Synthesis of Multisubstituted Allenes via Nickel-Catalyzed Cross-Electrophile Coupling

In this context, we report the successful application of a cross-electrophile strategy in the synthesis of multisubstituted allenes. Under the catalysis of nickel, reductive cross-coupling between propargyl carbonates and organoiodides provides an entry to prepare tri- or tetrasubstituted allenes without employing any pregenerated organometallics. Furthermore, propargyl carbonates also prove to be suitable allenylating agents in nickel-catalyzed asymmetric reductive aryl-allenylation of aryl-iodide-tethered unactivated alkenes, furnishing a variety of chiral benzene-fused cyclic compounds bearing a quaternary allenyl-substituted stereogenic center in a highly enantioselective manner.