Copper‐catalyzed asymmetric 1,4‐conjugate addition of dialkylzinc to enones

Abstract

Asymmetric 1,4-conjugation addition of dialkylzinc (diethylzinc and dimethylzinc) to cyclic enones, chalcone and nitroalkenes was achieved by a 25 mol% (R)-6,6 -Br 2 -BINOL(1f), 25 mol% CuSPh and 100 mol% dicyclohexylmethylamin(Cy 2 NMe) catalyst system. The Cu(I) catalyst system enables the cyclic enone, chalcone and nitroalkene generality with high enantioselectivity (up to 84% ee) and isolated yield (up to 94%) under mild reaction conditions.

Synthesis of (−)-Neothiobinupharidine

“…Instead, the intermediate cyclopentenolates undergo proton exchange with the product ketones and yield diastereo- and regioisomers in addition to doubly allylated products . For instance, methylzinc conjugate additions to cyclopentenone proceed with high levels of enantioselectivity, but allylation of these intermediates is problematic (Table , entries 1, 2, and 3), in line with recent observations by Cook …”