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 ] pyrimidinecar bonitriles

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‐oxopyrrolo[1,2‐ a ]thieno[3,2‐ d ]pyrimidine‐7‐carbonitriles 10 , respectively. The transformation of compounds 4 and 8 to the tricyclic aminonitriles 9 and 10 involves a dimerization step followed by a pyrrole cyclization. The tert ‐butyl ester derivatives 4d and 8d upon treatment with sodium hydride underwent a Thorpe‐Ziegler cyclization to provide enaminoesters of fused 1,3‐thiazines ( 16 and 17 , respectively) as major products.