Condensed benzopyrans II. Some derivatives of 3H-pyrano[3,2-f]quinoline

The reaction of 6-aminoeoumarin with some ethoxymethylene compounds and dimethyl acetylenedicarboxylate led to condensation products which on thermal cyclizations afford new derivatives of 3H-pyrano[3,2-f]quinoline (IIa-IIc).     

Synthesis and some transformations of 4H-pyrano[3,2-d]pyrazoles

The ability of the amide carbonyl group of the pyrazolone ring to participate in the heterocyclization of oxopropyl-5-pyrazolones under the influence of polyphosphoric acid (PPA) or phosphorus polysulfide in dioxane with the formation of 4H-pyrano[ 3,2-d]pyrazole derivatives is demonstrated. Ionic hydrogenation of the pyranopyrazoles leads to 5,6-dihydropyrano[3,2-d]pyrazoles, while the action of phosphorus polysulfide in xylene leads to pyrazolo[5,4-b]thiapyrylium salts.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 317–320, March, 1982.     

Synthesis of 4H-furo[3,2-b]indoles. II. Bromination,acylation and nitration of 4H- and 4-benzoylfuro[3,2-b]indoles

Monobromination and monoacylation at the 2-position of 4H-furo[3,2-b]indole ring (III) were facilitated by the benzoyl group in the 4-position; subsequent nitration attempts were unsuccessful.     

2-芳基-4-氧-4 H-吡喃酮[3,2-c]-9-溴喹啉类化合物的合成

黄酮类化合物广泛存在于埴物体中,具有广泛的生物活性,其研究发展很快,但对于氮杂黄酮类化合物的研究工作却甚少。含氮黄酮类化合物具有抗癌、抗菌、冠状动脉扩张等作用。但是,目前黄酮类药物仍存在以下问题:(1)黄酮类化合物结构繁多,生物活性极其广泛,但作用强度普遍较弱;(2)黄酮类化合物水溶性较低,影响药物的吸收与疗效。新型黄酮类化合物的合成仍有一定的意义。     

Synthesis of 5H-[1,3]thiazolo[3,2-a]pyrimidin-5-one derivatives

The reaction of 2-aminothiazoles with ethyl acetoacetate in acetic or polyphosphoric acid gave a series of 5H-[1,3]thiazolo[3,2-a]pyrimidin-5-one derivatives which were nitrated with a mixture of nitric and sulfuric acid to 6-nitro-5H-[1,3]thiazolo[3,2-a]pyrimidin-5-ones, and the latter were reduced to the corresponding amines.     

Synthesis of some 7-substituted thiazolino [3,2-a] benzimidazoles

The 7-amino (IV) and 7-acetamido (I) derivatives of thiazolino[3,2-a]benzimidazole were synthesized. The IR spectra of I, its deutero derivative, and a number of intermediates were studied.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 177–179, February, 1972.     

1H-pyrido[3,2-b]indoles. Synthesis and investigation of some their spectroscopic and chemical properties

At boiling in trifluoroacetic acid derivatives of 3-cyanovinyl-3-p-nitrophenylaminoindole are cyclized into the corresponding pyrido[3,2-b]indoles as a results of activation of the CN group. Thermal cyclization of ethyl indolylacrylate occurs with participation of the more reactive ethoxycarbonyl group to give 3-cyanopyrido[3,2-b]indole.RF State Scientific Center NIOPIK, Moscow 103787, Russia. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 362–367, March, 2000.     

Condensed Pyridazines. Part I. Synthesis of 2-Oxo-2H-pyrano[2,3-D]-pyridazine and 2-Oxo-2H-pyrano[2,3-c] pyridazine

The reaction of 4,7-diehlorofuro[2,3-d]pyridazine (1) with potassium cyanide in DMSO gave two products, (E)-3,6-diehloro-5-(2-cyanovinyl)-4-hydroxypyridazine (II) and 5,8-dichloro-2-oxo-2H-pyrano[2,3-d]pyridazine (III) as a result of ring opening or ring expansion. A new ring system, 2-oxo-2H-pyrano[2,3-c]pyridazines (IX, XII, XIII) was obtained from 5,8-dichloro-3-methyl-2-oxo-2H-pyrano[2,3-d]pyridazine (VI).     

Synthesis of 2H-pyrano[2,3-d]pyrimidine derivatives

Two series of 2H-pyrano[2,3-d]pyrimidine-2,5(6H)-dione derivatives have been prepared. Thus, the reaction of 6-hydroxy-pyrimidin-4(3H)-ones (1 a–c) with bis-2,4,6-trichlorphenyl malonates (2 a–d) or diethyl malonates (3 a–d) afforded good yields of 4-hydroxy-2H-pyrano[2,3-d]pyrimidine-2,5(6H)-diones (4 a-l). Application of our modifiedPechmann reaction^9–11 using -aminocrotonate (5) or -keto esters (6, 7) in the presence of ammonium acetate yielded the 2H-pyrano[2,3-d]pyrimidinediones8 a–h.Dedicated to Prof. Dr.Karl Schlögl, University of Vienna, on the occasion of his 60th birthday.     

Polymethine dyes — Furo[3,2-f]quinol-7-yl and furo[3,2-f]quinol-9-yl derivatives

New heterocyclic bases — 7- and 9-methylfuro[3,2-f]quinolines — were synthesized by condensation of 5-aminobenzofuran double tin hydrochloride salt with paraldehyde in dilute hydrochloric acid and with methyl vinyl ketone in ethanol in the presence of ferric chloride and zinc chloride. Polymethine dyes of various types were obtained from the quaternary salts of the synthesized bases. The introduction of a furan ring in the 5,6 position of quino-2- and quino-4-carbocyanines gives rise to a smaller bathochromic effect than the analogous introduction of a thieno and, particularly, a benzo group.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 391–394, March, 1977.     

Synthesis of 7-formyl-2-methyl-4-oxo-3,4-dihydropyrrolo[3,2-d]-pyrimidine and some other 7-substituted derivatives

A method that utilizes the Vilsmeier reaction to form a pyrrole ring was developed for the preparation of the previously unknown 7-formyl-2-methyl-4-oxo-3,4-dihydropyrrolo[3,2-d]pyrimidine from 2,6-dimethyl-5-amino-4-oxo-3,4-dihydropyrimidine. The nitrile, which was converted to the amide, was obtained from the oxime of the synthesized aldehyde. 7-Unsubstituted pyrrolopyrimidine was synthesized by oxidation of the aldehyde to the corresponding acid and subsequent decarboxylation. The IR and PMR spectroscopic data are presented.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1672–1674, December, 1977.     

Highly regioselective synthesis of 7-oxo-7H-[1,3,4]thiadiazolo[3,2-a]pyrimidine-5-carboxylate derivatives under mild conditions

7-Oxo-7H-[1,3,4]thiadiazolo[3,2-a]pyrimidine-5-carboxylate derivatives are biologically and pharmacologically useful heterocycles. An efficient synthetic methodology for this class of compounds was developed through catalyst-free, one-pot reactions between 2-aminothiadiazoles and dimethyl acetylenedicarboxylate (DMAD) in THF with the aid of ultrasound irradiation. The reactions show applicability to a wide range of substrates and high regioselectivity for the “7-one” products over their “5-one” isomers. Detailed reaction mechanisms were mapped out by theoretical modeling analysis based on density functional theory (DFT) calculations. Mechanistic studies indicate that the favored reaction pathway involves a sequence of hydrogen-bond directed Michael addition, synergistic proton transfer/five-membered ring opening, and intramolecular cyano hetero-Diels-Alder reactions.     

Condensed Pyridopyrimidines. 7. Synthesis of Condensed Triazolo[4,3-c]- and Tetrazolo[1,5-c]pyrimidines

Novel dihydro-5H-pyrano[3',4':5',6']pyrido[2,3-d]-1,2,4-triazolo[4,3-c]pyrimidines and 1,2,3,4-tetrazolo[1,5-c]pyrimidines have been synthesized from 2-amino-3-cyano-7,7-dimethyl-7,8-dihydro-5H-pyrano[4,3-b]pyridine.     

Synthesis and reactions of some derivatives of 1,2-dihydrothiazolo [3,2-a]pyridinium salts

The condensation of 2-mercaptopyridine, 2-mercapto-4-methylpyridine, and 2-mercapto-6-methylpyridine with -bromoacetaldehyde and its diethyl acetal has given cyclic products (3-hydroxy- and 3-ethoxy-2,3-thiazolo[3,2-a]pyridinium salts), from which cyanine dyes have been synthesized.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1254–1257, September, 1973.     

Synthesis of pyrrolo[3,2-b]indole derivatives

The reaction of N-acetylindoxyl hydrazone with ketones in alcohol gave N-acetylindoxyl alkylindenehydrazones, which were converted to pyrrolo[3,2-b]indole derivatives by treatment with glacial acetic acid. Pyrrolo[3,2-b]indole derivatives were also obtained in the reaction of N-acetylindoxyl hydrazone with ketones in glacial acetic acid. The structures of the synthesized products were confirmed by data from the IR, UV, PMR, and mass spectra.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 201–205, February, 1982.     

Synthesis of derivatives of a new heterocyclic system, 9-oxo-1,3,4-thiadiazolo[3,2-a]pyrido[3,2-e]pyrimidine

Reaction of 2-substituted 5-imino-7-oxo-1,3,4-thiadiazolo[3,2-a]pyrimidines with pentane-2,4-dione in polyphosphoric acid yields 9-oxo-1,3,4-thiadiazolo[3,2-a]pyrido[3,2-e]pyrimidines.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2037–2038, October, 1995.The authors are grateful to V. A. Dorokhov for the skilled preparation of the paper for publication.