We report the development of ac hiral guanidinebased copper(I) catalyst for the asymmetric azide-alkyne cycloaddition/[2+ +2] cascade reaction. Optically active spiroazetidinimine oxindoles were constructed by trapping the ketenimine species under mild reaction conditions.H igh level of enantioinduction and excellent isolated yields were achieved in the three-component reaction of various isatin-derived ketimines,s ulfonyl azides,a nd terminal alkynes.C ontrol experiments and X-ray crystallography were used to probe into the interaction of chiral guanidinium salt with copper salt. Scheme 1. Transformations beyond copper-catalyzed azide-alkyne cycloadditiono fN-sulfonyla zides.

A chiral N,N'-dioxide-nickel(II) complex-catalyzed asymmetric amination of 3-bromo-3-substituted oxindoles with anilines has been developed. A series of alkyl or aryl 3amino-indolinones with quaternary stereocenters were obtained in high yields with excellent ee values in one step (up to 99 % yield, up to 96 % ee). The method provided a ready route to optically active intermediates of 3-amino-2oxindole-based bioactive compounds. Moreover, a possible transition-state model is proposed so as to elucidate the origin of the chirality based on the X-ray crystal structure of the catalyst and the adduct.

Asymmetric catalytic tandem cycloisomerization/[3+2] cycloaddition was achieved by a combined system of Au(I) and chiral N,Nʹ-dioxide–Dy(III) complex. Various enantioenriched 3H-spiroisobenzofuran-1,3'-pyrrolidine derivatives from a number of 2,2-diester aziridines and 2-ethynyl benzyl...

Chiral polycyclic spiroindolenine is a frequently occurring structure unit in various biologically active natural products and pharmaceutical agents. The quest for facile and efficient methods for assembling such architecture from...

We report the development of ac hiral guanidinebased copper(I) catalyst for the asymmetric azide-alkyne cycloaddition/[2+ +2] cascade reaction. Optically active spiroazetidinimine oxindoles were constructed by trapping the ketenimine species under mild reaction conditions.H igh level of enantioinduction and excellent isolated yields were achieved in the three-component reaction of various isatin-derived ketimines,s ulfonyl azides,a nd terminal alkynes.C ontrol experiments and X-ray crystallography were used to probe into the interaction of chiral guanidinium salt with copper salt. Scheme 1. Transformations beyond copper-catalyzed azide-alkyne cycloadditiono fN-sulfonyla zides.