Synthesis of some 7-methyl-3-(2-oxo-2H-chromen-3-yl)- 5H[1,3]thiazolo[3,2-a]-pyrimidin-5-ones

759-763Reaction of 3-(2-amino-4-thiazolyl)coumarins with ethyl acetoacetate in a mixture of PPA and POCl₃ give 7-methyl-3-(2-oxo-2H-chromen-3-yl)- 5H-thiazolo[3,2-a]pyrimidin-5-ones in a single step. Alternatively condensation of 3-(2-amino-4-thiazolyl)coumarins 1 with acetoacetic ester (EAA) 2 results in the formation of Schiff bases 3a-g. These on further reaction with polyphosphoric acid (PPA) and phosphorus oxychloride (POCl₃) give corresponding cyclised compounds. 7-methyl-3-(2-oxo-2H-chromen-3-yl)- 5H[1,3]thiazolo[3,2-a]pyrimidin-5-ones 4a-g. The structures of newly prepared compounds have been confirmed from analytical and spectral data