bluuebunny/crossref_metadata_2025_split huggingface dataset:
Chemistry of thienopyridines. XIX. Further studies on chlorination and S‐oxidation in the thieno[2,3‐b] pyridine system
Authors: Klemm L. H. , Merrill K. K. , Lee F. H. W. 
Published: April 2009

AbstractTreatment of thieno [2,3‐b] pyridine (1a) with chlorine gas in chloroform (plus water) gave a mixture of two 2,3‐dichloro‐2,3‐dihydrothieno[2,3‐b] pyridine 1‐oxides [trans‐syn (IIa), and cis‐anti (IIb)) [and 2,3,3‐trichloro‐2,3‐dihydrothieno[2,3‐b]pyridine syn‐1‐oxide (IVa), as well as a non‐isolated fourth product (prohably the anti isomer of IVa) and sometimes a small amount of thieno[2,3‐b]pyridine 1,1‐dioxide (III). Treatment of Ia in a solvent (water, chloroform‐water, or THF‐water) with sulfuric acid and sodium hypochlorite gave a mixture of IIb and III. Effects of variations of reaction conditions on the composition of the product mixture were ascertained through chemical isolation and/or pmr analysis. Products formed were rationalized in terms of the chlorine‐water‐hypochlorous acid equilibrium, plus attack of chlorine variously at positions 1 (S‐atom), 2, and 3 of 1a, but of hypochlorous acid only at position 1. Thermal and chromatographic limitations on isolation procedures for some of the products were established. Stereochemistries of IIa, IIb, and IVa were assigned by means of pmr spectrometry with the aid of the shift reagent Eu(fod)3. Spin‐spin couplings between the proton at position 2 and those at positions 4 and 6 were observed at high resolution.In exploratory runs, 5‐ethyl‐la was converted into isolable 2,3‐dichloro‐5‐ethyl‐2,3‐dihydrothieno[2,3‐b]pyridine 1‐oxide, and 5‐acetyl‐Ia yielded 3‐chloro‐5‐acetylthieno] 2,3‐b]pyridine. Mass spectral fragmentation patterns for the various products are presented.
Synthesis and antimicrobial activity of 4‐aza‐5α‐sitostane and the 4‐methyl derivative
Authors: Aboul‐Enein Hassan Y. , Doorenbos Norman J. 
Published: April 2009

AbstractSynthesis of 4‐aza‐5α‐sitostane (IX), and 4‐methyl‐4‐aza‐5α‐sitostane (XII) were accomplished through a set of reactions involving oxidative opening of ring A of α,β‐unsaturated ketone, ring closure, followed by catalytic hydrogenation and lithium aluminum hydride reduction, respectively. The antimicrobial activity for X and XII is reported.
Synthesis of 2‐[3′‐(trifluoromethyl)anilino] ‐5‐hydroxynicotinic acid
Authors: Němec Josef , Meeker Fred S. , Schreiber Eric C. 
Published: April 2009

Abstract2‐[3′‐(Trifluoromethyl)anilino]‐5‐hydroxynicotinic acid(2)was synthesized by two routes: a) by direct hydroxylation of 2‐[3′‐(trifluoromethyl)anilino]nicotinie acid(1); and b) by the following sequence starting from 2‐chloro‐3‐methyl‐5‐nitropyridine(3)via5‐amino‐2‐chloro‐3‐methylpyridine(4), 2‐ehloro‐5‐hydroxy‐3‐methylpyridine(6), 5‐acetoxy‐2‐chloro‐3‐methylpyridine(7), 5‐acetoxy‐2‐chloronicotinie acid(8), and 2‐chloro‐5‐hydroxynicotinic acid(9).The correlation of2with one of the metabolites of1has been accomplished, and the identities of both compounds have been proven.
Acid catalyzed rearrangements of thia and aza analogs of adamantanes a new derivative of sulfamide, formaldehyde and ammonia
Authors: Thyagarajan B. S. , Kang J. B. 
Published: April 2009

AbstractThe conversion of 2‐thia‐1,3,5,7‐tetraazatricyclo[3.3.1.13,7] decane 2,2‐dioxide under acid conditions into a hexaazatetracyelo derivative is described.
Hydroxymethylphenylnaphthoie acid lactones
Authors: Ahmed Riaz , Holmes T. L. , Stevenson Robert 
Published: April 2009

AbstractReduction of 1‐phenylnaphthalene‐2,3‐dicarboxylic anhydride (I) with zinc and acetic acid or lithium aluminium hydride yields a mixture of 1‐phenyl‐3‐hydroxymethyl‐2‐naphthoie acid lactone (II) and 1‐phonyl‐2‐hydroxymethyl‐3‐naphthoie acid lactone (III). Catalytic hydrogenation of (I) gave the tetrahydronaphthalene dicarboxylic anhydride (IV). Oxidation of the phenyldihydronaphthofuran (X), prepared by base‐catalyzed cyclization of the ether (IX), also yielded lactones (II) and (III). The phenyltetrahydronaphthofuran (XII) was similarly prepared by cyclization of the phenylpropargyl cinnamyl ether (XI).
Synthesis of unsymmetrical 2,4‐dialkylpyrazolo[1,5‐a]‐1,3,5‐triazines
Authors: Novinson Thomas , Senga Keitaro , Kobe Jože , Robins Roland K. , O'Brien Darrell E. , Albert Anthony A. 
Published: April 2009

AbstractThe reaction of 3‐aminopyrazole with imidate esters such as ethyl acetimidate, gave N‐(pyrazol‐3‐yl)acetamidine (1) rather than the isomeric 2‐acetamidoyl‐3‐aminopyrazole. Ring closure of 1 with orthoesters such as ethyl propionimidate, afforded unsymmetrically substituted 2.4‐dialkylpyrazolo[1,5‐a]‐1,3,5‐triazines such as 4‐ethyl‐2‐methylpyrazolo[1,5‐a]‐1,3,5‐triazine (3). The structure of 1 was confirmed by several alternate syntheses. The unique feature of this two‐step synthetic approach to the synthesis of pyrazolo[1,5‐a]‐1,3,5‐triazines is that it is a convenient method of preparing fused triazines based on available pyrazoles rather than the less accessible dialkyltriazines.
Syntheses of 5H‐benzoxazolo[3,2‐a] quinolin‐5‐ones
Authors: Kim Dong Han , Fieber Richard A. , Santilli Arthur A. , Bell Stanley C. 
Published: April 2009

AbstractTreatment of N‐(2‐hydroxyphenyl)anthranilic acid with acetic anhydride, under refluxing conditions provided a simple method for the synthesis of 5H‐henzoxazolo[3,2‐a] quinolin‐5‐one (IVa), a heretofore unreported ring system. When propionic anhydride was used in the above reaction, 6‐methyl‐5H‐benzoxazolo[3,2‐a]quinolin‐5‐one (Va) was obtained. Other examples prepared in this fashion were IVb, IVc and Vb. Treatment of IVa with methoxyethylamine afforded 1,2‐dihydro‐1‐(2‐hydroxyphenyl)‐2‐(methoxyethylimino)‐4‐quinolinol (VII). A possible mechanism for the cyclization reaction is discussed.
Synthesis of diimidazo[1,2‐a:2′,1′‐c]pyrazines and diimidazo[1,2‐a:2′,1′‐c] [1,4]diazepines
Authors: Melloni P. , Fusar‐Bassini D. , Dradi F. , Confalonieri C. 
Published: April 2009

AbstractTwo new heterocyclic compounds, diimidazo[1,2‐a:2′,1‐c]pyrazine and 5H‐diimidazo[1,2‐a: 2,1′‐c][1,4]diazepine have been synthesized by various routes from 2,2′‐biimidazole (1) (2) together with some hydro, hydroxy and alkyl derivatives.
A novel synthesis of a benzimidazo[1,2‐c]benzopyrimidine by photolysis of 4‐(benzotriazol‐1‐yl‐2‐phenylquinazoline
Authors: Hubert A. J. 
Published: April 2009

AbstractA novel synthesis of 6‐phenylbenzimidazo[1,2‐c]benzopyrimidine (5) by photolysis of 4‐(benzolriazol‐1‐yl‐2‐phenylquinazoline (3) is described. The acid‐catalysed thermolysis of 3 leads to an extensive degradation yielding 2‐pbenyl‐4‐quinazolinone (4).
1,2,4‐Triazincs XIII. The bond lengths and bond angles of a 1,2,4‐triazine
Authors: Atwood J. L. , Krass D. K. , Paudler William W. 
Published: April 2009

AbstractThe bond distances and bond angles of 5‐(p‐chlorophenyl)‐1,2,4‐triazine determined by three dimensional X‐ray crystallographic analysis are reported. The pertinent bond lengths are N1N2, 1.335Å, N2‐C3, 1.314Å, C3N4, 1.339; N4‐C5, 1.317; C5‐C6, 1.401; C6N1, 1.317Å. A comparison of these bond distances with those of similar polyazabenzenes shows that the canonical structure of 1,2,4‐triazine with a N1N2 single bond more closely represents the ground state of this ring system, than the one with a N1N2 double bond.
1,2,4‐Triazino[4,3‐c]‐ and [2,3‐c]quinazolines
Authors: Trepanier Donald L. , Sunder Shyam , Braun Werner H. 
Published: April 2009

AbstractThis paper describes the reactions of 2‐o‐aminophenyl‐1,4,5,6‐tetrahydro‐1‐methyl‐1,2,4‐triazine with a variety of reagents to give substituted 1,2,4‐triazino[4,3‐c]quinazolines or 1,2,4‐triazino[2,3‐c]quinazolines. Certain representative compounds of these two new heterocyclic systems were characterized by the tlc, ir, nmr, mass spectra, and identified by unequivacol synthesis.
Polarography of some 2,1,3‐benzothiadiazoles, benzofurazans, 2,1,3‐benzoselenadiazoles, and 3,4‐disubstituted and fused 1,2,5‐thiadiazoles
Authors: Sherman E. O. , Lambert S. M. , Pilgram K. 
Published: April 2009

AbstractThe redox behavior has been determined in acetonitrile solutions at a mercury and platinum electrode for 2,1,3‐benzo(group VI)diazoles, and 3,4‐disubstituted and fused 1,2,5‐thiadiazoles. The derivatives studied contained alkyl, phenyl, bromo, chloro, cyano, nitro, methylsulfonyl, and trifluoromethylsulfonyl groups. All ring systems and their derivatives are reversibly reduced initially in a one‐electron step, to their respective radical anion, but the nitro and bromo derivatives are reduced preferentially at the substituent group. The potential at which the production of the radical anion occurred became more anodic as the electron withdrawing ability of the substituent and the number of substituents increased.
Hétérocyclisations intramoléculaires par réaction d'oxymercuration. I — synthèse et configurations des hétérocycles
Authors: Speziale V. , Roussel J. , Lattes A. 
Published: April 2009

AbstractL'oxyrnercuration intramoléculaire cyelisante d'alcools γ‐δ éthyléniques a été réalisée afin d'en étudier la stéréochimie. Le rǒle de la nature du sel mercurique, de l'alcool et des conditions opératoires a été examiné. La réduction in situ des organomercuriques conduit parfois à des proportions de diastéréoisomères différentes de cellos obtenues à partir des produits isolés, qui ne subissent pas de changement de configurations au cours de cette étape.
Synthesis of 2,1,3‐benzothiadiazolecarbonitriles
Authors: Pilgram K. , Skiles R. D. 
Published: April 2009

Abstract2,1,3‐Benzothiadiazolecarbonitriles, 2, have been prepared by two different methods. Reaction of bromo‐2,1,3‐benzothiadiazoles, 1, with cuprous cyanide occurs advantageously in refluxing dimethylformamide to give 2, complexed with curpous bromide. Hydrogen peroxide in hydrochloric acid at 30–40° is shown to be an effective reagent for efficient decomposition of these reactions complexes, 2 CuBr, and subsequent isolation of 2. Yields in the Sandmeyer method for preparing nitriles 2 were improved by diazotizing amino‐2,1,3‐benzothiadiazoles, 3, with nitrosyl‐sulfuric acid prior to reaction with the cuprous‐sodium cyanide complex.
Syntheses and properties of 3‐acylimino‐1‐alkylimidazolium and benzimidazolium betaines
Authors: Tamura Yasumitsu , Hayashi Hironori , Minamikawa Jun‐Ichi , Ikeda Masazumi 
Published: April 2009

Abstract3‐Amino‐1‐alkylimidazolium and benzimidazolium mesitylenesulfonates were readily prepared in good to high yeilds by treating the parent heterocycles with O‐mesitylenesulfonylhydroxylamine. Treatment of the 3‐amine salts with acylating agents gave crystalline 3‐acylimines, which showed the characteristic ir, uv, nmr, and mass spectral properties. Deuterium exchange of the 3‐acylimines occurs at the 2‐position. Thermolysis of neat 3‐benzoylimino‐1‐rnethylbenzimidazolium betaine afforded 2‐benzamido‐1‐methylbenzimidazole and products derived from NN bond cleavage. Irradiation of 3‐benzoylimino‐1‐alkylbenzimidazoliurn betaines resulted in NN bond cleavage to give 1‐alkylbenzimidazoles and benzamide, while the corresponding 3‐ethoxycarbonylimines underwent rearrangement to afford ethyl 1‐alkyl‐2‐benzimidazolecarbamates.
The synthesis of 7‐(substituted‐amino)‐3‐azabicyclo[3.2.0] heptanes
Authors: Rynbrandt Ronald H. 
Published: April 2009

Abstract1,2‐Cycloaddition reactions of several enamines with N‐substituted maleimides and 4‐phenyl‐1,2,4‐triazoline‐3,5‐dione have been carried out. The adducts were transformed into 7‐(substituted‐amino)‐3‐azabicyclo[3.2.0]heptanes and a 1,2,4‐triazolidine‐1‐acetaldehyde, respectively. These are the first reported examples of 3‐azabicyclo[3.2.0]heptanes substituted in any position other than the 3‐position. The reaction of an ynamine with N‐benzylmaleimide afforded a bicyclic intermediate which upon hydrolysis gave a 2,5‐dioxo‐3‐pyrrolidineacetic acid.
Novel polycyclic heterocyeles. XIII. Derivatives of the oxime and carbinol derived from 1,2‐dihydro‐11‐(trifluoromethyl)‐3H,7H‐quino[8,1‐cd] [1,5]benzoxazepin‐3‐one
Authors: Yale Harry L. , Petigara Ramesh B. 
Published: April 2009

AbstractThe anions derived from the oxime, 2, and the carbinol, 3, generated by reaction with sodium hydride, were reacted with aminoalkyl chlorides and an aroyl chloride to give a number of amino‐alkyl ethers and an aroyl ester. In addition, 2 and 3 were reacted with phenylisocyanate to yield O‐phenylcarbamoyl derivatives. The pmr spectra of several of these compounds are discussed.
Synthesis of fused hydantoins by intramolecular amidoalkylation
Authors: Zaugg H. E. , Arendsen D. L. 
Published: April 2009

AbstractSeveral 1‐(2‐arylcthyl)hydantoins 2 have been cyclized through their 5‐bromo derivatives. The hydantoins 2a and 2b, unsubstituted in the 5‐posilion, require stannic chloride catalysis of the cyclization to 3a and 3b, respectively. However, the 5‐phenyl analog 2c (n = 2) cyclizes spontaneously and essentially quantitatively to 5 during bromination. This reaction is limited to the formation of a 6‐membered ring.
Synthesis and structural assignment of 5,6‐dihydro‐8‐hydroxy‐9‐methoxy‐1H,7H‐benzo[ij] quinolizine‐1,7‐dione
Authors: Wright George C. , Schwan Thomas J. , Miles Nelson J. 
Published: April 2009

AbstractThe compound 5,6‐dihydro‐8‐hydroxy‐9‐methoxy‐1H,7H‐benzo[ij]quinolizine‐1,7‐dione ( 4a) was synthesized from 3‐(1,4‐dihydro‐6,7‐dimethoxy‐4‐oxo‐1‐quinolyl)propionic acid (3a, free base), involving spontaneous demethylation with ring closure. The structural assignment of 4a was based on an analogous, unequivocal synthesis of 5,6‐dihydro‐9‐ethoxy‐8‐hydroxy‐1H,7H‐benzo[ij]quinolizine‐1,7‐dione hydrochloride (4b).
Benzomorphan analogues: Synthesis of some thieno[2,3‐f] morphans
Authors: Montzka Thomas A. , Matiskella John D. 
Published: April 2009

AbstractA series ofN‐substituted 5,9‐dimethylthieno[2,3‐f]morphans and 5‐phenylthieno[2,3‐f] ‐ morphans has been prepared starting from 3,4‐dimethylpyridine and 4‐phenylpyridine and 3‐thenylbromide by an application of the Grewe morphinan synthesis. The thieno [2,3‐f]morphans were tested for analgetic activity, but only weak analgetic activity relative to toxicity and no morphine antagonism activity was observed.
The synthesis of certain 8‐cyano‐2,4‐disubstituted‐imidazo[1,5‐a] pyrimidines
Authors: Novinson Thomas , O'Brien Darrell E. , Robins Roland K. 
Published: April 2009

AbstractA number of imidazo[1,5‐a]pyrimidine‐8‐carboxamides were synthesized by reacting various β‐dicarbonyl compounds with 5(4)‐aminoimidazole‐4(5)carboxamide (AICA,1), the non‐ribosylated form of AICAR, a key intermediate in the metabolic pathway of purine biosynthesis. Cyclization of1with ethylacetoacetate yielded 2‐methylimidazo[1,5‐a]pyrimidin‐1H‐4‐one‐8‐carboxamide (2). The treatment of2with phosphorus oxychloride gave 4‐chloro‐8‐cyano‐2‐methylimidazo[1,5‐a]pyrimidine (3). Various nucleophiles displaced the 4‐chloro substituent of3under mild conditions. However, the 4‐methylthio group of 8‐cyano‐2‐methyl‐4‐methylthioimidazo[1,5‐a)pyrimidine (8a) was also displaced under very mild conditions. Even more strangely, the 4‐diethylamino group of 8‐cyano‐4‐diethylamino‐2‐methylimidazo[1,5‐a]pyrimidine (5a) was displaced by ammonia to give 4‐amino‐8‐cyano‐2‐methylimidazo[1,5‐a]pyrimidine (7).
Photochemical functionalization of 6‐azauracils to 5‐substituted‐6‐azauracils
Authors: Swenton John S. , Balchunis Robert J. 
Published: April 2009

AbstractPhotochemical cycloaddition of 6‐azauracil derivatives to enol acetates yields hydrolytically labile bicyclic azetidines which decompose in good to excellent yield to 5‐substituted‐5,6‐dihydro‐6‐azauracils. These compounds can in turn be oxidized by bromine to the 5‐substituted‐6‐azauracil. This reaction sequence has also been applied to 2′,3′,5′‐tri‐o‐benzoyl‐6‐azauridine resulting in a 60% overall yield of the functionalized nucleoside derivative. The three‐step procedure reported here affords a simple method for carboncarbon bond formation at the 5‐position of 6‐azauracil and may be applicable to other imines systems.
Synthesis of hexahydro 1,3,5‐triCarbalkoxy‐s‐triazines, octahydro‐1,3,5,7‐tetracarbalkoxy tetrazocines and their interconvertibility
Authors: Thyagarajan B. S. , Majumdar K. C. 
Published: April 2009

AbstractThe condensations of urethanes with formaldehyde under appropriate experimental conditions affords either 1,3,5‐triazines or 1,3,5,7‐tetrazoeines. The two systems are interconvertible under acid catalysis.
Pentaatomie heteroaromatic cations. Note III . A Convenient Synthesis of Aldehydes from Carboxylic Acids via 2‐Substituted 1,3‐Benzoxathiolium Perchlorates
Authors: Costa Luigi , Degani Iacopo , Fochi Rita , Tundo Piero 
Published: April 2009

AbstractA convenient method for the preparation of aldehydes from the corresponding carboxylic acids is presented. By reaction of the carboxylic acids with o‐mercaptophenol and perchloric acid in phosphorus oxychloride, the corresponding 2‐substituted 1,3‐benzoxathiolium perehlorates were obtained. Reduction of the salts with lithium aluminium hydride in dry ether gave 2‐substituted 1,3‐benzoxathioles, which, when hydrolyzed by mercuric chloride, gave the corresponding aldehydes. Twenty five aldehydes of different structure were obtained in good yields, by a fast and simple procedure.
Potential ambifunctionality of 2‐azidopyrido[1,2‐a] pyrimidin‐4‐one
Authors: Kovačič M. , Polanc S. , Stanovnik B. , Tišler M. 
Published: April 2009

Abstract2‐Azidopyrido[1,2‐a]pyrimidin‐4‐one can exit only in the azido form and undergoes cyclo‐addition reaction with 1,3‐dicarbonyl compounds to form 1,2,3‐triazole derivatives. Under the influence of bases or hydrochloric acid the carbonyl group is attacked with subsequent opening of the pyrimidine ring. This causes an immediate cyclization of the azide group to give a tetrazolo derivative. In a similar way a triazole ring can be formed from the appropriate hydrazino derivatives of pyrido[1,2‐a]pyrimidin‐4‐one.
Dithieno‐ and thienobenzothiazines
Authors: Grol C. J. 
Published: April 2009

AbstractThe synthesis of some isomeric dithienothiazine systems has been described. These thiazines were made by an Ullman type cyclization reaction, starting with the appropriate dithienyl‐sulphides. During the ring closure reaction hydrogen chloride was eliminated from the β‐chloro‐propionyl side chain resulting in the formation of the acryloylthiazines5, 7and11. This reaction was studied under various conditions and some of the byproducts were identified. The general applicability of the reaction was demonstrated by the synthesis of two isomeric thienobenzothiazines14and16. Addition ofN‐methylpiperazine afforded the (N‐methylpiperazinyl)propionylthienothiazines, which were isolated as their hydrochloride salts. The latter compounds were tested for neuroleptic and antidepressive properties, but were shown to be devoid of activity. This lack of activity is discussed in terms of the hampered formation of the radicalcations, as was shown by the electrochemical oxidation of these compounds. Efforts to reduce the carbonyl function to give the propyl chain failed, due to an elimination of the side chain.
Polycyclic azetidines. I. The preparation of benzo [c]‐cis‐6‐azabicyclo[3.2.0] heptane
Authors: Murray Robert J. , Cromwell Norman H. 
Published: April 2009

AbstractThe title compound was prepared from compounds readily obtained from 2‐carbomethoxy‐I‐indanone oxime (5) or from the N‐chlorosulfonyl isocyanate adduct of indene (9). Apart from its ability to undergo transformation to the azetidine, compound 9 upon refluxing with excess LAII was found to undergo reductive decompostion to cis‐2‐hydroxymethyl‐1‐indanamine (2).
The chemistry of 4‐hydrazino‐7‐phenylpyrazolo[1,5‐a] ‐1,3,5‐triazines
Authors: Kobe Joze , O'Brien D. E. , Robins R. K. , Novinson Thomas 
Published: April 2009

AbstractThe reaction of 4‐hydrazino‐7‐phenylpyrazolo[1,5‐a]‐1,3,5‐triazine (4) with nitrous acid gave 8‐phenyltetrazolo[1,5‐e]pyrazolo[1,5‐a]‐1,3,5‐triazine (5b), which was determined by pmr and ir spectra to be in equilibrium with 4‐azido‐7‐phenylpyrazolo[1,5‐a]‐1,3,5‐triazine (5a). The equilibrium between the tetrazolo (5b) and azido (5a) forms was studied by pmr and an attempt was made to determine if substituents in the pyrazole nucleus could sufficiently stabilize the tricyclic tetrazolo form (5b) over the bicyclic azido form (5a). Thermal degradation of 5(a ⇌ b) in an aprotic solvent gave 4‐amino‐7‐phenylpyrazolo[1,5‐a]‐1,3,5‐triazine (7), indicating the probability of a nitrene mechanism involved in the decomposition. Heating 5 in aqueous base gave both 7 and the “hydroxy” analog, 7‐phenylpyrazolo[1,5‐a]‐1,3,5‐triazin‐4(3H)one (6), further substantiating the existence of a nitrene intermediate with a competing nucleophilic displacement of the azido group by a hydroxyl group. Cyclization of 4 with diethoxymethylacetate (DEMA) gave 8‐phenyl‐s‐triazolo[4,3‐e]pyrazolo[1,5‐a]‐1,3,5‐triazine (8), which underwent thermal rearrangement to 8‐phenyl‐s‐triazolo[2,3‐e]pyrazolo[1,5‐a]‐1,3,5‐triazine (9). Acid catalyzed ring opening of 9 with formic acid gave 3‐N‐formamido‐5‐phenyl‐2(2‐s‐triazolyl)pyrazole (10). The failure of 10 to recyclize to 9 with the resultant loss of water, supported the theory that the rearrangement of 8 to 9 might occur simply as a concerted, thermally induced “anhydrous” rearrangement rather than via a covalently hydrated intermediate or a Dimroth type mechanism (in the base catalyzed rearrangement).
The synthesis of novel dipyridazinothiazine ring systems
Authors: Wise Dean S. , Castle Raymond N. 
Published: April 2009

AbstractThe synthesis of several dipyridazinothiazines have been accomplished by: (a) cyclization in concentrated hydrochloric acid solution of the appropriate intermediates; and (b) via the Smiles rearrangement in either basic or glacial acetic acid solution of the appropriate intermediates. The following ring systems have been prepared and characterized: 10H‐dipyridazino‐[4,3‐b:4′,5′‐e]‐1,4‐thiazine, 5H‐dipyridazino[3,4‐b:4′,5′‐e]‐1,4‐thiazine, 10H‐dipyridazino[4,5‐b:‐4′,5′‐e]‐1,4‐thiazine, 5Hdipyridazino[5,4‐b:4′,3′‐e]‐1,4‐thiazine, and 10H‐dipyridazino[3,4‐b:‐3′,4′‐e]‐1,4‐thiazine.
Nitration of 2,3′‐bithienyl
Authors: Dell'Erba Carlo , Guanti Giuseppe , Garbarino Giacomo 
Published: April 2009

AbstractThe nitration of 2,3′‐bithienyl (1) with fuming nitric acid in acetic anhydride at 0° gives a mixture of 3‐nitro‐ (2), 2′ ‐nitro‐ (3) and 5‐nitro‐2,3′‐bithienyl (4) with relative percentages of 38.7%, 34.8% and 26.5%. When the nitration of 1 was carried out with fuming nitric acid in acetic acid at 20°, the same compounds 2, 3 and 4 were obtained, but with different relative percentages: 20.4%, 36.5% and 43.1% respectively. The results of the mononitration of 1 are compared with those obtained in other electrophilic substitutions and with the theoretical predictions. The further nitrations of 2, 3 and 4 with nitric acid in acetic anhydride at room temperature lead to the formation of five dinitro‐2,3′‐bithienyl isomers. Compound 2 gives a mixture of 2′,3‐dinitro‐ (5) and 3,5′‐dinitro‐2,3′‐bithienyl (6); compound 3 gives a mixture of 5, 2′,5‐dinitro‐ (7) and 2′,4‐dinitro‐2,3′‐bithienyl (8); compound 4 gives 7 and 5,5′‐dinitro‐2,3′‐bithienyl (9). The possible reasons of the formation of the various dinitro‐2,3′‐bithienyl isomers are discussed.
The synthesis of 4‐(o‐fluorophenyl)‐6,8‐dihydro‐3,8‐dimethyl‐pyrazolo[3,4‐e][1,4]diazepin‐7(IH)one, a metabolite of zolazepam
Authors: Dewald Horace A. 
Published: April 2009

AbstractA metabolite of Zolazepam was prepared by a selective N‐demethylation of a dihydro derivative of Zolazepam using pyridine hydrochloride.
Studies on the syntheses of heterocyclic compounds. Part DLXXXI . Syntheses of 3‐carboxy‐1,2,3,4‐tetrahydroisoquinoline derivatives by phenolic cyclization
Authors: Kametani Tetsuji , Kigasawa Kazuo , Hüragi Mineharu , Ishimaru Haruhide , Haga Seiji 
Published: April 2009

Abstract3‐Carboxy‐1,1‐dimethylisoquinoline and 3‐carboxy‐1‐spirocycloalkano‐and 1‐spiroheterocyclo‐alkanoisoquinoline derivatives were synthesized by phenolic cyclization reaction using m‐tyrosine and several carbonyl compounds.