BENZOPYRAN DERIVATIVES

Abstract: The invention relates to novel benzopyran derivatives of general formula (I) possessing pharmacological activity, as well as to pharmaceutical compositions containing the compounds of general formula (I) and process for the preparation thereof. In general formula (I) R1 stands for a C1-6alkyloxy, alkenyloxy, alkynyloxy, cycloalkyloxy, aryloxy, aralkyloxy, hydroxy, nitro, cyano, formyl, C1-6acyl or C1-6alkylcyano group or a halo atom, R2 stands for a C1-6alkyloxy, alkenyloxy, alkynyloxy, cycloalkyloxy, aryloxy, aralkyloxy or hydroxyl group, R1 and R2 together stand for alkylenedioxy, and R3 and R4 stand for a C1-6alkyl group.

Description: BENZOPYRAN DERIVATIVES The present invention relates to novel benzopyran derivatives of the general formula possessing pharmacological activity, as well as to pharma¬ ceutical compositions containing the compounds of the gen¬ eral formula (I) . Further, the present invention relates to methods for preparing these compounds and the pharmaceutical compositions containing these compounds as well as novel intermediates. The preparation of certain compounds of the general for¬ mula (I) having hypotensive effect by activating the potass¬ ium canal and pharmaceutically acceptable acid addition salts thereof is disclosed in European patent specifications Nos. 0,076,075, 0,093,535, 0,120,426, 0,120,427, 0,120,428, 0126,311 and 0,126,350. In the general formula (I) Ri stands for a (C 1 _4alkyl)carbonyl, (Cι_4alkoxy)carbonyl, nitro, formyl or cyano group or a halo atom, R 2 stands for a hydrogen atom. - 2 - R 3 stands for a hydrogen atom or a C 1 _ 4 al yl group, R 4 stands for a C 1 _ 4 alkyl group and the lactame ring is in trans position related to the hydroxy grou . The preparation of the compounds as disclosed in the literature is illustrated by reaction scheme No. 1: comprising reacting a suitably substituted phenol of the general formula (II) with 3—chloro—1-propyne of the general formula (III) resulting an arylpropargyl ether of the gen¬ eral formula (IV) , a chromene of the general formula (V) is then formed from the ether by thermic cyclization. There¬ after 3—bromo-4-chromanol of the general formula (VII) may be formed from the chromene of the general formula (V) either in one step by adding hypobromine acid, or in two steps, by hydrolyzing in aqueous acetone 3,4—dibromochromane of the general formula (VI) obtained by adding elementary bromine to chromene of the general formula (V) . 3—Bromo—4- —chromanol is converted into a 3,4—epoxy derivative of the general formula (VIII) in an alkaline medium, compounds of the general formula (I) are then prepared in a specific reaction. The symbols in reaction scheme 1 stand for the following reaction conditions: a: room temperature, a 40% sodium hydroxide solution, benzyl trimethyl ammonium hydroxide and methanol; bJ boiling under reflux in ortho dichlorobenzene; c: N—bromosuccinimide, water and dimethyl sulfoxide; d: bromine and carbon tetrachloride; e: acetone and water; f: sodium hydroxide, water and dioxane; g: 2—pyrrolidone, sodium hydride and dimethyl sulfoxide. If 1-2 does not stand for hydrogen in the process described above, two substances are formed in reaction b as the ring formation may occur at two places. The formed dis¬ advantageous regioisomer of the general formula (Va) has to be separated from the reaction mixture which process is com¬ plicated and decreases the total yield. In European patent specification No. 0,277,611 the prep¬ aration of such benzopyran derivatives of the general for¬ mula (I) is disclosed in which - 4 - R--L stands for an arylsulfonyl or methylsulfonyl group, R 2 stands for a hydrogen atom, a hydroxy or C 1 _ 2 alkoxy group, R 3 is a hydrogen atom or a Cι__4al yl group, R is a c 1 __ alkyl group and the lactame ring is in trans position related to the hydroxy group. In the electrophilic substitution of 4—chromanone of the general formula wherein R stands for C j ^alkoxy, R 3 and R 4 stand for Cι_4- alkyl, a 4-chromanone of the general formula (XVIII) is obtained, latter being reduced to 4-chromanol of the gen- eral formula in a further reaction to obtain a chromene of the general formula (V) in a water eliminating reaction. The derivative of the general formula (I) is obtained from this compound through compounds of the general formula (VII) , then (VIII) . In the formulae Rl stands for an arylsulfonyl or methylsulfonyl group, R 2 stands for a hydrogen atom, hydroxy or C 1 _ 2 alkoxy, R 3 is a hydrogen atom or a Cι_4alkyl group and R4 is a Cι_4alkyl group and the lactame ring is in trans position related to the hydroxy group. No process is known at the same time for the preparation of "the compounds of the general formula (I) , wherein Rl stands for a Cι_galkyloxy, alkenyloxy, alkynyloxy, cyc- loalkyloxy, aryloxy, aralkyloxy, hydroxy, nitro, cyano, formyl, Cι_gacyl or C _6alkylcyano group or a halo atom, R2 stands for a C _galkyloxy, alkenyloxy, alkynyloxy, cyc- loalkyloxy, aryloxy, aralkyloxy or hydroxy group, R and R2 stand together for alkylenedioxy, and R3 and R4 stand together for a Cι_g alkyl group. The above compounds of the general formula are novel. According to literature data (J. Med. Chem. 1990, 33, 492) in compounds of the general formula (I) for reaching hypotensive effect Ri should represent a strong electrone withdrawing substituent and R2 generally a hydrogen atom. We have, however, found that compounds of the general formula (I) according the invention also possess a hypoten- sive effect. These compounds are characterized by being sub¬ stituted together in positions 6 and 7, further, R is not necessarily a strong electrone withdrawing substituent and R2 is not a hydrogen atom. Further, we have found that benzopyrans of the general formula (I) according to our invention also exert their effect by activating the potassium canal. Thus, these com¬ pounds may be useful according to David W. Robertson et al in the following fields of the therapy: a) hypertension; b) asthma; c) diseases of the urinary organs; d) heart fail- ure, g) diseases of the central nervous system; and f) para¬ lysis. The invention provides processes for preparing the new compounds of the general formula (I) through intermediates, the dominant part of which is also novel. According to the invention compounds of the general for¬ mula (I) , wherein Rl stands for a Cι_ 6 alkyloxy, alkenyloxy, alkynyloxy, cyc- loalkyloxy, aryloxy, aralkyloxy, hydroxy, nitro, cyano, formyl, Cι_gacyl or Cι_galkylcyano group or a halo atom, R 2 stands for a Cι__ 6 alkyloxy, cycloalkyoxy, aryloxy, aral¬ kyloxy group, R l and R2 together stand for alkylenedioxy, and R 3 and R 4 stand for a Cι_ 6 alkyl group, may be prepared by reducing a 4-chromanone of the general formula (XVIII) , wherein R stands for a Cι_6alkyloxy, alkenyloxy, alkynyloxy, cyc- loalkyloxy, aryloxy, aralkyloxy, hydroxy, nitro, cyano, formyl, Cι_gacyl or C _ 6 alkylcyano group or a halo atom, R 2 stands for a Cι_galkyloxy, cycloalkyloxy, aryloxy, aral¬ kyloxy group, R l and R 2 together stand for alkylenedioxy, and R 3 and R stand for a C^galkyl group, with metal hydrides, preferably sodium tetrahydroborate, in an amount of 1-5 equivalents, preferably 1.1 equivalents, in a polar or apolar solvent, preferably methanol and/or ben¬ zene, at a temperature of 0 to 100°C, preferably at 25°C, into a 4-chromanol derivative of the general formula (XIX) , boiling said 4—chromanol derivative of the general formula (XIX) in a water immiscible solvent forming with it an azeo- tropic mixture, preferably in benzene, in the presence of a catalytic amount of p-toluene sulfonic acid for the prepara¬ tion of 2H—chromene of the general formula (V) , converting said 2H-chromene of the general formula (V) into a bromo- . _ /HU93/00079 - 7 - hydrine of the general formula (VII) with N-bromosuccinimide in a dipolar aprotic solvent containing water as well, pre¬ ferably in dimethyl sulfoxide, at a temperature of -10 to 50°C, preferably at 15 β C, then reacting said bromohydrine derivative of the general formula (VII) with 2-pyrrolidone in the presence of alkali metal alcoholates, preferably potassium tert-butoxide, at a temperature of 0 to 100°C, preferably at 25°C. Compounds of the general formula (I) , wherein Ri stands for a Cι_ 6 alkyloxy, cycloalkyloxy, aryloxy, aral¬ kyloxy, hydroxy, nitro, cyano, formyl, Cι_ 6 acyl or Cι_ - alkylcyano group or a halo atom, R2 stands for a hydroxy group and R 3 and R4 stand for a Cι_galkyl group, may be prepared hydrogenating compounds of the general for¬ mula (I) , wherein Rl stands for a Cι_ 6 alkyloxy, cycloalkyloxy, aryloxy, aral¬ kyloxy, hydroxy, nitro, cyano, formyl, Cι_ 6 acyl or Cι_g- alkylcyano group or a halo atom, R stands for an aralkyloxy, preferably benzyloxy group and R 3 and R 4 stand for a Cι_ 6 alkyl group, in a polar protic solvent, preferably ethanol, in the pres¬ ence of a catalyst, preferably palladium-on-charcoal cata¬ lyst, at a hydrogen pressure of 1 to 10 bar, preferably 5 bar. Compounds of the general formula (I) , wherein R l stands for a Cι_ 6 alkyloxy, alkenyloxy, alkynyloxy, cyc¬ loalkyloxy, aryloxy, aralkyloxy, hydroxy, nitro, cyano, formyl, Cι_gacyl or Cι_galkylcyano group or a halo atom, R 2 stands for an alkenyloxy or alkynyloxy group and R 3 and R4 stand for a Cι_galkyl group, may be prepared by reacting a compound of the general for¬ mula (I) , wherein Rl stands for a Cι_galkyloxy, alkenyloxy, alkynyloxy, eye- loalkyloxy, aryloxy, aralkyloxy, hydroxy, nitro, cyano, formyl, Cι_ 6 acyl or Cι_galkylcyano group or a halo atom, R 2 stands for a hydroxy group and R 3 and R4 stand for a Cι_ 6 alkyl group, with suitable alkenyl or alkynyl halogenides in a polar aprotic solvent, preferably acetone, in the presence of an acid binding agent, preferably potassium carbonate, and a catalytic amount of potassium iodide. The invention also relates to the novel process by which 4—chromanone of the general formula (XVIII) is prepared. Thus a) if in the formula (X) Ri stands for a nitro group, R 2 is a Cι_ 4 alkyloxy group, R3 and R 4 stand together for a Cι_4dialkyl group, then a compound of the general formula is obtained by nitrating a compound of the general formula (IX) , wherein R is a Cι_ 4 alkylo y group, R 3 and R 4 stand together for a Cι_4alkyl group (reaction scheme No. 2) . 7 - 9 - The nitration is performed with copper(II)nitrate in carboxylic anhydride, preferably acetic anhydride, at a tem¬ perature of 20-100°C, preferably at 40°C. Compounds of the general formula (X) are novel except when R 2 is CH 3 0 (see Panayiotis Anastasis and Philip E. Brown: J. Che . Soc. Per- kin Trans. I., p. 2013-2018, 1982). - 10 - b) If in the formula (XII) Ri stands for a cyano group, R 2 stands for a C _ alkyloxy group, R 3 and R together stand for a C 1 _ 4 alkyl group, then a compound of the general formula (XII) is prepared from a formyl derivative of the general formula (XI) by boiling same in 100% formic acid in the presence of hydroxylamine hydrochloric salt and alkali metal formiate. Said formyl derivative of the general for¬ mula (XI) is obtained by subjecting a compound of the for¬ mula (IX) , wherein R stand for a Cι_ 4 alkyloxy, R 3 and R 4 stand together for a Cι_salkyl, to Vilsmeier formylation (reaction scheme 2) . The preparation is performed by react¬ ing a compound of the general formula (IX) , wherein R 2 stands for a Cι_ 4 alkyloxy group and R 3 and R together stand for a Cι_ 4 alkyl group, in a mixture of phosphorous trichloride oxide and dimethyl formamide at a temperature of 25-100°C, preferably at 80°C, to obtain a derivative of the general formula (XI) , dissolv¬ ing said compound of the general formula (XI) in carboxylic acid and boiling the mixture preferably in formic acid, in the presence of an alkali metal formiate, preferably sodium formiate. The compounds of the general formula (XII) are novel. c) If in the formula (XV) R stands for a C _4 alkyl- cyano group, R stands for a Cι_4 alkyloxy group, R3 and R4 together stand for a Cι_4alkyl group, then 4—chro anone of the general formula (XV) , wherein R 2 stands for a Cι_4al yl- oxy group, R 3 and R4 together stand for a Cι_ 4 alkyl group, is prepared as follows: a compound of the general formula (XI) and acetonitrile are condensed to obtain a compound of the general formula (XIII) . This compound is converted into a compound of the general formula (XIV) by adding water to obtain a compound of the general formula (XV) by catalytic hydrogenation (reaction scheme 2) . The synthesis is carried out by condensing a compound of the general formula (XI) , wherein R 2 stands for a Cι_4alkyloxy group and R 3 and R4 stand together for a Cι_ 4 alkyl group, with acetonitrile in the presence of an alkali metal alcoho- late, preferably potassium tert-butoxide, at a temperature of 0 to 100°C, preferably at 25°C, to obtain compounds of the general formula (XIII) , reacting said compounds of the general formula (XIII) at a temperature of 0 to 100 β C, pre¬ ferably at 25°C, in the presence of a mineral acid, prefer- ably 70% perchloric acid, to obtain a compound of the gen¬ eral formula (XIV) , then hydrogenating said compound of the general formula (XIV) in a polar protic solvent, preferably methanol, in the presence of a catalyst, preferably pallad- iu -on-charcoal catalyst, at a hydrogen pressure of 1 to 10 bar, preferably at 5 bar. Compounds of the general formula (XV) are novel. d) If in general the formula (XVIII) Ri stands for a hydrogen atom, R 2 stands for a hydroxy group, R 3 and R4 together stand for a C 2 _g alkyl group, then 4—chromanone of the general formula (XVIII) is obtained by condensing res- acetophenone of the formula and dialkyl ketone of the general formula in which formulae R3 and R4 together stand for a C _g alkyl group (reaction scheme 3) . The reaction is performed by reacting a resacetophenone of the general formula (XVI) with dialkyl ketone of the gen¬ eral formula (XVII) , wherein R 3 and R stand for C 2 _galkyl, at a temperature of 0 to 100 β C, preferably at 25°C, in the presence of a cyclic secondary amine, preferably pyrroli- dine, in a water-immiscible solvent forming with same an azeotropic mixture, preferably toluene. Compounds of the general formula (XVIII) are novel. The invention also relates to the synthesis of the com¬ pounds of the general formula (I) starting from 4—chromanone of the general formula (XVIII) , by conversing same into chromene of the general formula (V) through of 4—chromano- lone of the general formula (XIX) . The chromene of the gen- eral formula (V) is converted into a 3—bromo-4—chromanol of the general formula (VII) , from which a compound of the gen¬ eral formula (I) is prepared through a 3,4-epoxy derivative of the general formula (VIII) without isolating same (reac¬ tion scheme 4) . The potassium canal activating type compounds of the general formula (I) show hypotensive activity, and can be used in the treatment of hypertension. Accordingly, the pre¬ sent invention also relates to pharmaceutical compositions containing as active ingredient a compound of the general formula (I) in an effective amount together with pharmaceu¬ tically acceptable carriers, as well as to the preparation of said pharmaceutical compositions. The pharmaceutical compositions according to the inven¬ tion are prepared by using usual formulating auxiliaries. The formulation is carried out by methods generally used in the preparation of the known hypotensive agents. Chemical examples The process according to the invention is illustrated by the following non-limiting examples. Example 1 Preparation of (+/-)-6,7-di_aethoxy-3,4-dihydro-2,2-dimetliyl- —trans-4-(2-oxo-l-pyrrolidonyl)-2H-benzo(b)pyran-3-ol 2.20 g (10 mmoles) of 6,7-dimethoxy—2,2—dimethyl—2H- —chromene [prepared according to T. Timar and J. Cs. Jaszbe- renyi in J. Het. Che . 2 , 871 (1988)] are dissolved in 20 ml of dimethyl sulfoxide. The dimethyl sulfoxide contains 0.40 ml of water as well. Then 1.78 g (10 mmoles) of N—bro- mo—succinimide are added in small portions under vigorous stirring and cooling with ice. The reaction mixture is stirred at room temperature for 1 hour and poured onto 200 g of ice. The precipitated white crystalline substance is fil¬ tered off, washed with water and dried. It is pulped with hexane to obtain 2.93 g of 6,7-dimethoxy-trans—3—bromo—3,4- —dihydro—2,2-dimethyl—2H—benzo(b)pyran—4—ol. M.p.: 134-135°C. NMR (CDC1 3 ): 1.41 (3H, 1.57 (3H) , 2.47 (1H, changeable), 4.12 (1H, d, J=10) , 4.86 (1H, m) , 6.35 (1H) , 6,93 (1H) . 2.85 g (9 mmoles) of bromohydrine derivative thus obtained are dissolved in 15 ml of 2—pyrrolidone and 2,01 g (18 mmoles) of potassium tert-butoxide are added thereto portionwise under vigorous stirring and cooling. The reac¬ tion mixture is stirred for further 2 hours at room tempera¬ ture, 100 ml of water are added thereto and the product obtained is extracted with chloroform. The organic phase is washed neutral with water and dried on sodium sulfate to obtain the title product in a yield of 2.08 g. M.p.: 171-172 β C. NMR (CDCI 3 ): 1.25 (3H), 1.48 (3H) , 2.07 (2H, m) , 2.57 (2H, ) , 3.22 (3H, 1 changeable H, broad m) , 3.72 (1H, d, J=10) , 3.77 (3H) , 3.83 (3H) , 5.22 (1H, d, J=10) , 6.38 (1H) , 6.40 (1H). Example 2 Preparation of (+/-)-6-«βthoxy-7-ethoxy-3,4-dihydro-2,2-di- methyl-trans—4-(2-oxo-l-pyrrolidonyl)-2H-benzo(b)pyran—3-ol The process as described in Example 1 is followed. M.p.: 157-158 β C. NMR (CDC1 3 ): 1.26 (3H), 1.45 (3H, t, J=6) , 1.49 (3H) , 2.07 (2H, m) , 2.58 (2H, m) , 3.20 (3H, 1 changeable H, broad m) , 3.72 (1H, d, J=10) , 3.78 (3H) , 4.03 (2H, m) , 5.21 (1H, d, J=10) , 6.38 (2H) . Example 3 Preparation of (+/-)-6-ethoxy-7-methoxy-3,4-dihydro-2,2-di- ethy1-trans—4-(2-oxo-ι-pyrrolidiny1)-2H-benzo(b)pyran-3-ol The process as described in Example 1 is followed. M.p.: 164-165°C. NMR (CDCI3): 1.27 (3H), 1.42 (3H, t, J=6J, 1.50 (3H) , 2.08 (2H, m) , 2.58 (2H, m) , 3.21 (3H, 1 changeable H, m) , 3.74 (1H, d, J=10) , 3.83 (3H) , 3.97 (2H, m) , 5.21 (1H, d, J=10) , 6.40 (1H), 6.42 (1H) . Example 4 Preparation of (+/-)—6-»ethoxy-7-benzyloxy—3,4-dihydro-2,2- — imethyl-trans-4—(2-oxo-l-pyrrolidinyl)-2H-benzo(b)pyran-3- ol The process as described in Example 1 is followed. M.p.: 211-212.5°C. NMR (CDCI 3 ): 1.25 (3H), 1.47 (3H) , 2.07 (2H, m) , 2.57 (2H, m) , 3.18 (3H, 1 changeable H, m) , 3.72 (1H, m) , 3.80 (3H) , 5.07 (2H), 5.21 (1H, d, J=10) , 6.42 (2H) , 7.38 (5H, m) . Example 5 Preparation of (+/-)-6-»etho_-y-7-hidro_-ry-3,4-dihydro-2,2-di- methyl-trans— —(2-oxo-l-pyrrolidinyl)-2H-benzo(b)pyran-3-ol 0.39 g (1 mmole) of the 6-methoxy-7-benzyloxy derivative prepared as described in Example 4 are dissolved in 20 ml of methanol. 0.1 g of 10% palladium on charcoal catalyst is added thereto and the reaction mixture is hydrogenated at a hydrogen pressure of 5.0 bar under stirring. The reaction time is 6 hours. The catalyst is filtered off and the solu¬ tion is evaporated. The oily product is dissolved in 50 ml of chloroform and washed with water. The phases are separ¬ ated, dried over sodium sulfate and evaporated to obtain the title product in a yield of 0.25 g. M.p.: 260°C (decomposition). NMR (CDC1 3 ): 1.25 (3H) , 1.47 (3H) , 2.07 (2H, ) , 2.58 (2H, m) , 3.23 (3H, 1 changeable H, m) , 3.74 (1H, ) , 3.81 (3H) , 5.21 (1H, d, J=10) , 5.65 (1H, changeable), 6.36 (1H) , 6.43 (1H). Example 6 Preparation of (+/-)-6,7-dibenzyloxy-3,4-dihydro-2,2-di- methyl-trans-4-(2-oxo-l-pyrrolidinyl)-2H-benzo(b)pyran-3-ol The process as described in Example 1 is followed. M.p.: 162-163°C. NMR (CDC1 3 ): 1.23 (3H) , 1.46 (3H) , 1.67 (1H, m) , 1.91 (1H, m) , 2.42 (2H, m) , 2.71 (1H, m) , 3.02 (2H, m) , 3.63 (1H, m) , 5.12 (5H, m) , 6.32 (1H) , 6.46 (1H) , 7.35 (10H) . Example 7 Preparation of (+/-)-6,7-dihydroxy-3,4-dibydro-2,2-di_aethyl- —trans-4—(2-oxo-l-pyrrolidinyl)-2H-benzo(b)pyran-3-ol A 6,7—dibenzyloxy derivative prepared as described in Example 6 is hydrogenated as described in Example 5. The reaction time is 10 hours. M.p.: decomposition. NMR (CDC1 3 ): 1.26 (3H) , 1.48 (3H) , 2.07 (2H, m) , 2.57 (2H, m) , 3.23 (3H, 1 changeable H, m) , 3.75 (1H, m) , 5.22 (1H, d, J=10) , 5.70 (2H, broad, changeable), 6.33 (1H) , 6.46 (1H) . Example 8 Preparation of (+/-)-6,7-πιethylenedioxy-3,4— ihydro-2,2-di- ethyl-trans-4-(2-oxo-l-pyrrolidinyl)-2H-benzo(b)pyran-3-ol The process as described in Example 1 is followed. M.p.: 161-162 β C. NMR (CDCI 3 ): 1.25 (3H), 1.48 (3H) , 2.08 (2H, m) , 2.60 (2H, ) , 3.22 (3H, 1 changeable H, m) , 3.72 (IH, d, J=10) , 5.15 (IH, d, J=10) , 5.90 (2H, m) , 6,35 (2H) . Example 9 Preparation of (+/-)-6-bro_αo-7-__.ethoxy-3,4-dihydro-2,2-di- ethyl-trans-4-(2-oxo-l-pyrrolidinyl)-2H-benzo(b)pyran-3-ol 1.9 g (10 mmoles) of 7-methoxy-2,2-dimethyl-2H-chromene are dissolved in 20 ml of dimethyl—sulfoxide containing 0.40 ml of water, too. 3.56 g (20 mmoles) of N—bromo—succinimide are added thereto portionwise under vigorous stirring and external cooling with icy water. The reaction mixture is stirred at room temperature in room temperature then poured onto 200 g of crushed ice. The precipitated white crystal- line substance is filtered off, washed with water and dried. The product is pulped with hexane to obtain 3.09 g of 6—bro¬ mo—7-methoxy-trans—3—bromo-3,4—dihydro-2,2-dimethyl—2H—ben- zo(b)pyran—4—ol. M.p.: 58-59 β C. NMR (CDCI 3 ): 1.42 (3H) , 1.61 (3H) , 2.70 (IH, changeable), 3.68 (3H) , 4.08 (IH, d, J=10) , 4.85 (IH, d, J=10) , 6.35 (IH), 7.62 (IH) . 2.92 g (8 mmoles) of the bromohydrine derivative thus obtained are dissolved in 20 ml of 2-pyrrolidone, then 1.78 g (16 mmoles) of potassium tert-butoxide are added thereto under vigorous stirring and external cooling with icy water. The reaction mixture is stirred at room temperature for 4 hours, 100 ml of water are added thereto and the product is extracted with chloroform. The phase containing the chloro- form is washed neutral with water, dried over sodium sulfate and evaporated to obtain the title product in a yield of 2.39 g. M.p.: 165-166°C. NMR (CDCI 3 ): 1.27 (3H), 1.52 (3H) , 2.13 (2H, m) , 2.70 (2H, ) , 3.25 (3H, 1 changeable H, m) , 3.76 (IH, d, J=10) , 3.86 (3H), 5.22 (IH, d, J=10) , 6.41 (IH) , 7.05 (IH) . Example 10 Preparation of (+/-)-6-chloro-7-methoxy-3,4-dihydro-2,2-di- methyl-trans-4-(2-oxo-l-pyrrolidinyl)-2H-benzo(b)pyran-3-ol Starting from 6-chloro-7—alkyloxy-2,2-dimethyl-2H-chro- mene [prepared according to P. Sebδk et al in Acta Chim. Hung 126(4), 471 (1989)] one proceeds as described in Example 1. M.p.: 196-197.5°C. NMR (CDC1 3 ): 1.27 (3H) , 1.51 (3H) , 2.10 (2H, m) , 2.58 (2H, m) , 3.16 (3H, 1 changeable H, m) , 3.72 (IH, ) , 3.85 (3H) , 5.21 (IH, d, J=10) , 6.42 (IH) , 6.88 (IH) . Example 11 Preparation of (+/-)-6-nitro-7-methoxy-3,4-dihydro-2,2-di- methyl-trans-4-(2-oxo-l—pyrrolidinyl)-2H-benzo(b)pyran-3-ol 2.06 g (10 mmoles) of 7-methoxy-2,2-dimethyl-4-chroma- none are dissolved in 12.5 ml of acetic anhydride. 3.02 g (12.5 mmoles) of Cu(Nθ 3 ) 2 *3H2θ are added thereto in small portions under vigorous stirring while the temperature rises to 70°C. Then the mixture is stirred at 40°C for 1.5 hours and poured onto 200 g of crushed ice. 1.88 g of yellowish crystalline 6—nitro—7— ethoxy—2,2-dimethyl-4-chromanone are obtained, which is recrystallized in ethanol. M.p.: 259-261°C. NMR (CDC1 3 ) : 1.50 (6H), 2.72 (2H) , 3.97 (3H) , 6.52 (IH) , 8.51 (IH) . 1.75 g (7 mmoles) of 6-nitro-7-methoxy-2,2-dimethyl-4- —chromanone are dissolved in 30 ml of methanol. 0.53 g (14 mmoles) of sodium boron hydride are added under vigorous stirring, the mixture is stirred at room temperature for 1 hour, the methanol is distilled off in vacuo, 100 ml of di- chloromethane are added thereto and it is washed neutral with water. The organic phase is dried on sodium sulfate. dried and evaporated. 50 ml of benzene and 0.1 g of para- toluol sulfonic acid are added and boiled under reflux for 1 hour. The cooled solution is washed with water, dried over sodium sulfate and the benzene is distilled off in vacuo to obtain 1.48 g of 6-nitro-7-methoxy-2,2-dimethyl-2H-chromane. M.p.: 79-80°C. NMR (CDC1 3 ): 1.46 (6H), 3.92 (3H) , 5.60 (IH, d, J=10) , 6.27 (IH, d, J=10) , 6.43 (IH), 7.70 (IH) . 1.41 g (6 mmoles) of 6—nitro-7— ethoxy-2,2—dimethyl—2H- —chromene are dissolved in 15 ml of dimethyl sulfoxide con¬ taining 0.3 ml of water. 1.06 g (6 mmoles) of N-bromosuccin¬ imide are added under vigorous stirring and external cooling with ice. The reaction mixture is stirred at room tempera¬ ture for 1.5 hours and poured onto 200 g of crushed ice. The precipitated white crystalline substance is filtered off, washed with water and dried to obtain 1.85 g of 6-nitro—7- —methoxy—trans—3-bromo-3,4-dihydro-2,2-dimethyl-2H-benzo(b)- pyran—4-ol. M.p.: 143-145°C. NMR (CDCI3): 1.45 (3H) , 1.63 (3H) , 2.72 (IH, broad, change¬ able), 3.90 (3H), 4.08 (IH, d, J=9.5), 4.87 (IH, d, J=9.5), 6.44 (IH) , 8.19 (IH) . 1.82 g (5.5 mmoles) of the bromohydride derivative thus obtained are dissolved in 15 ml of 2-pyrrolidone, then 1.23 g (11 mmoles) of 1.23 g of potassium tert-butoxide are added portionwise under vigorous stirring and external cooling with icy water. The reaction mixture is stirred at room tem¬ perature for 2 hours, 100 ml of water are added the product is extracted with chloroform. The organic phase is washed neutral with water, washed, dried over sodium hydride and evaporated to obtain the title product in a yield of 1.50 g. M.p.: 255-257°C. NMR (CDCI 3 ): 1.20 (3H) , 1.44 (3H) , 1.93 (2H, m) , 2.37 (2H, m), 2.92 (2H, m), 3.67 (IH, dd, Jι)=10, J 2 =6) , 3,83 (3H) , 4.90 (IH, d, Jι=10), 5.73 (IH, d, J 2 =6, changeable), 6.69 (IH), 7.43 (IH). Example 12 Preparation of (+/-)-6-nitro-7—ethoxy—3,4-dihydro-2,2-di- methyl— rans-4-(2-oxo-l-pyrrolidinyl)-2H-benzo(b)pyran-3-ol The process as described in Example 11 is followed. M.p.: 225.5-226.5°C. NMR (CDC1 3 ): 1.31 (3H) , 1.47 (3H, t, J=6) , 1.53 (3H) , 2.12 (2H, m) , 2.70 (2H, m) , 3.10 (IH, m) , 3.33 (IH, m) , 3.73 (IH, ), 3,93 (IH, m, changeable), 4.11 (2H, m) , 5.22 (IH, d, J=10) , 6.45 (IH), 7.58 (IH) . Example 13 Preparation of (+/-)-6-nitro-7-n-propyloxy-3,4-dihydro-2,2- -diπιethyl-trans-4-(2-oxo-l-pyrroli inyl)-2H-benzo(b)pyran-3- -ol The process as described in Example 11 is followed. M.p.: 207.5-209.5°C. NMR (CDCI3): 1.07 (3H, t, J=6) , 1.30 (3H) , 1.53 (3H) , 1.86 (2H, m) , 2,11 (2H, m) , 2.57 (2H, m) , 3.22 (3H, 1 changeable H, m) , 3.74 (IH, ) , 4.00 (2H, m) , 5,25 (IH, d, J=10) , 6.45 (IH), 7.59 (IH) . Example 14 Preparation of (+/-)-6-nitro-7-isopropoxy-3,4-dihydro-2,2- -dimethyl-trans-4-(2-oxo-l-pyrrolidinyl)-2H-benzo(b)pyran-3- -ol The process as described in Example 11 is followed. M.p.: 221.5-222.5°C. NMR (CDCI 3 ): 1.31 (3H), 1.38 (6H) , 1.52 (3H) , 2.07 (2H, m) , 2.56 (2H, m) , 3.12 (IH, m) , 3.35 (IH, m) , 3.72 (IH, dd, J 2 =10) , 4.09 (IH, d, changeable, , IH, m) , 5.21 (IH, d, J 2 =10) , 6.45 (IH), 7.53 (IH) . Example 15 Preparation of (+/-)-6-cyano-7—methoxy—3, -dihydro-2,2-di¬ methy1— rans— —(2-oxo—1-pyrrolidinyl)—2H—benzo(b)pyran—3-ol 4.50 g (17.8 mmoles) of 6—formyl—4—chloro—7—methoxy—2,2- —dimethyl—2H—chromene [prepared according to the method of P. Brown et al, J. Chem. Soc. Perkin Trans. (I) , 1127 (1985) and T. Eszenyi and T. Timar, Synth. Comm. , () (1990) 3219] are suspended in 40 ml of 100% of formic acid, 1.50 g (21 mmoles) of hydroxy1 ammonium chloride and 2.50 g (24 mmoles) of sodium carbonate or an equivalent amount of sodium formi¬ ate are added. The reaction mixture is boiled under reflux for 3 hours, then poured onto 200 g of crushed ice. The separated beige precipitate is filtered off, washed with water and dried to obtain the title product in a yield of 3.89 g. M.p.: 116-118°C. NMR (CDC1 3 ): 1.50 (6H), 2.72 (2H) , 3.95 (3H) , 6.45 (IH) , 8.15 (IH). 4.0 g (17.3 mmoles) of 6--cyano—7-methoxy—2,2-dimethy1-4- —chromanone and 0.72 g (19 mmoles) of sodium boron hydride are suspended in 40 ml of benzene, then 10 ml of methanol are added dropwise while heated to reflux temperature. After a reaction time of half an hour the reaction mixture is cooled to 5-10°C, the precipitate is filtered off and the benzene solution is evaporated. The evaporation residue is again dissolved in 20 ml of benzene, 0.4 g of para-toluene sulfonic acid are weighed in and the reaction mixture is boiled under reflux. Then it is cooled down, washed with water, dried on sodium sulfate and evaporated to obtain 3.12 g of a white crystalline substance. M.p.: 92-94°C. NMR (CDCI 3 ): 1.45 (6H), 3.90 (3H) , 5.57 (IH, d, J=10) , 6.25 (IH, d, J=10) , 6.40 (IH), 7.15 (IH) . 2.15 g (10 mmoles) of 6-cyano—7-methoxy-2,2-dimethy1—2H- —chromene are dissolved in 20 ml of dimethyl sulfoxide con¬ taining also 0.4 ml of water. Then 1.78 g (10 mmoles) of N- bromo-succinimide are added under external cooling with water and the reaction mixture is let to react for 2 hours at room temperature. Then it is poured onto 200 g of ice, the separated white precipitate is filtered, washed with water and dried to obtain 2.55 g of 6—cyano—7—methoxy- —3,4—dihydro-2,2-dimethy1—trans—3-bromo-4—hydroxy—2H—benzo- (b)pyran. M.p.: 144-146°C. NMR (CDC1 3 ):1.45 (3H) , 1.65 (3H) , 2.85 (IH, changeable), 3.88 (3H) , 4.08 (IH, d, J=10) , 4.88 (IH, d, J=10) , 6.38 (IH), 7.73 (IH). 2.55 g (8.2 mmoles) of the bromohydrine derivative thus- obtained are dissolved in 8 ml of 2-pyrrolidone, then 1.99 g (17.2 mmoles) of 97% potassium tert-butoxide are added under external cooling with water. The reaction mixture is stirred for 4 hours at room temperature, poured onto 100 g of crushed ice, the white precipitate is filtered off, washed with icy water, dried and crystallized from butanol to obtain the title product in an amount of 1.81 g. M.p.: 239-241°C. NMR (CDC1 3 ): 1.30 (3H) , 1.55 (3H) , 2.13 (2H, m) , 2.58 (2H, t) , 3.09-3.35 (2H, m) , 3.73 (IH, d, J=10) , 3.88 (3H) , 5.20 (IH, d, J=10) , 6.40 (IH) , 7.13 (IH) . Example 16 Preparation of (+/-)-6-cyano-7-ethoxy-3,4-dihydro-2,2-di¬ methy1—trans-4-(2-oxo-l-pyrrolidinyl)-2H-benzo(b)pyran-3-ol The process as described in Example 15 is followed. M.p.: 227-229°C. NMR (CDC1 3 ): 1.30 (3H), 1.48 (3H, t) , 1.53 (3H) , 2.13 (2H, m) , 2.63 (2H, t) , 3.08 (IH, m) , 3.40 (IH, m) , 3.73 (IH, d, J=10) , 4.10 (2H, m) , 5.18 (IH, d, J=10) , 6.38 (IH) , 7.10 (IH). Example 17 Preparation of (+/-)-6-cyano-7-propyloxy-3,4-dihydro-2,2-di- methyl-trans-4-(2-oxo-l-pyrrolidinyl)-2H-benzo(b)pyran-3-ol The process as described in Example 15 is followed. M.p.: 211-213°C. NMR (CDC1 3 ): 1.05 (3H, t) , 1.30 (3H) , 1.55 (3H) , 1.85 (2H, m) , 2.13 (2H, m) , 2.58 (2H, t) , 3.0 (IH, m) , 3,35 (IH, m) , 3.70 (IH, d, J=10) , 3.95 (2H) , m) , 5,20 (IH, d, J=10) , 6.38 (IH), 7.10 (IH) . Example 18 Preparation of (+/-)—6-cyano-7—(l-methylethoxy)-3,4-dihydro- —2 ,2-dimethyl-trans-4-(2-oxo-l-pyrrolidinyl)-2H-benzo(b)- pyran—3-ol The process as described in Example 15 is followed. M.p.: 213-215 β C. NMR (CDC1 3 ): 1.30 (3H) , 1.40 (6H, t) , 1.55 (3H) , 2.13 (2H, m) , 2.58 (2H, t) , 3.10 (IH, m) , 3.35 (IH, m) , 3.70 (IH, d, J=10) , 4.55 (IH, m) , 5.20 (IH, d, J=10) , 6.38 (IH) , 6.38 ( H), 7.10 (IH). Example 19 Preparation of (+/-)-6-cyano-7-{l-methylpropyloxy)-3,4-di- hydro-2,2-dimethyl-trans-4-(2-oxo-l-pyrrolidinyl)-2H-benzo- (b)pyran-3-ol The process as described in Example 15 is followed. M.p.: 199-210°C. NMR (CDCI 3 ): 1.02 (3H, t) , 1.32 (6H, m) , 1.55 (3H) , 1.72 (2H, m) , 2.12 (2H, m) , 2.57 (2H, t) , 3.10 (IH, m) , 3,32 (IH, m) , 3.72 (2H, m) , 4.30 (IH, m) , 5.17 (IH, d, J=10) , 6.35 (IH), 7.10 (IH). Example 20 Preparation of (+/-)—7-benzyloxy-6-cyano-3,4-dihydro-2,2-di¬ methyl-trans-4-(2-oxo-l-pyrrolidinyl)-2H-benzo(b) yran-3-ol The process as described in Example 15 is followed. M.p. : 233-235°C. NMR (CDCI3): 1.28 (3H, s) , 1.52 (3H, s) , 2.12 (2H, ») , 2.57 (2H, t) , 3.07 (IH, m) , 3.30 (2H, m) , 3.70 (IH, m) , 5.17 (3H, m) , 6.45 (IH, S) , 7.15 (IH, s) . Example 21 Preparation of (+/-)-7-hydroxy-6-cyano—3, -dihydro-2,2-di- methyl-trans—4—(2—oxo—l-pyrrolidinyl)-2H-benzo(b)pyran-3-ol Starting from a 6-cyano—7-bezyloxy derivative prepared according to Example 20, the process as described in Example 5 is followed. M.p.: 280°C (decomposition). NMR (DMSO-dg): 1.16 (3H, S) , 1.40 (3H, s) , 1.97 (2H, m) , 2.38 (2H, m) , 2.92 (IH, m) , 3.30 (IH, m) , 3.62 (IH, d, J=10) , 4.85 (lH,d, J=10) , 5.64 (IH, changeable H) , 6.37 (IH, s) , 7.06 (IH, s) , 11.00 (IH, changeable H) . Example 22 Preparation of (+/-)-7-allyloxy-6-cyano-3,4-dihydro-2,2-di¬ methyl-trans-4-(2—oxo-l-pyrrolidinyl)-2H-benzo(b)pyran-3-ol 0.30 g (1 m ole) of a compound according to Example 21 is reacted with 0.34 g (1.2 mmoles) of allylbromide in 15 ml of acetone for 4.5 hours at reflux temperature in the pres¬ ence of 0.20 g of potassium carbonate and a catalytic amount of potassium iodie. The reaction mixture is cooled back, filtered off and evaporated and the rough product obtained is recrystallized from ethyl acetate. M.p.: 204-206 β C NMR (CDCI 3 ): 1.28 (3H, s) , 1,52 (3H, s) , 2.10 (2H, m) , 2.54 (2H, t) , 3.05 (IH, m) , 3.32 (IH, m) , 3.72 (2H, m, 1 change¬ able H) , 4.59 (2H, d, J=6) , 5.18 (IH, d, J=10) , 5.25-5.55 (2H, m) , 5.90-6.15 (IH, m) , 6.39 (IH, s) , 7.12 (IH, S) . Example 23 Preparation of (+/-)-6-formyl-7-methoxy-3,4-dihydro-2,2-di- methyl-trans-4-(2-oxo-l-pyrrolidinyl)-2H-benzo(b)pyran-3-ol Starting from 6—formyl—7—methoxy—2,2-dimethy1-2H—chro- mene [prepared according to the method of S. Yamaguchi et al in Bull. Chem. Sc. japan, 5_7, 442 (1984)] one proceeds as described in Example 25. (+/-)—trans-3-oromo-3,4-dihydro-2,2-dimethy1-6-formy1—7- -methoxy-2H-benzo(b)pyran-4-ol M.p.: 149-151 β C NMR (CDC1 3 ): 1.45 (3H, S) , 1.65 (3H, s) , 2.93 (IH, broad), 3.88 (3H, S), 4.10 (IH, d, J=10) , 4.90 (IH, d, J=10U, 6.38 (IH, S) , 8.03 (IH, S) , 10.28 (IH, s) . (+/-)-6-Formyl-7-methoxy-3 ,4-dihydro-2,2-dimethyl-trans-4- -(2-oxo-l-pyrrolidinyl)—2H-benzo(b)pyran-3-ol M.p.: 219-221°C. NMR (CDCI3): 1.30 (3H, s) , 1.55 (3H, s) , 2.10 (2H, m) , 2.55 (2H, m) , 3.00-3.40 (2H, m) , 3.60 (3.90 (5H, m) , 5.22 (IH, d, J=10) , 6.40 (IH, s) , 7.45 (IH, s) , 10.25 (IH, s) . Example 24 Preparation of (+/-)-7—ethoxy-6-formyl-3,4-dihydro-2,2-di- methyl—trans-4-(2-oxo—l-pyrrolidinyl)-2H-benzo(b)pyran-3-ol The process as described in Example 21 is followed. M.p.: 203-206°C. NMR (CDCI 3 ): 1.30 (3H, s) , 1.45 (3H, t) , 1.55 (3H, s) , 2.10 (2H, m) , 2.55 (2H, m) , 3.00-3.40 (2H, m) , 3.60-3.80 (2H, m) , 4.08 (2H, q) , 5.22 (IH, d, J=10) , 6.38 (IH, s) , 7.45 (IH, s) , 10.30 (IH, s) . Example 25 Preparation of (+/-)-6-formyl-7-propyloxy-3,4-dihydro-2,2- -dimethyl-trans-4-(2-oxo-l—pyrrolidinyl)-2H-benzo(b)pyran-3- -ol The process as described in Example 21 is followed. M.p.: 190-192°C. NMR (CDCI3): 1.05 (3H, t) , 1.30 (3H, s) , 1.55 (3H, S) , 1.85 (2H, m) , 2.10 (2H, m) , 2.55 (2H, m) , 3.00-3.40 (2H, m) , 3.60-3.80 (2H, m) , 3.95 (2H, q) , 5.22 (IH, d, J=10) , 6.38 (IH, S), 7.45 (IH, S), 10.32 (IH, s) . Example 26 Preparation of (+/-)-(3, -dihydro-2,2-dimeth 1-7-πnethoxy- -trans-4-(2-oxo-l-pyrrolidonyl)-2H-benzo(b)pyran-3-ol-6-yl)- -propane carbonitrile 5.00 g (19.8 mmoles) of 6—formyl—4—chloro-7-methoxy—2,2- -dimethyl—2H—chromane are dissolved at room temperature in 100 ml of acetonitrile. Then 2.70 g (23.3 mmoles) of 97% potassium tert-butoxide are added and the reaction mixture is boiled under reflux for 1 hour. The reaction mixture is then evaporated and poured onto 200 g of crushed ice, extracted three time with 50 ml of chloroform each, the chloroformic solution is dried and evaporated to obtain 2- —(2,2—dimethyl—4—chloro-7-methoxy—2H—chromene-6—yl)—trans- —propene carbonitrile in the form of a yellow oil. NMR (CDC1 3 ): 1.48 (6H, S) , 3.85 (3H, s) , 5.70 (IH, s) , 5.95 (IH, d, J=17), 6.40 (IH, S) , 7.42 (IH, S) , 7.55 (IH, d, J=17) . The 2—(2,2—dimethyl—4—chloro-7—methoxy—2H-chromene—6- —yl)—trans-propene carbonitrile is dissolved in 25 ml of acetonitrile and 10 ml of 70% perchloric acid are added thereto. The reaction mixture is let to react at 40°C for an hour. It is then cooled with ice, poured onto 200 g of crushed ice, extracted with chloroform, dried on sodium sul¬ fate and evaporated. The evaporation residue is dissolved in 15 ml of methanol and cooled down to obtain 0.97 g of white crystalline trans-2—(2,2-dimethy1—7-methoxy-4-chromanone-6- —yl)—propene carbonitrile. M.p.: 127-129°C. NMR (CDCI 3 ): 1.48 (6H, s) , 2.71 (2H, s) , 3.93 (3H, s) , 6.00 (IH, d, J=17) , 6.42 (IH, s) , 7.52 (IH, d, J=17) , 7.95 (IH, S). 0.95 g (3.45 mmoles) of trans—2,2-dimethy1—7—methoxy—4- —chromanone-6—yl)—propene carbonitrile are dissolved in 30 ml of acetone, 0.10 g of 10% palladium on charcoal catalyst are added thereto and the reaction mixture is reduced at a pressure of 5.0 bar for 4 hours. Then the catalyst is fil¬ tered off and the solution is evaporated to obtain white crystalline 6—β—cyanoethyl—7-methoxy-2,2—dimethyl—4-chroma- none in a yield of 97%. M.p.: 105-107°C. NMR (CDC1 3 ): 1.45 (6H, S) , 2.60 (2H, t) , 2.68 (2H, s) , 2.90 (2H, S) , 3.87 (3H, s) , 6.38 (IH, s) , 7.65 (IH, s) . Further one proceeds as described in Example 15 to obtain white crystalline (+/-)-(3,4—dihydro-2,2—dimethyl-7- -methoxy—trans-4—(2-oxo-l—pyrrolidonyl)—2H—benzo(b)pyran—3- —ol—6—y1)—propane carbonitrile. M.p.: 180-182°C. NMR (CDCI3): 1.18 (3H, S) , i.50 (3H, S) , 2.08 (2H, m) , 2.58 (4H, m) , 2.65 (IH, m) , 2.95 (IH, m) , 3.23 (2H, m) , 3.50 (IH, m) , 3.70 (IH, m) , 3.78 (3H, s) , 5.20 (IH, d, J=10) , 6.25 (IH, S) , 6.25 (IH, S), 6.73 (IH, s) . Example 27 Preparation of (+/-)-(3,4-dihydro-2,2-dimethy1-7—ethoxy- —trans-4—(2-oxo-l-pyrrolidonyl)-2H-benzo(b) yran-3-ol-6-yl)- —propane carbonitrile The process as described in Example 25 is followed. M.p.: 208-210°C. NMR (CDCI 3 ): 1.28 (3H, s) , 1.40 (3H, t) , 1.50 (3H, s) , 2.08 (2H, m) , 2.60 (5H, m) , 3.68 (IH, m) , 2.95 (IH, m) , 3.25 (2H, m) , 3.73 (2H, m) , 4.00 (2H, q) , 5.23 (IH, d, J=10) , 6.35 (IH, S) , 6.73 (IH, S) . Example 28 Preparation of (+/-)-6-cyano-7-methoxy-3,4-dihydro-2,2-di- ethyl-trans-4-(2-oxo-l-pyrrolidinyl)-2H-benzo(b) yran-3-ol 1.52 g (10.0 mmoles) of resacetophenone are dissolved in 1.20 g (14.0 mmoles) of diethyl ketone, then 1.42 g (20.0 mmoles) pyrrolidine [prepared according to the method of H. J. Kabbe in Synthesis, 886 (1978) ] are added thereto. The reaction mixture is allowed to stand at room temperature for 24 hours, then 40 ml of toluene are added. The reaction mix¬ ture is boiled under reflux for 10 hours by using a water separator. Then it is cooled back, washed subsequently with 10% hydrochloric acid and water, thereafter it is dried and evaporated to obtain 1.41 g of 2,2-diethy1—7-hydroxy-4—chro¬ manone in the form of a pale yellow viscous oil which crys¬ tallizes on standing. M.p.: 97-99°C. NMR (CDC1 3 ): 0.92 (6H, t) , 1.75 (4H, m) , 2.68 (2H, s) , 6.38 (IH, d, J=2), 6.50 (IH, dd, Jι=2, J 2 =8.5), 7.78 (IH, d, J 2 =8.5) . 1.41 g (6.40 mmoles) of 2,2-diethy1—7—hydroxy—4-chroma- none thus obtained is methylated with methyl iodide accord- ing to the method of T. Timor et al [Acta Chi ica Hungarica, 125(2), 303 (1980)] to obtain 1.36 g of 2,2-diethy1-7-meth- oxy—4—chromanone in the form of a pale yellow oil. NMR (CDCI 3 ): 0.95 (6H, t) , 1.75 (4H, m) , 2.75 (2H, s) , 3.80 (3H, S) , 6.40 (IH, d, Jι=2), 6.55 (IH, dd, J χ =2, J 2 =8.5), 7.75 (IH, d, J 2 =8.5) . Furtheron one proceeds as described in Example 15 to obtain 6—cyano—7—methoxy—3,4—dihydro—2,2-diethy1—trans—4-(2- —oxo—1—pyrrolidinyl)—2H—benzo(b)pyran—3-ol in the form of a white crystalline substance. M.p.: 193-195°C. NMR (CDCI3) : 0.90 (3H, t) , 1.05 (3H, t) , 1.60-2.20 (6H, multiplet) , 2.55 (2H, m) , 3.05 (IH, m) , 3.30-3.60 (2H, multiplet) , 3.70 (IH, d, J=10) , 3.85 (3H, s) , 3.90 (IH, m, changeable), 5.30 (IH, d, J=10) , 6.42 (IH, s) , 7.10 (IH, s) . Example 29 Preparation of (+/-)-6-cyano-7-ethoxy-3, -dihydro-2,2-di¬ ethy1-trans— -(2-oxo-l— yrrolidinyl)—2H-benzo(b)pyran-3-ol The process as described in Example 27 is followed. M.p.: 187-189°C. NMR (CDC1 3 ): 0.90 (3H, t) , 1.05 (3H, t) , 1.45 (3H, t) , 1.70- 2.10 (6H, multiplet), 2.55 (2H, m) , 3.05 (IH, m) , 3.40 (IH, m) , 3.95-4.10 (4H, multiplet), 5.30 (IH, d, J=10) , 6.40 (IH, s) , 7.10 (IH, S) . Biological Examples 1. Measuring the bandage to potassium canal and select¬ ivity on isolated arteria mesenterica anterior of rabbits The measurements were carried out by adapting the methods of R. P. Hof et al (Circulation Research, 1988, 62 ^ , 679) and J. C. Clapham et al (J. Auton. Pharmac. , 1987, 7, 233) . Rabbits of both sexes weighing 2000-2500 g were anesthe¬ tized by a hit at the nape, the abdominal wall was cut open and the arteria mesenterica anterior was mounted after exsanguination. The artery was put into a Krebs solution of a temperature of 37°C infiltrated with carbogene while removing the interstitial residues. Then a 2 mm wide spiral is cut from the artery and this artery stripe is pre- stretched in an organ pot in Krebs solution of a temperature of 37°C, infiltrated with carbogene, by a stretching of 0.5 g- In the experiment Hugo Basile type dynamometer heads, Hugo Basile type amplifiers and Perkin Elmer type potentio¬ meter have been used for amplifying and fixing the signs. Two parallel organs were used for the qualitative tests. One of them was contracted by adding 30 mmoles of KCl after an incubation time of 1 hour, the other one by 5 μmoles of adrenaline. Then the arteries were relaxed by the cumulative addition of the substance to be examined. The system was washed with a Krebs solution containing 30 mmoles of tetra- ethyl ammonium bromide (TEA) and the organs were incubated for 30 minutes in a TEA-containing medium. After incubation the organs were again contracted with potassium and noradre- naline and a dilatation was induced by using the substance to be examined. In a quantitative test organs contracted with 5 μ oles of noradrenaline were relaxed with the sub¬ stance to be examined and the dose inducing a 50% dilatation was determined. Compound pA 2 Selectivity Mechanism of effect BRL 34915 Example 1 Example 9 Example 10 Example 11 Example 15 The compounds according to the other Examples have also been examined and found to be effective. It has been recognized that the compounds of the general formula (I) can be used for treating different types of hypertension such as essential hypertension or secondary hypertension (of renal or hormonal origin) or any other disease requiring the decrease of the blood pressure by an antihypertensive composition. 2. Decrease of blood pressure on normotensive rats meas¬ ured by a bloody method Wistar rats of both sexes weighing 230-260 g were used in the experiments. The rats were narcotised by 40 mg/kg of pentobarbital. The trachea was mounted and a polyethylene canula was introduced into the trachea, vena jugularis sinester and to the arteria carotis communis sinester. The substances to be examined were introduced into the organism of the animal through the duodenum. The pulsatory, systolic and diastolic blood pressure and the pulse were continuously measured by using a Statham type tensio eter head and haemo- dynamic measuring system produced by the Hungarian firm Experimetria Kft. After the blood pressure has become stable 0.75 μg of adrenaline were administered intravenously to measure the effect of alpha-adrenerg receptors on the blood pressure. After the hypertension has ceased 0.1 μg/kg of isoproterenole is added in order to characterize the activ¬ ity of the β-adrenerg receptors. After tachycardia has ceased the test compound was administered i.d. and the treatment with the receptor stimulants was repeated after an hour in order to characterize the effect of the test com¬ pound on adrenerg receptor subclasses. Change of the blood pressure on normotensive rats measured by bloody methods on six test animals

Claims: What we claim is: 1. Process for the preparation of the compounds of the general formula wherein R l stands for a Cι_ 6 alkyloxy, alkenyloxy, alkynyloxy, cyc¬ loalkyloxy, aryloxy, aralkyloxy, hydroxy, nitro, cyano, formyl, Cι_gacyl or Cι_ alkylcyano group or a halo atom, R 2 stands for a Cι_ 6 alkyloxy, cycloalkyoxy, aryloxy, aral¬ kyloxy group, Rl and R 2 together stand for alkylenedioxy, and R 3 and R 4 stand for a Cι_galkyl group, characterized by reducing a 4—chromanone of the general for¬ mula (XVIII) wherein R l stands for a C _galkyloxy, alkenyloxy, alkynyloxy, cyc- loalkyloxy, aryloxy, aralkyloxy, hydroxy, nitro, cyano, formyl, C _gacyl or C _galkylcyano group or a halo atom, R 2 stands for a Cι_ 6 alkyloxy, cycloalkyloxy, aryloxy, aral¬ kyloxy group, Rl and R 2 together stand for alkylenedioxy, and R 3 and R4 stand for a C _galkyl group, with metal hydrides into a 4-chromanol derivative of the general formula boiling said 4—chro anol derivative of the general formula (XIX) in a water immiscible solvent forming with it an azeo- tropic mixture in the presence of a catalytic amount of p- toluene sulfonic acid for the preparation of 2H-chromene of the general formula converting said 2H—chromene of the general formula (V) into a bromohydrine of the general formula with N—bromosuccinimide, then reacting said bromohydrine derivative of the general formula (VII) with 2—pyrrolidone in the presence of alkali metal alcoholates. 2. Process for the preparation of compounds of the gen¬ eral formula (I) , wherein R stands for a Cι_ 6 alkyloxy, cycloalkyloxy, aryloxy, aral¬ kyloxy, hydroxy, nitro, cyano, formyl, Cι_ 6 acyl or Cι_ 6 - alkylcyano group or a halo atom, R 2 stands for a hydroxy group and R3 and R4 stand for a Cι_galkyl group, characterized by hydrogenating compounds of the general for- ula (I) , wherein Rl stands for a Cι_galkyloxy, cycloalkyloxy, aryloxy, aral¬ kyloxy, hydroxy, nitro, cyano, formyl, Cι_gacyl or Cι_g- alkylcyano group or a halo atom, R 2 stands for an aralkyloxy group and R 3 and R4 stand for a Cι_ 6 alkyl group, in the presence of a catalyst under pressure. 3. Process for the preparation of compounds of the gen¬ eral formula (I) , wherein Rl stands for a Cι_ 6 alkyloxy, alkenyloxy, alkynyloxy, cyc- loalkyloxy, aryloxy, aralkyloxy, hydroxy, nitro, cyano, formyl, Cι_gacyl or Cι_galkylcyano group or a halo atom, R 2 stands for an alkenyloxy or alkynyloxy group and R 3 and R4 stand for a Cι_galkyl group, characterized by reacting a compound of the general formula (I) , wherein Rl stands for a Cι_ 6 alkyloxy, alkenyloxy, alkynyloxy, cyc¬ loalkyloxy, aryloxy, aralkyloxy, hydroxy, nitro, cyano, formyl, Cι_gacyl or Cι_galkylcyano group or a halo atom, R 2 stands for a hydroxy group and R 3 and R4 stand for a Cι_ 6 alkyl group, with suitable alkenyl or alkynyl halogenides in the presence of an acid binding agent and a catalytic amount of potassium iodide. 4. Process for the preparation of compounds of the gen- eral formula wherein Rl stands for a nitro group, R 2 stands for a Cι_ 4 alkyloxy group and R 3 and R4 stand together for a Cι_ 4 dialkyl group, characterized by reacting a compound of the general formula wherein R2 stands for a Cι_4alkyloxy group and R 3 and R4 together stand for a Cι_4alkyl group, with copper(II)nitrate in carboxylic anhydride. 5. Process for the preparation of compounds of the gen¬ eral formula wherein R l stands for a cyano group, R2 stands for a Cι_4alkyloxy group and R 3 and R4 together stand for a Cι_4alkyl group, characterized by reacting a compound of the general formula (IX) , wherein R2 stands for a Cι_4alkyloxy group and R 3 and R4 together stand for a Cι_4alkyl group. in a mixture of phosphorous trichloride oxide and dimethyl formamide to obtain a derivative of the general formula dissolving said compound of the general formula (XI) in carboxylic acid and boiling the mixture in the presence of an alkali metal formiate. 6. Process for the preparation of compounds of the gen¬ eral formula wherein R l stands for a Cι_ 4 alkylcyano group, R 2 stands for a Cι_ 4 alkyloxy group and R 3 and R4 stand together for a Cι_4alkyl group, characterized by condensing a compound of the general for¬ mula (XI) , wherein R stands for a Cι_4alkyloxy group and R 3 and R 4 stand together for a Cι_ 4 alkyl group, with acetonitrile in the presence of an alkali metal alcoho- late to obtain compounds of the general formula (XIII) , reacting said compounds of the general formula (XIII) in the presence of a mineral acid to obtain a compound of the gen¬ eral formula then hydrogenating said compound of the general formula (XIV) in the presence of a catalyst under pressure. 7. Process for the preparation of compounds of the gen¬ eral formula (XVIII) wherein Ri stands for a hydrogen atom, R 2 stands for a hydroxy group and R 3 and R4 stand together for a C 2 _ 6 alkyl group, characterized by reacting a resacetophenone of the formula with dialkyl ketone in the presence of a cyclic secondary amine in a water-immiscible solvent forming an azeoptropic mixture with same. 8. Process according to claim 1, which comprises per- forming the reduction with sodium tetrahydroborate. 9. Process according to claim 1, which comprises per¬ forming the reaction of the bromohydrine derivative of the general formula (VII) in the presence of potassium tert-but- oxide. 10. Process according to claim 2, which comprises using as catalyst palladium on charcoal. 11. Process according to claim 3, which comprises per¬ forming the reaction in the presence of potassium carbonate. 12. Benzopyran derivatives of the general formula wherein Rl stands for a Cι_ 6 alkyloxy, alkenyloxy, alkynyloxy, cyc¬ loalkyloxy, aryloxy, aralkyloxy, hydroxy, nitro, cyano, formyl, Cι_gacyl or Cι_galkylcyano group or a halo atom, R2 stands for a Cι_galkyloxy, alkenyloxy, alkynyloxy, cyc¬ loalkyloxy, aryloxy, aralkyloxy or hydroxy1 group, R l and R2 together stand for alkylenedioxy, and R 3 and R 4 stand for a Cι_ 6 alkyl group. 13. Compounds of the general formula wherein Rl stands for a nitro group, R2 stands for a Cι_ 4 alkyloxy group and R 3 and R4 stand together for a Cι_ 4 dialkyl group. 14. Compounds of the general formula wherein R l stands for a cyano group, R 2 stands for a Cι_4alkyloxy group and R 3 and R4 together stand for a Cι_4alkyl group. 15. Compounds of the general formula wherein R l stands for a Cι_4alkylcyano group, R2 stands for a Cι_4alkyloxy group and R 3 and R4 stand together for a Cι_4alkyl group. 16. Compounds of the general formula (XVIII) , wherein Rl stands for a hydrogen atom, R2 stands for a hydroxy group and R 3 and R4 stand together for a C2_galkyl group. 17. (+/-)—6,7—Dimethoxy—3,4-dihydro—2,2-dimethy1—trans- —4—(2—oxo—1—pyrrolidonyl)—2H—benzo(b)pyran—3-ol, (+/-)—6—methoxy—7—ethoxy—3,4—dihydro-2,2—dimethyl—trans- —4—(2—oxo-1—pyrrolidonyl)-2H—benzo(b)pyran—3-ol, (+/-)—6—ethoxy—7—methoxy—3,4-dihydro—2,2-dimethy1—trans- - 41 - -4-(2-oxo-l-pyrrolidinyl)-2H-benzo(b)pyran-3-ol, (+/-)-6-methoxy-7-benzyloxy-3,4-dihydro-2,2-dimethy1- -trans-4-(2-oxo-l-pyrrolidinyl)-2H-benzo(b)pyran-3-ol, (+/-)—6-methoxy—7-hydroxy-3,4-dihydro-2 ,2-dimethy1- -trans-4—(2-oxo-l-pyrrolidinyl)-2H-benzo(b)pyran-3-ol, (+/-)—6,7-dibenzyloxy-3,4-dihydro-2,2-dimethyl-trans-4- —(2-oxo-l-pyrrolidinyl)-2H-benzo(b)pyran-3-ol, (+/-)—6,7-dihydroxy-3,4-dihydro-2,2-dimethyl-trans-4-(2- -oxo-1-pyrrolidinyl)-2H-benzo(b)pyran-3-ol, (+/-)—6,7-methylenedioxy-3,4-dihydro-2,2—dimethyl—trans- -4—(2-oxo-l-pyrrolidinyl)-2H-benzo(b)pyran-3-ol, (+/-)—6—bromo-7—methoxy-3,4-dihydro-2,2-dimethy1—trans- -4-(2-oxo-l-pyrrolidinyl)-2H-benzo(b)pyran-3-ol, (+/-)—6-chloro-7—methoxy-3,4-dihydro-2,2-dimethy1—trans- -4—(2-oxo-l-pyrrolidinyl)-2H-benzo(b)pyran-3-ol, (+/-)—6—nitro—7—methoxy-3, -~dihydro-2,2-dimethy1—trans- —4—(2—oxo-l—pyrrolidinyl)-2H-benzo(b)pyran—3-ol, (+/-)—6—nitro—7—ethoxy-3,4-dihydro-2,2-dimethy1—trans—4- —(2—oxo—1—pyrrolidinyl)—2H-benzo(b)pyran—3-ol, (+/-)—6—nitro-7—propyloxy-3,4-dihydro-2,2-dimethy1- —trans—4—(2—oxo—1—pyrrolidinyl)—2H-benzo(b)pyran-3-ol, (+/-)—6-nitro-7—isopropyloxy-3,4-dihydro-2,2-dimethy1- — rans—4—(2—oxo-l—pyrrolidinyl)-2H-benzo(b)pyran-3-ol, (+/-)—6—cyano—7—methoxy-3,4-dihydro-2,2—dimethyl—trans- —4—(2—oxo—1—pyrrolidinyl)—2H-benzo(b)pyran—3-ol, (+/-)—6—cyano—7—ethoxy—3,4-dihydro—2,2—dimethyl—trans—4- —(2—oxo-l—pyrrolidinyl)-2H-benzo(b)pyran-3-ol, (+/-)—6-cyano—7-propyloxy-3,4-dihydro-2,2-dimethy1- —trans— —(2-oxo-l—pyrrolidinyl)-2H-benzo(b)pyran—3-ol, (+/-)—6-cyano—7-(1—methylethoxy)-3,4-dihydro-2,2-di¬ methyl-trans-4-(2-oxo-l-pyrrolidiny1)-2H-benzo(b)pyran-3-ol, (+/-)—6—cyano—7—(1—methylpropyloxy)—3,4-dihydro-2,2-di¬ methy1—trans—4—(2—oxo—1—pyrrolidinyl)-2H—benzo(b)pyran—3-ol, (+/-)—7—benzyloxy—6-cyano—3,4-dihydro—2,2—dimethyl- -trans-4-(2-oxo-l-pyrrolidinyl)-2H-benzo(b)pyran-3-ol, (+/-)-7-hydroxy-6-cyano-3,4-dihydro-2,2-dimethy1-trans- -4-(2-oxo-l-pyrrolidinyl)-2H-benzo(b)pyran-3-ol, (+/-)-7—allyloxy—6-cyano—3,4-dihydro-2,2-dimethy1-trans- —4—(2-oxo-l-pyrrolidinyl)—2H-benzo(b)pyran-3-ol, (+/-)—6—formyl—7—methoxy—3,4—dihydro-2,2-dimethy1-trans- —4—(2—oxo-l—pyrrolidinyl)—2H—benzo(b)pyran-3-ol, (+/-)—7—ethoxy—6—formyl—3,4—dihydro-2,2-dimethy1—trans- —4—(2—oxo—1-pyrrolidinyl)—2H—benzo(b)pyran—3-ol, (+/-)—6-formyl-7—propyloxy-3,4-dihydro-2,2-dimethyl- —trans-4—(2—oxo-l—pyrrolidinyl)—2H—benzo(b)pyran—3-ol, (+/**)—(3,4-dihydro-2,2—dimethyl—7-methoxy—trans—4—(2- —oxo-l—pyrrolidonyl)—2H—benzo(b)pyran-3—ol—6-yl)—propane carbonitrile (+/-)—(3,4—dihydro-2,2-dimethy1—7—ethoxy—trans—4—(2-oxo- —1—pyrrolidonyl)—2H—benzo(b)pyran—3—o1—6—yl)—propane carbonitrile (+/-)—6-cyano—7—methoxy-3,4-dihydro-2,2-diethy1—trans-4- —(2—oxo-l—pyrrolidinyl)-2H—benzo(b)pyran-3-ol and (+/-)—6—cyano—7—ethoxy—3,4-dihydro-2,2-diethy1—trans-4- —(2—oxo-l—pyrrolidinyl)—2H—benzo(b)pyran-3-ol. 18. Process for the preparation of a pharmaceutical com¬ position for the treatment of hypertension, asthma, diseases of the urinary organs, heart failure, diseases of the central nervous system and paralysis, characterized by admixing a compound of the general formula (I) , wherein Ri, R2, R and R4 are as defined in claim 12 to pharmaceutically acceptable carriers and/or auxiliaries. 19. Pharmaceutical composition for the treatment of hypertension, asthma, diseases of the urinary organs, heart failure, diseases of the central nervous system and para¬ lysis, characterized containing a compound of the general formula (I) , wherein Ri, R2, R 3 and R4 are as defined in claim 12.

Inventors: BARTIK TAMAS, ESZENYI TIBOR, FRANK LASZLO, PAPP GYULA, SEBOEK PETER, TIMAR TIBOR, BARTIK, TAMAS, ESZENYI, TIBOR, FRANK, LASZLO, PAPP, GYULA, SEBOEK, PETER, TIMAR, TIBOR
Applicants: ALKALOIDA VEGYESZETI GYAR, BARTIK TAMAS, ESZENYI TIBOR, FRANK LASZLO, PAPP GYULA, SEBOEK PETER, TIMAR TIBOR, ALKALOIDA VEGYESZETI GYAR RT., BARTIK, TAMAS, ESZENYI, TIBOR, FRANK, LASZLO, PAPP, GYULA, SEBOEK, PETER, TIMAR, TIBOR
Application year: 1993
Main classification: C07D405
IPC codes: A61K31, A61P9, A61P11, A61P13, A61P15, A61P25, C07D311, C07D405