PALLADIUM-CATALYZED CYCLIZATION REACTIONS. UNICQUE SYNTHESIS OF CONDENSED THIAZOLES

Article abstract of DOI:10.1016/S0040-4020(01)87432-9

The facile synthesis of 3-methylene-2,3-dihydro-5H-thiazolo<3,2-c>pyrimidin-5-ones (9) has been performed by the catalytic action of a Pd(II) salt on 4-propargylthiopyrimidin-2(1H)-ones (6).Similar Pd(II)-catalyzed cyclization of 3-propargylthio-1,2,4-triazin-5(2H)-ones (10) gives 6-methylene-6,7-dihydro-4H-thiazolo<2,3-c><1,2,4>triazin-4-ones (11) as a main product. 3-methylene-2,3-dihydro-7H-thiazolo<3,2-b><1,2,4>triazin-7-ones (12), the regioisomers of 11, are provided by a base-catalyzed cyclization of 10.