Synthetic study of piericidins. I. Synthesis of the side chain of piericidin B1

The side chain of piericidin B1 having four (E)-olefinic linkages was prepared. The coupling reaction of the non-conjugated aldehyde (22) derived from 4, 4-dimethoxy-2-butanone and the sulfone (13) afforded a diastereomeric mixture of the hydroxy sulfone (27). Benzoylation of 27 followed by reductive olefin formation with sodium amalgam gave the desired all-trans-tetraene (29) possessing an (E)-C(5)-C(6) double bond, which was transformed to the alcohol (1) corresponding to the side chain of piericidin B1.