New Regioselective Synthesis of 7H-Imidazo[2,1-b][1,3]thiazine and 2H,6H-Pyrimido[2,1-b][1,3]thiazine Derivatives

Abstract A series of the title compounds were prepared by the reaction of amidines 2 with α-bromoketones, acid chlorides or acrylic dienophiles. The four steps synthesis reaction from thiourea and full characterisation of 7H-imidazo[2,1-B][1,3]thiazines 4, 2H,6H-pyrimido[2,1-B][1,3]thiazin-6-ones 5, and 2H,6H-pyrimido[2,1-B][1,3]thiazines 6 are described.