Scheme 3From: Utility of 2-thioxo-pyrido[2,3-d]pyrimidinone in synthesis of pyridopyrimido[2,1-b][1,3,5]-thiadiazinones and pyridopyrimido[2,1-b][1,3]thiazinones as antimicrobial agentsSynthesis of pyridopyrimidine derivatives (17a–c), (19), (21) and (23)Back to article page