Oxidative Coupling of Lignans. IV. Monophenolic Oxidative Coupling

Abstract

Oxidative coupling of the monophenolic monoester (6) gives an aryltetralin (12) which is a potential intermediate for the synthesis of clinically active monophenolic lignan lactones. In contrast, oxidative couplings of the monophenols (32) and (35), derived from matairesinol (29), give mixtures of diastereoisomeric cyclooctadiene lignans while 4′-demethyldeoxypodorhizon (26) does not cyclize . These results show that the degree of aromatic substitution in monophenolic

diarylbutanes plays an important role in determining the outcome of oxidative coupling. An alternative synthesis of the lactone (57) from piperonal has been investigated.