Pd-Catalyzed Asymmetric Allylic Substitution Cascade of But-2-ene-1,4-diyl Dimethyl Dicarbonate for the Synthesis of Chiral 2,3-Dihydrofurans.

Herein an efficient Pd-catalyzed asymmetric allylic substitution cascade of both (E)- and (Z)-but-2-ene-1,4-diyl dimethyl dicarbonates with alpha-substituted cyano ketones is described for the preparation of chiral 2,3-dihydrofurans in up to 97% yield with 98% ee. A suggested steric control process has been proposed to illustrate the differences in enantioselectivity between the reactions of (E)- and (Z)-allyl substrates. The cascade reaction could be conducted on a gram-scale, and the resulting product allows for several transformations.