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It is shown that the expansion of the tetrahydropyridine fragment requires the presence of an aryl substituent at position 4 of the tetrahydrothieno[3,2-c]pyridines as it stabilizes the intermediate acyclic zwitterion.

Acylation of 5-(benzothiophen-3-yl)pyrimidine-2,4,6(1H,3H,5H)-trione using acetic and propionic anhydride in the presence of 70% perchloric acid gave the 6-methyl(ethyl)-1,3-dioxo-1,2,3,4-tetra-hydro[1]benzothieno[3',2':4,5]pyrano[2,3-d]pyrimidin-5-ium perchlorates. Hydrolysis of the pyrano[2,3-d]pyrimidin-5-ium salts in aqueous alcohol solution gave 5-(2-acylbenzothiophen-3-yl)-pyrimidine-2,4,6(1H,3H,5H)-triones. Cyclocondensation of the latter with aromatic amine hydrochlorides produced 6-R-5-aryl-1,3-dioxo-1,2,3,4-tetrahydro[1]benzothieno[3',2':4,5]pyrido[2,3-d]-pyrimidin-5-ium chlorides. 6-R-5-Aryl-5,6-dihydro[1]benzothieno[3',2':4,5]pyrido[2,3-d]pyrimidine-1,3(2H,4H)-diones were synthesized by reduction of the pyrimidinium chlorides using sodium borohydride.

The reagent system DMF—Tips-Cl is used in a Pictet—Spengler reaction leading to title compounds (III).

A new strategy for the synthesis of the eight-membered heterocyclic skeleton of tetrahydro-quinazolino[3,2-c][2,3]benzodiazocin-15-ones, based on the Pictet–Spengler reaction of 3-amino-2-[2-(3,4-dimethoxyphenyl)ethyl]quinazolin-4(3H)-one with carbonyl compounds in acidic media, is proposed.

A series of new 3-substituted 6-(4-chlorophenyl)-9-methyl-12H-[1]benzofuro[3,2-e][1,2,4]triazolo[4,3-b][1,2]diazepines was synthesized from the corresponding bicyclic 1-(4-chlorophenyl)-3,5-dihydro-8-methyl-4H-[1]benzofuro[2,3-d][1,2]diazepin-4-one. The synthesis strategy makes use of silylation–amination as the key step, allowing a wide range of derivatives to be prepared. .

It has previously been shown that 5-o-chlorobenzyltetrahydrothieno[3,2-c]pyridines react with alkynes only in alcohols to form the products of cleavage of the tetrahydropyridine ring and involving molecules of the solvent and the products of debenzylation (N-vinyltetrahydrothienopyridines) [1]. 2-Trifluoroacetamidotetrahydrothieno[2,3-c]pyridines react readily with alkynes both in methanol and in acetonitrile to give a high yield of tetrahydrothieno[3,2-d]azocines [2]. 2-Acetamido-substituted thienopyridines react with alkynes in acetonitrile at 20oC to give modest yields (30-59%) of the thienoazocines. There occur in methanol simul-taneous processes of expansion and cleavage of the tetrahydropyridine fragment to form a mixture of the acetamido-substituted tetrahydrothieno[3,2-d]azocines and 2-acetamido-3-ethoxycarbonyl-4-(N-vinyl-N-R)aminoethyl-5-methoxymethylthiophenes [2]. Continuing our study of the dependence of the transformation of tetrahydrothienopyridines with activated alkynes we have shown, for the first time, that the tetrahydrobenzothieno[2,3-c]pyridines 1, 2 react with acetylene dicarboxylic ester (ADCE) in acetonitrile to form the spiro[benzothiophene-3,4'-pyridines] 3, 4 in 20-35% yields.

The reaction of 1,7-dimethyl-3(2H)-benzo[b]furo[2,3-c]pyridone with phosphoric acid amides gave 1,7-dimethyl-3-dimethylamino (morpholino)benzo[b]furo[2,3-c]pyridines. A method for the synthesis of 3-amino derivatives of 4-nitrobenzo[b]furo[2,3-c]pyridines, which consists in heating 1,7-dimethyl-4-nitro-3(2H)-benzo[b]furo[2,3-c]pyridone with hexamethyldisilazane and secondary or primary amines in pyridine, was developed.

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.

The heterocyclization of 2-acetyl-3-indolylacetic acid hydrazones and its amides, in contrast to similar derivatives of phenylacetic acid, does not lead to 2,3-dihydro-2-oxo-5-R1-1H-[1,2]diazepino-[4,5-b]indoles but rather to 2-aminoindolo[2,3-c]pyridin-3(2H)-one or azines of 2-acetyl-3-indolyl-acetic acid. 2,3-Dihydro-2-oxo-5-R1-1H-[1,2]diazepino[4,5-b]indoles were obtained by the reaction of 1-alkylaminoacetylindolo[2,3-c]pyrilium perchlorates and of methyl esters of 2-acetyl- and 2-propionyl-3-indolylacetic acid with hydrazine hydrate.