Combining NHC-Cu and Brønsted base catalysis: enantioselective allylic substitution/conjugate additions with alkynylaluminum reagents and stereospecific isomerization of the products to trisubstituted allenes

All-catalytic route to trisubstituted allenes: The first examples of catalytic enantioselective allylic substitution reactions that involve alkyne-based nucleophiles and lead to products having tertiary stereogenic centers are followed by an exceptionally stereospecific amine-catalyzed isomerization to trisubstituted allenes (see picture; NHC = N-heterocyclic carbene).