摘要:
Reformatsky reactions of ethyl a-bromopropionate, methyl a-bromobutyrate, and methyl alpha-bromoisobutyrate with N-substituted 6-bromo-2-oxochromene-3-carboxamides in the system diethyl ether-benzene-HMPA give N-benzyl-6-bromo-4-(1-alkoxycarbonylalkyl)-2-oxochroman-3-carboxamides, while in the system diethyl ether-benzene-HMPA-THF, 3-R-1-1-R-2-1-R-3-9-bromo-2,3,4,4a,5,10b-hexahydro-1H-chromeno[3,4-c]pyridine-2,4,5-triones are obtained.