Copper(I)-Catalyzed Regioselective Asymmetric Addition of 1,4-Pentadiene to Ketones

Abstract

By using commercially available 1,4-pentadiene as a pronucleophile, a copper(I)-catalyzed regioselective asymmetric allylation of ketones is achieved. A variety of chiral tertiary alcohols bearing a terminal (Z)-1,3-diene unit are generated in high (Z)/(E) ratio and high enantioselectivity. Both aromatic ketones and aliphatic ketones serve as suitable substrates. Furthermore, the reactions with (E)-C1(alkyl)-1,4-dienes proceed in moderate yields with acceptable enantioselectivity but with low (Z,E)/others ratio, which demonstrates the partial isomerization of (E)-allylcopper(I) species to (Z)-allylcopper(I) species through 1,3-migration. Subsequent Heck reaction and olefin metathesis compensate for the low efficiency with C1-1,4-dienes. The synthetic utility of the product is further demonstrated by a copper(I)-catalyzed regioselective borylation of the 1,3-diene group.