Palladium(II)-Catalyzed Dehydroboration via Generation of Boron Enolates.

The PdII -catalyzed dehydroboration of boron enolates generated from ketones and 9-iodo-9-borabicyclo[3.3.1]nonane was achieved, providing a synthetically versatile protocol from ketones to α,β-unsaturated ketones. The PdII compound employed in this reaction worked catalytically in the presence of Cu(OAc)2 . The high trans-selectivity of the olefinic moiety was observed. Aryl halide moieties (-Br and -Cl) remained intact for this reaction in spite of the presence of a Pd species. An ester substrate could also be applied when a stoichiometric amount of PdII was used. The crossover reactions using boron and silyl enolates revealed that the oxidation reaction is much faster than the Saegusa-Ito reaction.