Palladium catalyzed synthesis of the furanoterpene ircinin-4

A flexible entry into 2,4-disubstituted furan derivatives is outlined emplo ying sulfonium salt 1 as a well accessible starting material. Condensation of the sulfur ylide derived from 1 with aldehydes, palladium catalyzed open ing of the vinyloxirane thus formed, and a final oxidative cyclization of t he furan ring constitute the key steps of this method. Its utility is exemp lified by the first total synthesis of the marine natural product ircinin-4 (2).