Synthesis of Some New Thiazolo[3,2- a ]pyrido[2,3- d ]pyrimidinones and Isoxazolo[5′,4′:4,5]thiazolo [3,2- a ]pyrido[2,3- d ]pyrimidinone

Abstract

6-Amino-2,3-dihydro-2-thioxo-4(1 H )-pyrimidinone 1 reacts in boiling DMF with a cyclic f , g -unsaturated ketones 2 affording the pyrido [2,3- d ]pyrimidinone 6a , b , the latter compound condensed with aldehyde in presence of chloroacetic acid to yield thiazolo[3,2-a] pyrido [2,3-d]-pyrimidinones ( 7 , 8 ) respectively. The alkylation of pyridopyrimidinone it gave the 2-alkylthio derivatives 10a-e , compound 10b cyclized to thiazolopyridopyrimidinone derivative 13 . Also, the condensation of compounds 7a , b with hydoxylamine gave the corresponding isoxazolo[5',4':4,5]thiazolo[3,2-a]pyrido[2,3-d]pyrimidinone.