Simple and Efficient Synthesis of Novel Fused Bicyclic HeterocyclesPyrimido-Thiazine and Their Derivatives

摘要

We report simple and efficient synthesis of novel fused bicyclic heterocyclic compounds 3 using bis (methylthio)methylene malononitrile 1 and thiourea 2 with potassium carbonate in DMF at reflux condition. The molar ratios ofthese substrates are 2:1 for the preparation of 2,6-dihydro-2,6-diimino-4,8-bis(methylthio) pyrimido[2,1-b][1,3]thiazine-3,7-dicarbonitrile. This newly synthesized pyrimido thiazine acts as bis-electrophilic species reacting with various nucleophiles yielding 2,6-dihydro-2,6-diimino-4,8-(disubstituted)-pyrimido[2,1-b][1,3]thiazine-3,7-dicarbonitrile in goodyields.