Palladium-catalyzed regioselective domino cyclization of cyclohexadienones.

A mild and efficient Pd-catalyzed arylative domino carbocyclization of cyclohexadienone-containing 1,6-enynes is described. The reaction tolerates a variety of functionalized boronic acids to afford a cis-fused bicyclic framework containing an α,ß-unsaturated ketone with excellent regio- and diastereoselectivity in good yields. The tandem process proceeds with ß-arylation of propargylic ether followed by conjugate addition of a vinyl palladium intermediate and subsequent protonolysis of a palladium enolate.

α-Hydroxyallylsilanes as propionaldehyde enolate equivalents and their use toward iterative aldol reactions.

Smooth and efficient reaction conditions have been found for the transformation of protected ß-hydroxyacylsilanes into the corresponding aldehydes. This opens a new route to iterative aldol reactions, and it has been used for the synthesis of fragments of several bioactive natural products.