Nickel-Catalyzed Cross-Coupling of Vinyl Dioxanones to Form Enantiomerically Enriched Cyclopropanes

Under the conditions of nickel(0) catalysis, enantio­merically enriched vinyl dioxanones engage boroxines or B2(pin)2 in stereo­specific cross-coupling to form diverse tetrasubstituted cyclopropanes bearing all-carbon quaternary stereo­centers. The collective data corroborate a mechanism involving nickel(0)-mediated benzylic oxidative addition with inversion of stereo­chemistry followed by reversible olefin insertion to form a (cyclopropyl­carbinyl)­nickel complex, which upon reductive elimination releases the cyclopropane.