Some methyl substituted benzo[b]naphtho[2,3-d]thiophenes

Seven benzo[b]naphtho[2,3-d]thiophenes have been prepared with methyl groups substituted in the 6,7, and 8-positions. These compounds are structurally related to the sulfur analogs of cholanthrene and methylcholanthrene.     

2,4-Diaryl-2,3-dihydrobenzo[b][1,4]thiazepines

2,4-Diaryl-2,3-dihydrobenzo[b][1,4]thiazepines are obtained in a single stage from chalcones and ortho-aminothiophenol in the presence of triethylamine. The nature of the electronic transitions in their UV absorption spectra is discussed with the use of quantum-chemical methods. It was shown that the seven-membered ring does not invert in the range of temperatures between –80 and +140 °C and is in the boat form. The main initial event in the fragmentation of the molecules of the obtained compounds under electron impact is the formation of benzothiazole-containing radicalions. In an acidic medium 2,4-diphenyl-2,3-dihydrobenzo[b][1,4]thiazepine is hydrolyzed to 3-(2-aminophenylthio)-1,3-diphenyl-1-propanone, and in its reaction with 2,4-dinitrophenylhydrazine chalcone hydrazone and o-aminothiophenol are formed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1638–1642, December, 1983.     

Electrophilic substitution in benzo[b]thieno[2,3-c]pyridine. Acylation

A study has been made of the acetylation and benzoylation of substituted benzo[b]thieno[2, 3-c]pyridines. It has been shown that acetylaton proceeds exclusively at position 8, whereas benzoylation leads to a mixture of products of substitution at positions 6 and 8. The molecules in question have been calculated in the PPP and MNDO approximations.L. M. Litvinenko Institute of Physical Organic Chemistry and Coal-Tar Chemistry, Academy of Sciences of the Ukraine, Donetsk 340114. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 701–705, May, 1994. Original article submitted March 3, 1994.     

Electrophilic substitution in benzo[b]thieno[2,3-c]pyridines. Nitration

A study was carried out on the nitration of substituted benzo[b]thieno[2,3-c]pyridines. Depending on the conditions, either one nitro group is introduced at C₍₆₎ or two nitro groups are introduced at C₍₆₎ and C₍₈₎. If C₍₆₎ is blocked, a mixture of products is formed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 706–709, May, 1993.     

The synthesis of the monomethyl derivatives of benzo[b]naphtho[2,3-d]thiophene

The synthesis of all the monomethyl derivatives of benzo[b]naphtho[2,3-d]thiophene is described.     

A novel practical synthesis of pyrrolo[1,2-a]thieno[2,3-e][1,4]diazepines

In an investigation of new heterocyclic systems, a novel way to obtain pyrrolo[1,2-a]thieno[2,3-e][1,4]diazepine 8 was effected by ring closure to the appropriate nitroaldehyde compound which was synthesized in five steps from 3-bromomethyl-2-nitrothiophene 1 .     

Ring-contraction from benzo[b][1,4]thiazines to benzo[d]thiazolines induced by oxygen

An unexpected ring-contraction from benzo[b]pyrazino[1,2-d][1,4]thiazine-1,4-diones (6) to benzo[4,5]thiazolo[3,2-a]pyrazine-1,4-diones (7) has been developed. The preliminary mechanistic studies showed the transformation contained two independent steps: the first step is the formation of a Michael adduct upon the addition of the protic solvent, in the presence of base, to the C-2-C-3 double bond of compound 6, and the second step is a ring-contraction induced by oxygen via the migration of sulfur atom from C-2 to C-3 position. And its scope is also studied.     

Synthesis and reactivity of furo[2,3-e]pyrrolo[1,2-a][1,4]diazepin-9-one

A convenient method for the synthesis of furo[2,3-e]pyrrolo[1,2-a][1,4]diazepin-9-one is described. It has been C-alkylated with amine (piperidine, morpholine, 4-methylpiperazine) and N-alkylated with alkyl halides (methyl iodide and benzyl chloride).     

Synthesis of anthra[b]thiophenes and benzo[b]naphtho[d]thiophenes

All isomers of the parent anthra[b]thiophenes and benzo[b]naphtho[d]thiophenes, namely anthra[2,3-b]thio-phene, anthra[2,1-b]thiophene, anthra[1,2-b]thiophene, benzo[b]naphtho[2,3-d]thiophene, benzo[b]naphtho[2,1-d]thiophene and benzo[b]naphtho[1,2-d]thiophene were synthesized using a new procedure.     

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.L. M. Litvinenko Institute of Physical Organic Chemistry and Coal Tar Chemistry, National Academy of Sciences of Ukraine, Donetsk 340114. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 694–699, May, 1995. Original article submitted March 22, 1995.     

Synthesis and reactions of benzo[b]furo[2,3-c]pyrylium salts

A method has been developed for the synthesis of 3-acetonyl- and 3-phenacylben-zo[b]furans by cyclization of 1-arloxy-2,4-pentanediones and 1-phenyl-4-aryloxy-1,3-butanediones in polyphosphoric acid. Acylation of 3-acetonyl(phenyl-benzo-[b]furans with aliphatic acid anhydrides in the presence of perchloric acid gives the benzo[b]furo[2,3-c]pyrylium perchlorates. The recyclization of the pyrylium salts with ammonia, aqueous alkali, and morpholine has been examined.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 889–893, July, 1987.     

Synthesis and reactions of benzo[b]thieno[2,3-c]pyrylium pairs

Benzo[b]thieno[2,3-c]pyrylium perchlorates were obtained in high yields in the acylation of benzo[b]thien-3-ylacetone with aliphatic acid anhydrides in the presence of 70% perchloric acid. Treatment of the products with ammonia converts them to benzo[b]thieno[2,3-c]pyridines (in yields higher than 90%), whereas hydroxy and dialkylamino derivatives of dibenzothiophene were obtained in up to 50% yields by treatment of the products with alkalis or secondary amines, respectively.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1351–1354, October, 1981.     

An efficient synthesis of benzo[b]benzofurano[2,3-e]-[1,6]naphthyridine-8-ones

An efficient method for the synthesis of benzo[b]benzofurano[2,3-e][1,6]naphthyridine-8-one derivatives has been developed via Pictet-Spengler reaction of 4-(3-aminobenzofuran-2-yl)quinoline-2-ones,which could be obtained from alkylation of 4-bromomethylquinoline-2-ones with salicylonitrile and subsequent Thorpe-Ziegier isomerization,with aromatic aldehydes under p-TsOH as catalyst in good yields.     

Nitration studies of naphtho[2,3-c][1,2,5]thiadiazole

Nitration of naphtho[2,3-c][1,2,5]thiadiazole gives the 5-nitro derivative in 61–66% yield. Chlorination of this product apparently gives an unstable addition product which loses hydrogen chloride on recrystallization to give 4-chloro-8-nitronaphtho[2,3-c][1,2,5]thiadiazole. Thus, naphtho[2,3-c][1,2,5]thiadiazole under nitrating conditions behaves as a 2-substituted naphthalene rather than as an anthracene analog.     

Synthesis of Benzofuro[3,2-e][1,4]diazepines

A synthesis of 4-N-oxides and of 3-hydroxy derivatives of 1,3-dihydro-2H-benzofuro[3,2-e][1,4]diazepin-2-ones and of 2,3-dihydro-1H-benzofuro[3,2-e][1,4]diazepines is described. Condensation of 2-acetyl- and 2-benzoyl-3-ethoxycarbonylaminobenzofurans with acrylonitrile gave derivatives of 1,2-dihydro- and of 1,2,3,4-tetrahydrobenzofuro[3,2-b]pyridine.