Palladium catalyzed reactions of 2-EN-4-YNE carbonates with organoboronic acids

Abstract

Recently, transition metal catalyzed carbon-carbon bond formation reactions gain numerous importance in organic chemistry. Especially, palladium catalyzed carbon-carbon bond formation reactions provide lots of advantages in organic synthesis. For instance, palladium catalyst is extensively used in many allene formation reactions of various substrates such as propargyl and enyne compounds. This thesis describes the preparation of E-configured aryl or alkenyl functionalized vinylallene structures via the reaction of a 2-en-4-yne carbonates with organoboronic acids in the presence of Pd (0) precursor. This method, which proceeds through formation of s-vinylallenylpalladium intermediate, is applicable for both (E)- and (Z)- configured enyne carbonates and appeared to have wider scope for both organoboronic acids and enyne substrates. The reaction of the carbonate of an enantiomerically enriched enynol reagent with phenylboronic acid under the optimal conditions was proceeded and center-to-axis chirality transfer selectivity was investigated. Complete racemization was observed.