New Reagents for the Regiospecific Synthesis of Naturally Occurring Quinizarins

Article abstract of DOI:10.1021/jo00225a102

A modified Nef reaction applied to 4-nitrobutanoates gives the corresponding acetals which after hydrolysis and enol silylation yield the new 1,3-dienes 1-methoxy-1,4-bis(trimethylsiloxy)butadiene and its 3-methyl derivative.The latter reacts smoothly with chloronaphthoquinones and provides simple and efficient syntheses of 2-methylquinizarin, islandicin, digitopurpone, and erythroglaucin.