Abstract
The approach to synthetic studies of diterpenoid acid salmantic acid (34) relied on a modified Robinson annulation process followed by a reductive alkylation, which would facilitates the preparation of a,a-disubstituted b,r unsaturated ketone in a completely regioselective manner. 2. A highly efficient methylenecyclopentane annulation process has been developed based on the Pd(II)-mediated oxidative cyclization of w-unsaturated a-cyano ketones, readily accessed via the Michael addition of 3-butenylmagnesium bromide with 2-cyano-2-cyclo alkenones.