Synthesis of dienes through phosphine oxide intermediates from aldehydes

Abstract

Mehtyldiphenylphosphine oxide, readily available via hydrolysis of methyldiphenylphosphonium bromide by treatment with n-BuLi, reacted with aldehydes having $\alpha$-hydrogen, acetylchloride, t-BuOK, and various aldehydes as well as ketones to give 1-4-disubstituted 1,3-dienes in good overall yields under mild conditions. However, four isomeric dienes which consist of (Z,Z), (Z,E), (E,Z), and (E,E) were confirmed, and (E,E)-diene exists in major.