Enantioselective Intermolecular [2+2+2] Cycloadditions of Ene-Allenes with Allenoates

An enantioselective [2 + 2 + 2] cycloaddition of ene-allenes with allenoates is described, which transforms simple pi-components into stereochemically complex carbocycles in a single step. The rhodium(I)-catalyzed cycloaddition proceeds with good levels of enantioselectivity, and with high levels of regio-, chemo-, and diastereoselectivity. Our results are consistent with a mechanism involving an enantioselective intermolecular allene-allene oxidative coupling.