Enantioselective Alkynylation of Pyrazole-4,5-diones with Terminal Alkynes Catalyzed by Copper/PyBisulidine

J Org Chem. 2023 Oct 6;88(19):13645-13654. doi: 10.1021/acs.joc.3c01338. Epub 2023 Sep 8.

Abstract

A copper/PyBisulidine-catalyzed enantioselective alkynylation of electrophilic pyrazole-4,5-dione with terminal alkynes has been developed. Chiral tertiary propargylic alcohols bearing the pyrazolone motif were prepared with yields (up to 99%) and enantioselectivities (up to 99% ee). The prominent feature of this protocol includes its mild reaction conditions and good stereoselectivities. The nonlinear effect study showed that the catalytically active specie was a monomeric catalyst and that the excess copper activated the alkynes through the π-system.