Abstract
Two piericidin analogues having a simple aromatic ring were synthesized based on a palladium-catalyzed cross-coupling reaction and the reaction of sulfone and aldehyde by the Julia coupling procedure. The reaction of 3-methoxyphenyl-tri-n-butyltin (8) and a mixture of allylic chlorides ((E)-9 and (Z)-10) in the presence of tetrakis(triphenylphosphine) palladium(0) afforded a mixture of 5-arylacetals (E)-11 and (Z)-12. The coupling reaction of the non-conjugated aldehyde (E)-13 or (Z)-14 prepared from the 5-arylacetal (E)-11 or (Z)-12 and the sulfone 4 provided (2E)-19 or (2Z)-20. Benzoylation of (2E)-19 or (2Z)-20 followed by reductive olefin-formation with sodium amalgam gave the piericidin analogue (2E)-1 or (2Z)-2. Analogue (2E)-1 has the same side chain as natural piericidin and analogue 2 is the (2Z)-isomer of analogue 1 at the side chain.
