Switching Selectivity in Borylative Allyl-Allyl Cross-Coupling through Synergistic Catalysis.

A Cu/Pd-catalyzed borylative coupling of allenes with allyl carbonates is reported. Synergistic Cu/Pd catalysis enables a divergent selectivity compared to Cu catalysis and allows for the regio-, diastereo-, and enantioselective formation of synthetically versatile chiral borylated 1,5-dienes featuring two adjacent tertiary stereocenters. DFT calculations support a closed inner-sphere S2' transmetalation between the catalytic allyl copper and allyl palladium intermediates and point at the reductive elimination of the resulting bis(allyl)Pd intermediate as the regio- and diastereo-determining step.

Bifunctional Skipped Dienes through Cu/Pd-Catalyzed Allylboration of Alkynes with Bpin and Vinyl Epoxides.

A method for the use of vinyl epoxides in catalytic allylboration of alkynes is described. This transformation allows for the synthesis of bifunctional skipped dienes bearing both an allylic alcohol and an alkenylboronate from simple starting materials with high regio- and stereoselectivity. These two functionalities provide these products with highly versatile reactivity, as shown by their stereocontrolled conversion into cyclic boron compounds and polyenes.

Copper-catalyzed -alkenylation of phosphonates.

Copper catalysis allows the direct oxygen alkenylation of dialkyl phosphonates with alkenyl(aryl)iodonium salts with selective transfer of the alkenyl group. This novel methodology proceeds with a wide range of phosphonates under mild conditions and gives straightforward access to valuable enol phosphonates in very good yields.