Reactions of 2-amino-4,5,6,7-tetrahydro[1]benzothiophene-3-carbonitrile and 6-amino-1,4-dihydro-3-methyl-1,4-diphenylpyrano[2,3-c]pyrazole-5-carbonitrile with substituted benzylidenemalononitriles, α,β-acetylenic esters and ketones

Abstract

Reactions of 2-amino-4,5,6,7-tetrahydro[1]benzothiophene-3-carbonitrile (1a) with substituted benzylidenemalononitriles gave 4-amino-2-(1-cyano-2-arylvinyl)benzothieno[2,3- d]pyrimidine derivatives (3) as ( E,Z)-mixtures and in one case (2c) as separated ( Z)- and ( E)-isomers. Similar treatment of 6-amino-1,4-dihydro-3-methyl-1,4-diphenyl-pyrano[2,3- c]pyrazole-5-carbonitrile (4) yielded similarly-formed pyrazolopyranopyrimidine derivatives (5a, b) as ( Z)-and ( E)-stereoisomers. Attempted acetylation of the aminobenzothienopyrimidines resulted in degradation of the pyrimidine ring and the formation of N-(3-cyano-4,5,6,7-tetrahydro[1]benzothien-2-yl)acetamide (1b). Treatment of 4 with acetylenic esters and ketones (6a-d) afforded the ( Z)-substituted enaminopyrano[2,3- c]pyrazole derivatives. Reacting 1a with aroyl phenyl acetylenes gave by Michael addition the enamino-ketones (8a-c).