3, 4??Dihydro??2??phenyl??2H??pyrano [2, 3??b] pyridines. Novel aza analogs of flavans

TM Bargar, T Wilson, JK Daniel

Index: Bargar, T. M.; Wilson, T.; Daniel, J. K. Journal of Heterocyclic Chemistry, 1985 , vol. 22, p. 1583 - 1592

Full Text: HTML

Citation Number: 14

Abstract

Abstract Complementary approaches to the synthesis of the title compounds 1 are described. Metallation of 3, 5-di-bromo-2-methoxypyridine (5b) by bromine/lithium exchange gave selectively the 3-lithio intermediate 6 which was trapped with substituted cinnamaldehydes 7, providing allylic alcohols 8 in good yields. Methyl ether cleavage and concomitant cyclization occurred on exposure to concentrated hydrobromic acid in hot ...