Stereospecific Pd(0)-catalyzed arylation of an allylic hydroxy phosphonate derivative: formal synthesis of (S)-(+)-ar-turmerone.

Reaction of the (1S)-allylic hydroxy phosphonate 1(S) with methyl chloroformate in pyridine yields the corresponding carbonate 3(S). The carbonate 3(S) undergoes a palladium-catalyzed arylation with p-tolyl tributylstannane to give both the 1E and 1Z vinyl phosphonates 6 (85:15). The E and Z vinyl phosphonates 6 were shown to have the opposite configuration at C-3. The major vinyl phosphonate isomer (3S,1E), was converted to (3S)-3-(p-tolyl)-butanal 8(S), completing a formal total synthesis of (S)-ar-turmerone 5a.