Chemoselective construction of substituted conjugated dienes using an olefin cross-metathesis protocol

Various substituted conjugated dienes have been made by olefin cross-metathesis. Using either electronic or steric protection,'' one of the olefins of the conjugated diene was deactivated relative to the other for cross-metathesis. The reactions proceed with very high chemoselectivity and, when steric deactivation is used, very high diastereoselectivity.