SYNTHESES WITH HETEROCYCLIC BETA-ENAMINONITRILES - AN EXPEDITIOUS SYNTHETIC APPROACH TO POLYFUNCTIONALLY SUBSTITUTED 5-PHENYLSULFONYLTHIOPHENES AND THEIR FUSED DERIVATIVES

Phenylsulfonylacetophenones 1 react with a mixture of elemental sulfur and malononitrile to yield the corresponding o-4-aryl-5-phenylsulfony lthiophene-3-carbonitriles 2. Compound 2a could be annelated to the co rresponding thieno[2,3-d]pyrimidine and thieno[2,3-c]-pyrazole derivat ives 3 and 5 upon reaction with nitrogen nucleophiles (cyanamide and h ydroxylamine hydrochloride), respectively. The applicability and synth etic potency of 5 to develop a facile convenient route to the polyfunc tionally substituted thieno[2',3':3,4]pyrazolo[1,5-a]pyrimidines 8, 14 , 17, 20, and 21 is reported. Chemical and spectroscopic evidences for the structures of the new compounds are presented.