S. V. Tolkunov

Anomalous Beckmann Reaction of 4-Aryl-2,7,7-trimethyl-5-oxo-5,6,7,8-tetrahydroquinoline Oximes in Polyphosphoric Acid. 1. New Synthesis of 1-Ethoxycarbonyl-2,5,5-trimethyl-5,6-dihydro-4H-pyrido[2,3,4-k,l]acridines

Transformations of oximes of 4-aryl-2,7,7-trimethyl-5-oxo-5,6,7,8-tetrahydroquinolines in PPA have been studied. It is shown that the reaction, depending on substituent at position 4 of quinoline ring, can occur in three directions: aromatization of the saturated ring (Semmler-Wolff aromatization), formation of azepinones - normal products of Beckmann rearrangement, and formation of pyridoacridines.

Acylation and Cyclodehydration of Benzofuran-, Benzothiophene-, and Indolyl-3-acetic Acid Arylamides. Synthesis of Novel Benzofuro[2,3-c]-, Benzothieno[2,3-c], and Indolo[2,3-c]pyrilium and Pyridine Derivatives

The acylation of benzo[b]furan-, benzo[b]thiophene, and indolyl-3-acetic acid arylamides using acetic anhydride in the presence of 70% perchloric acid occurs at the α-position of the heterocycle to give 2-acetylbenzo[b]furan-, 2-acetylbenzo[b]thiophene, and 2-acetylindolyl-3-acetic acid arylamides. Depending on the amount of perchloric used in the reaction they undergo cyclodehydration to 3-arylamino-1-methylhetero[2,3-c]pyrilium salts and to N-aryl-1-methyl-3(2H)hetero[2,3-c]pyridones.

Interaction of benzothieno[2,3-c]pyrylium salts with hydrazine. Derivatives of 5H-[2,3]benzothieno[2,3-e]diazepines

A study has been made of the reaction of 1,3-disubstituted bezothieno[2,3-c]pyrylium salts with hydrazine. It has been shown that 1,3-dialkyl-substituted benzothieno[2,3-c]pyrylium salts interact with hydrazine to give N-amino-1,3-dialkylbenzothieno[2,3-c]pyridines. The presence of a pyrylium ring on one of the positions of the phenyl group leads to a mixture of N-amino derivatives and 5H-[2,3]benzothieno[2,3-e]diazepines. In contrast, 1,3-diphenylbenzothieno[2,3-c]pyrylium perchlorate gives exclusively 5H-[2,3]benzothieno[2,3-e]diazepine.

CONDENSED PYRIDINE BASES SYNTHESIS OF SOME BENZO(b)FURO(2,3-c)-, BENZO(b)- THIENO(2,3-c)-, AND BENZO(b) SELENOPHENO(2,3-c)-QUINOLINES

SummaryCondensation of benzo[b]furan-3(2H-one, benzo[b]thiophen-3(2H)-one and benzo[b]selenophen-3(2H)-one with dimedone gives 2-(3-heteryl)dimedones. Acylation of the latter leads to the corresponding tetracyclic pyrylium salts, from which condensed quinolines are obtained. Some condensed quinoline derivatives are obtained by reaction of 1-oxo-1,2,3,4-tetrahydroheterene[2,3-c]quinolines with sodium borohydride, hydrazine, and hydroxylamine.

Condensed pyridine bases. Reactions of 1-oxo-3,3,6-trimethyl-1,2,3,4-tetrahydrobenzo[b]furo-, benzo[b]thieno-, and indolo[2,3-c]quinolines with electrophilic reagents

A study has been made of thenitrationand bromination of 1-oxo-3,3,6-trimethyl-1,2,3,4-tetrahydrobenzo[bjfuro-, benzo[b]thieno-, and indolo[2,3-c]quinolines. It has been shown that the nitration is directed to the benzene ring (position 10). Bromination by molecular bromine takes place at the 6-CH3 group of the pyridine fragment and yields a mixture of the corresponding nwnobromomethyl and dibromomethyl derivatives, whereas a dimethylacetamide-bromine complex bronzinates the methylene group in position 2, forming the α-bromoketone. The Schmidt reaction of 1-oxo-3,3,6-trimetliyl-1,2,3,4-tetrahydrobenzo[b]furo-, benzol[b]thieno-, and indolo[2,3-c]quinolines have been investigated, as well as conversions of their oximes under conditions of the Beckmann rearrangement.

Condensed pyridine bases. synthesis and reactions of benzofuro[2,3-c]indeno[2,1-e]-, benzothieno[2,3-c]indeno[2,1-e]-, benzofuro-[3,2-c]indeno[2,1-e]-and thieno[2,3:4',5']-thieno[3,2-c]indeno[2,1-e]pyridines

Condensation of hetarene carboxaldehydes with phthalide gave 2-(3-hydroxy-1-oxoinden-2-yl)benzo[b]furan and 2-(3-hydroxy-1-oxoinden-2-yl)-5-ethylthieno[2,3-b]thiophene. Starting from hetaryl acetic acids gave 3-(3-hydroxy-1-oxoinden-2-yl)benzo[b]furan and 3-(3-hydroxy-1-oxoinden-2-yl)benzo[b]thiophene. Acylation of 3-hydroxy-1-oxoinden-2-yl-substituted heterocycles using acetic anhydride in the presence of 70% HClO4 leads to the formation of pentacyclic pyrilium salts. Pentacyclic indenopyridines are prepared by treating the pyrilium salts with ammonia. The reaction of the carbonyl group in the indenopyridines with hydroxylamine, hydrazine hydrate, and in reduction using NaBH4 has been studied.

Electrophilic substitution in benzo[b]thieno- and benzo[b]furo[2,3-c]pyridines. Use of the nuclear overhauser effect for determination of substitution position

The site of electrophilic substitution in benzo[b]thieno- and benzo[b]furo[2,3-c]pyridines has been determined using the nuclear Overhauser effect and by a method based on the difference in reactivity of the isomeric products.

Synthesis of fused tetracycles from the nitration products of benzo[b]thieno[2,3-c]pyridines

The nitration products of benzo[b]thieno[2,3-c]pyridines were used in the synthesis of new fused tetracyclic heterocyclic systems, which are structural analogs of natural ellipticine and olivicine alkaloids. Closure of the pyridine ring gives products only with linear ring fusion. This behavior was explained using the steric strain-stability principle and complete optimization of the structure of these products with a PCMODEL program and MMX force field in conjunction with the π-electron approximation.

Condensed pyridine bases. Electrophilic substitution in 1,7-dimethyl-3(2H)-benzo[b]furo[2,3-c]pyridone

Nitration, bromination, thiocyanation, and acylation of 1, 7-dimethyl-3(2H)-benzo[b]furo[2, 3-c]pyridone were investigated. It was shown that either the 4-nitro- or the 4,6-dinitro derivative is formed as a function of the nitration conditions. Bromination with bromine and thiocyanation with dithiocyanogen yields a bromo derivative at position 4. The product of substitution at the C(6), atom is obtained in acylation with acetyl chloride, and the product of substitution at atoms C(4) and C(6) is obtained with benzoyl chloride. The results of the calculations were generalized in the MNDO approximation.

Electrophilic substitution in benzo[b]furo[2,3-c]pyridines: nitration, acylation

It has been shown that the nitration and acylation of substituted benzo[b]furo[2,3-c]pyridines proceeds exclusively at position 6 of the benzene ring. If position 6 is blocked by a substitutnt, the product of monosubstitution at the C(8) atom is formed. The molecules that were investigated have been calculated in the MNDO approximation.