Synthesis of novel 1,4-, 3,4-, and 4,5-dihydropyrimidines: First successful POCl 3 chlorination and regioselective alkoxycarbonylation

Abstract

Chlorination of 5,6-dihydropyrimidine-4-(3H)-one derivatives (1) with POCl 3 gave 1,4(3,4)-dihydropyrimidines (3), whose alkoxycarbonylation (ClCOOREt 3N or NaH) afforded regioselectively novel compounds (4). A new Pummerer type rearrangement of compound (1, X p S(O)CH 3) with POCl 3, gave compound (5h).