Novel heterocyclic-fused pyrimidines viz pyrrolo[1,2-c]pyrimidines 4-8, pyrimido[5,4-e]pyrrolo[1,2-c]pyrimidines 9-14, pyrimido[4?,5?:4,5] pyrimido[1,6-a]azepines 16-18, pyrrolo[1?,2?:1,6]pyrimido[4,5-d][1, 3]thiazines ...