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

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.

High diastereo- and enantioselective Michael addition of 3-acetoxy-2-oxindoles with nitroalkenes catalyzed by nickel/PyBisulidine.

A Ni/PyBisulidine catalyzed asymmetric Michael addition of 3-acyloxy-2-oxindoles to nitroalkenes has been developed. Various quaternary substituted 3-acyloxy-2-oxindoles were obtained with excellent yields and diastereo- and enantioselectivities in a low-toxic green solvent, ethyl acetate, with a low catalyst loading (1 mol%). The reaction process is air and moisture tolerant. The substrate scope was also extended to α,ß-disubstituted nitroalkenes and 3-hydroxy-2-oxindoles, and good results were obtained.