Fig. 1. Stereodivergent synthesis via dual catalysis.
a Representative stereodivergent synthesis via cooperative catalysis, chiral catalyst (Cat*). b NHC/transition metal cooperatively catalyzed enantioselective annulation reactions, substrate (sub). c Asymmetric propargylic substitution reactions mediated by chiral Cu-allenylidene complexes. d This work: the first stereodivergent propargylation of enals via cooperative NHC/copper catalysis, leading to all four stereoisomers with excellent optical purity.