Stereoselective Tandem Bis-Electrophile Couplings of Diborylmethane.

A copper-catalyzed three-component linchpin coupling method for the stereoselective union of readily available epoxides and allyl electrophiles is disclosed. Transformations employ [B(pin)]2-methane as a conjunctive reagent, resulting in the formation of two C-C bonds at a single carbon center bearing a C(sp3) organoboron functional group. Products are obtained in 42-99% yield, and up to >20:1 dr. The utility of the approach is highlighted by stereospecific transformations entailing allylation, tandem cross coupling, and application to the synthesis 1,3-polyol motifs.