A new dimerization reaction producing 2-amino-9-oxopyrrolo[2,1-b)quinazoline-1-carbonitriles and analogous pyrrolo[1,2-a]thieno[3,2-d]pyrimidinecarbonitriles

A series of 2-alkylthio-4-oxo-3-quinazolineacetonitriles 4 and 2-alkylthio- 4-oxothieno[3,2-d]pyrimidine-3-acetonitriles 8 was prepared. Upon treatment with sodium hydride, compounds 4 and 8 react to give 2-amino-4,9-dihydro-9 -oxopyrrolo[2,1-b]quinazoline-1-carbonitriles 9 and 6-amino-4,9-dihydro-9-o xopyrrolo [1,2-a]thieno[3,2-d]pyrimidine-7-carbonitriles 10, respectively. The transformation of compounds 4 and 8 to the tricyclic aminonitriles 9 an d 10 involves a dimerization step followed by a pyrrole cyclization. The te rt-butyl ester derivatives 4d and 8d upon treatment with sodium hydride und erwent a Thorpe-Ziegler cyclization to provide enaminoesters of fused 1,3-t hiazines (16 and 17, respectively) as major products.