraint cages in a quiet room and allowed at least 90 min post-surgical recovery before recordings were collected. Recordings of arterial pressure were obtained using a Statham pressure transducer connected to a Gould 2800 chart recorder. Groups of 4-6 SHR received a single oral dose of drug or vehicle (0.5% methylcellulose) administered by gavage at doses of 0.03 to 20 mg/kg. The percent reduction of mean arterial blood pressure compared to controls is reported. EXAMPLE 103 Rb ⁸⁶ Efflux from Smooth Muscle Rabbit aorta are removed from freshly sacrificed animals. The vessels are cleaned and cut into small circular rings. The rings are placed onto stainless steel wires and immersed in a biological buffer (37°C) bubbled with 95% 0₂/5% CO₂. Rb⁸⁶ (4-5 µCi/mL) is added to 40-50 mL buffer containing all of the aortic rings. This loads each ring with an approximately equal amount of Rb⁸⁶. After 3-4 hours, sets of 2 rings are placed into 4 mL vials of fresh buffer. A background efflux rate is determined over a 30-40 minute period. Test compound is then added to a number of the vials (usually five) as the rings are moved through the 4 mL solutions over a set time period (usually 10 minutes). Finally, the rings are placed into the vials containing no test compound for a period of 10-20 minutes. At the completion of the experiment, the tissues are digested overnight in Prostol before placing into scintillation cocktail to determine the total amount of radioactivity remaining within the tissues. An aliquot is removed from each of the efflux vials and quantitated in a liquid scintillation spectrometer. An efflux rate (or % change from pre-drug rates) is calculated and followed with time in the presence and absence of test compounds. The pharmacological activity of the thienopyran derivatives is summarized below. Blood pressure reduction was measured in the spontaneously hypertensive rats (SHR). The Rb⁸⁶ efflux assay is a measure of potassium ion permeability changes within vascular smooth muscle cells.

Claims: A compound of the formula: and R₁ and R₂ are selected from hydrogen, nitro, cyano, trifluoromethyl, halogen, lower alkyl (C₁₋₄), acyl (C₂₋₄), substituted acyl (C₂₋₄) (wherein the substituent is halogen), benzoyl, substituted benzoyl (wherein the substituent is halogen, alkyl (C₁₋₄), alkoxy (C₁₋₄), acyl (C₂₋₄), nitro, cyano or trifluoromethyl), acylamino (C₂₋₄), alkoxy carbonyl (C₁₋₄), CHO, COOH, CONH₂, CON(R)₂ and NHCOR wherein R is alkyl (C₁₋₄), alkoxy (C₁₋₄), phenyl or substituted phenyl (wherein the substituent is halogen, lower alkyl (C₁₋₄), lower alkoxy (C₁₋₄), nitro, cyano, trifluoromethyl or lower acyl (C₁₋₄)); R₃ and R₄ are selected from hydrogen, acyl (C₂₋₅), alkyl (C₁₋₄), cycloalkyl (C₃₋₆), cycloalkyl carbonyl (C₃₋₆), pyridyl carbonyl, benzoyl, substituted benzoyl (wherein the substituent is halogen, lower alkyl (C₁₋₄), lower alkoxy (C₁₋₄), lower acyl (C₂₋₄), trifluoromethyl, nitro, cyano or RCONH wherein R is alkyl (C₃₋₄)); or R₃R₄N together are a heterocyclic pyrrole, pyrrolidine or piperidine ring, a (C₃₋₉) lactam or a glycine anhydride; R₅ is hydrogen or together with R₆ forms a double bond; R₆ is hydrogen, OH, alkoxy (C₁₋₆), acyloxy (C₂₋₇), benzoyl, or substituted benzoyl (wherein the substituent is halogen, alkyl (C₁₋₄), alkoxy (C₁₋₄), acyl (C₂₋₄), nitro, cyano or trifluoromethyl); and R₇ and R₈ are hydrogen or alkyl (C₁₋₄) or together form a ring having 5-8 carbon atoms, and optical isomers thereof. A compound of claim 1 wherein R₁ and R₂ are hydrogen, halogen, nitro or acyl; R₃ and R₄ are hydrogen, acyl (C₂₋₅), alkyl (C₁₋₄), cycloalkyl (C₃₋₆), cycloalkyl carbonyl (C₃₋₆), benzoyl or substituted benzoyl (wherein the substituent is halogen, lower alkyl (C₁₋₄), lower alkoxy (C₁₋₄), lower acyl (C₂₋₄), trifluoromethyl, nitro, cyano or RCONH wherein R is lower alkyl (C₁₋₄)); R₅ is hydrogen or together with R₆ forms a double bond; R₆ is hydrogen, hydroxy, alkoxy (C₁₋₆), or acyloxy (C₁₋₄) and R₇ and R₈ are hydrogen or alkyl (C₁₋₄). A compound of claim 1 selected from the group consisting of 5,6-Dihydro-6-hydroxy-5,5-dimethyl-7-(4-nitrobenzamido)-7H- thieno[3,2-b]pyran; 6-Acetoxy-2-acetyl-5,6-dihydro-5,5-dimethyl-5-(2-oxopyrrolidin-1-yl)-7H-thieno[3,2-b]pyran; 6-Acetoxy-5,6-dihydro-5,5-dimethyl-7-(2-oxopyrrolidin-1-yl)-7H-thieno[3,2-b] pyran; and 5,6-Dihydro-6-hydroxy-5,5-dimethyl-2-nitro-7-(4-nitrobenzamido)-7H-thieno[3,2-b]pyran. A compound of claim 1 selected from the group consisting of 2-Bromo-5,6-dihydro-6-hydroxy-5, 5-dimethyl-7-(2-oxopiperidin-1-yl)-7H-thieno[3,2-b]pyran; 6-Acetoxy-2-acetyl-5,6-dihydro-5,5-dimethyl-7-(4-nitrobenzamido)-7H-thieno[3,2-b]pyran; 2-Acetyl-5,6-dihydro-6-hydroxy-5,5-dimethyl-7-(4-nitrobenzamido)-7H-thieno[3,2-b]pyran; 7-(4-Chlorobenzamido)-5,6-dihydro-6-hydroxy-5,5-dimethyl-7H-thieno[3,2-b]pyran; 7-(4-Chlorobenzamido)-5,6-dihydro-6-hydroxy-5,5-dimethyl-2-nitro-7H-thieno[3,2-b]pyran; 5,6-Dihydro-6-hydroxy-5,5-dimethyl-7-(4-trifluoromethylbenzamido-7H-thieno[3,2-b]pyran; 5,6-Dihydro-6-hydroxy-2-nitro-7-(4-trifluoromethylbenzamido) -7H-thieno[3,2-b]pyran; 5,6-Dihydro-6-hydroxy-5,5-dimethyl-7-pyrrolidin-1-yl-7H-thieno[3,2-b]pyran; 6-Hydroxy-5,5-dimethyl-7-(2-oxohexamethyleneimin-1-yl)thieno[3,2-b]pyran; and 6-Hydroxy-5,5-dimethyl-2-nitro-7-(2-oxohexamethyleneimin-1-yl)thieno[3,2-b]pyran. A compound of claim 1 selected from the group consisting of 6-Acetoxy-5,5-dimethyl-7-(2-oxohexamethyleneimin-1-yl)thieno[3,2-b]pyran; 6-Hydroxy-5,5-dimethyl-7-(2,5-dioxopiperazin-1-yl)-7H-thieno[3,2-b]pyran; 5,6-Dihydro-6-hydroxy-5,5-dimethyl-7-piperidin-1-yl-7H-thieno[3,2-b]pyran; and 6-Benzoyloxy-5,6-dihydro-5,5-dimethyl-7-(2-oxopyrrolidin-1-yl)-7H-thieno[3,2-b]pyran. A compound of claim 1 which is 5,6-dihydro-6-hydroxy-5, 5-dimethyl-7-(2-oxopyrrolidin-1-yl)-7H-thieno[3,2-b]pyran. A compound of claim 1 which is 2-bromo-5,6-dihydro-6-hydroxy-5,5-dimethyl-7-(2-oxopyrrolidin-1-yl)-7H-thieno[3,2-b]pyran. A compound of claim 1 which is 5,6-dihydro-6-hydroxy-5,5-dimethyl-2-nitro-7-(2-oxopyrrolidin-2-yl)-7H-thieno [3,2-b]pyran. A compound of claim 1 which is 2-acetyl 5,6-dihydro-6-hydroxy-5,5- dimethyl-7-(2-oxopyrrolidin-1-yl)-7H-thieno [3,2-b]pyran. A compound of claim 1 which is 2-acetyl-5,6-dihydro-6-hydroxy-5,5-dimethyl-7-(4-nitrobenzamido)-7H-thieno[3,2-b] pyran. A compound of claim 1 which is 5,6-dihydro-6-hydroxy-5,5-dimethyl-2-nitro-7-(2-oxopiperidin-1-yl)-7H-thieno[3,2-b]pyran. A compound of the formula: X is hydrogen, chloro or bromo; M is keto or hydroxy or M and X together form a double bond; R₁ and R₂ are selected from the group consisting of hydrogen, nitro, cyano, trifluoromethyl, halogen, alkyl (C₁₋₄) acyl (C₂₋₄), substituted acyl (C₂₋₄) (wherein the substituent is halogen), alkoxycarbonyl (C₁₋₄), COOH, CONH₂, CHO, benzoyl, and substituted benzoyl (wherein the substituent is halogen, alkyl (C₁₋₄), alkoxy (C₁₋₄), acyl (C₂₋₄), nitro, cyano or trifluoromethyl); and R₇ and R₈ are hydrogen or alkyl (C₁₋₄) or when taken together form a ring (C₅₋₈). The compound of claim 12 wherein A compound of claim 12 selected from the group consisting of: 5,6-dihydro-5,5-dimethyl-7H-thieno[3,2-b]pyran-7-one, 5,6-dihydro-7-hydroxy-5,5-dimethyl-7H-thieno[3,2-b]pyran, 5,5-dimethyl-5H-thieno[3,2-b]pyran, 3,4-dihydro-3,3-dimethyl-5H-thieno[2,3-b] pyran-5-one, 3,4-dihydro-5-hydroxy-3,3-dimethyl-5H-thieno[2,3-b]pyran, 3,3-dimethyl-3-thieno[2,3-b]pyran, 4,5-dihydro-5,5-dimethyl-7H-thieno[3,4-b]pyran-7-one, 4,5-dihydro-6-hydroxy-5,5-dimethyl-7H-thieno[2,3-b]pyran, and 5,5-dimethyl-7H-thieno[3,4-b]pyran. The process for the preparation of a compound of claim 1 of the formula wherein R₁ and R₂ are hydrogen; R₃ and R₄ are selected from hydrogen, acyl (C₂₋₅), alkyl (C₁₋₄), cycloalkyl (C₃₋₆), cycloalkyl carbonyl (C₃₋₆), pyridyl carbonyl, benzoyl, substituted benzoyl (wherein the substituent is halogen, lower alkyl (C₁₋₄), lower alkoxy (C₁₋₄), lower acyl (C₂₋₄), trifluoromethyl, nitro, cyano or RCONH wherein R is alkyl (C₁₋₄)); or R₃ and R₄ together with nitrogen form a heterocyclic ring, a lactam or a glycine anhydride; R₇ and R₈ are hydrogen or alkyl (C₁₋₄) or together form a ring (C₅₋₈); which comprises reacting a substituted thiophene of the formula wherein R₉ or R₁₀ are selected from alkoxy (C₁₋₄), hydrogen and halogen, with an acryloyl acid derivative to form an unsaturated ketone of the formula Reacting the ketone with a hydrolyzing agent, where R₁₀ is alkoxy, or with a trialkyl tin derivative where R₉ is halo and R₁₀ is alkoxy, to form a ketone of the formula wherein R₁₁ is OH or alkoxy (C₁₋₄), cyclizing the ketone with a cyclizing agent to obtain a keto thienopyran of the formula reacting the keto thienopyran with a reducing agent to form an alcohol of the formula reacting the alcohol with a dehydrating agent to form an olefin of the formula reacting the olefin with a hydro halogenating agent to form a halohydrin of the formula wherein X is bromo or chloro, reacting the halohydrin with base to form an epoxide of the formula reacting the epoxide with an amine or an amide anion. The process for the preparation of a compound of claim 1 of the formula R is hydrogen, acyl, aroyl or COR¹ wherein R¹ is alkyl (C₁₋₄); R₁R₂ are selected from hydrogen, acyl (C₂₋₅), halo, nitro, CHO, COOH and CO₂R₉ wherein R₉ is alkyl (C₁₋₄); and R₃,R₄ and R₇,R₈ are as defined in claim 1; which comprises reacting a substituted thienopyran of the formula (1) wherein R′₁,R′₂ and R′ are hydrogen and R₃,R₄ and R₇,R₈ are as defined above with an acylating agent to form the compounds wherein R is COR¹; or (2) wherein R′₁,R′₂ and R′ are hydrogen and R₃,R₄ and R₇,R₈ are as defined above, with an electrophile selected from halogens and nitric acid to form the compounds wherein R₁,R₂ is halo or nitro and R is hydrogen; or (3) wherein R′₁,R′₂ and R′ are hydrogen, R₃,R₄ and R₇,R₈ are as defined above with an electrophile selected from acyl halides and aroyl halides to form the compounds wherein R₁,R₂ and R are acyl or aroyl; or (4) wherein R′₁ or R′₂ is bromine and R′ is hydrogen, and R₃,R₄ and R₇,R₈ are as defined above, with an organo metallic agent followed by reaction with DMF, CO₂ or an alkylformate to form those compounds wherein R₁,R₂ are CHO, COOH or COOR₉ wherein R₉ is alkyl(C₁₋₄) and R is hydrogen; or (5) wherein R'₁,R'₂ and R' are acyl or aroyl; and R₃,R₄ and R₇,R₈ are as defined above, with a deacylating agent to form those compounds wherein R₁,R₂ are acyl or aroyl and R is hydrogen. The process for the preparation of a compound of claim 1 of the formula R₃R₄ are selected from hydrogen, acyl, alkyl, cycloalkyl, cycloalkyl carbonyl, pyridyl carbonyl, benzoyl or substituted benzoyl (wherein the substituent is halogen, lower alkyl (C₁₋₄), lower alkoxy (C₁₋₄), lower acyl (C₂₋₄), trifluoromethyl, nitro, cyano or RCONH wherein R is alkyl (C₁₋₄)); or R₃R₄N form a heterocyclic ring, a lactam or a glycine anhydride; R₁,R₂ are selected from halocarbonyl, CN, CONH₂, CONHR₉ wherein R₉ is alkyl (C₁₋₄), which comprises (1) reacting a compound of the formula wherein R₁,R₂ = COOH with SOCl₂ to form a Compound of the formula wherein R₁,R₂ are COCl; (2) reacting the product formed with ammonia or an alkyl (C₁₋₄) amine to form the compounds wherein R₁R₂ are CONH₂ or CONHR₉ or (3) reacting the amide with a dehydrating agent to form a compound wherein R₁R₂ = CN. A pharmaceutical Composition in unit dosage form comprising as the active ingredient a compound according to any of claims 1 to 11 in combination with a pharmaceutically acceptable carrier. A compound of claim 1 selected from the group consisting of trans-5,6-Dihydro-6-hydroxy-5,5-dimethyl-7-nicotinamido-2-nitro-7H-thieno-[3,2b]pyran, trans-7-(3-chlorobenzamido)-5,6-dihydro-6-hydroxy-5,5-dimethyl-2-nitro-7H-thieno[3,2-b]pyran, trans-7-(4-fluorobenzamido)-5,6-dihydro-6-hydroxy-5,5-dimethyl-2-nitro-7H-thieno[3,2-b]pyran, trans-7-(3,4-difluorobenzamido)-5,6-dihydro-6-hydroxy-5,5-dimethyl-2-nitro-7H-thieno[3,2b]pyran, trans-5,6-dihydro-6-hydroxy-7-(2-isoindolino)-5,5-dimethyl-2-nitro-7H-thieno[3,2-b] pyran, trans-2-acetyl-7-(4-fluorobenzamido)-5,6-dihydro-6-hydroxy-5,5-dimethyl-7H-thieno[3,2-b]pyran, trans-2-acetyl-7-(4-chlorobenzamido)-5,6-dihydro-6-hydroxy-5,5-dimethyl-7H-thieno[3,2-b]pyran, trans-2-acetyl-7-(2,4-difluorobenzamido)-5,6-dihydro-6-hydroxy-5,5-dimethyl-7H-thieno[3,2-b]pyran, trans-2-acetyl-5,6-dihydro-6-hydrozy-5,5-dimethyl7(3-nitrobenzamido)-7H-thieno[3,2-b]pyran, trans-2-trifluoromethylacetyl-5,6-dihydro-6-hydrozy-5,5-dimethyl-7-(2-oxopyrrolidin-1-yl)-7H-thieno[3,2-b]pyran, trans-2-Acetyl-7-acetamido-5,6-dihydro-6-hydrozy-5,5-dimethyl-7H-thieno[3,2-b]pyran, trans-2-acetyl-5,6-dihydro-6-hydroxy-5,5-dimethy-17-(2-oxopiperidin-1-yl)-7H-thieno[3,2-b]pyran, trans-2-bromo-7-(4-fluorobenzamido)-5,6-dihydro-6-hydrozy-5,5-dimethyl-7N-thieno[3,2-b]pyran, trans-2-bromo-5,6-dihydro-6-methoxy-5,5-dimethyl-7-(2-oxopiperidin-1-yl)-7H-thieno[3,2-b]pyran, and trans-2-cyano-5,6-dihydro-6-hydroxy-5,5-dimethyl-7-(2-oxopiperidin-1-yl)-7H-thieno[3,2-b]pyran. A compound according to any of claims 1 to 14, or 19, for use in therapy. The use of a compound according to any of claims 1 to 14 or 19 in he manufacture of a medicament for treating hypertension in a mammal.

Inventors: FALOTICO ROBERT, MCNALLY JAMES J, PRESS JEFFERY B, SANFILIPPO PAULINE, FALOTICO, ROBERT, MCNALLY, JAMES J., PRESS, JEFFERY B., SANFILIPPO, PAULINE
Applicants: ORTHO PHARMA CORP, ORTHO PHARMACEUTICAL CORPORATION
Application year: 1989
Main classification: C07D495
IPC codes: A61P9, A61K31, A61P3, C07D333, C07D495