Achiral Cp*Rh(III)/Chiral Lewis Base Cooperative Catalysis for Enantioselective Cyclization via C-H Activation.

An enantioselective [4+3] cyclization via C(sp2)-H activation with a cooperative catalytic system consisting of a Cp*Rh(III) complex and a chiral Lewis base is described. An α,ß-unsaturated acyl ammonium intermediate is generated from a chiral isochalcogenurea catalyst and an acyl fluoride reacts with a metallacycle generated from the Cp*Rh catalyst and a benzylamine derivative. This cooperative catalytic system gives a variety of benzolactams in good yields with excellent enantioselectivities (up to 99:1 er). The results demonstrated that chiral Lewis base catalysis is a powerful tool for controlling the enantioselectivity of transition metal-catalyzed C-H functionalizations.

Synthesis of 1,1'-Spirobiindane-7,7'-Disulfonic Acid and Disulfonimide: Application for Catalytic Asymmetric Aminalization.

1,1'-Spirobiindane-7,7'-disulfonic acid (SPISA) and 1,1'-spirobiindane-7,7'-disulfonimide were synthesized from 1,1'-spirobiindane-7,7'-diol (SPINOL) in 4 steps using a Pd-catalyzed Newman-Kwart rearrangement as a key step. These new catalysts possessing a rigid spirocyclic backbone were evaluated in a catalytic asymmetric aminalization reaction, and SPISA/iPr2 NEt exhibited high enantioselectivity, demonstrating the utility of SPISA as a chiral Brønsted acid catalyst.