Bimetallic Rhodium(II)/Indium(III) Relay Catalysis for Tandem Insertion/Asymmetric Claisen Rearrangement.

The first example of catalytic insertion/asymmetric Claisen rearrangement tandem reaction of N-sulfonyl-1,2,3-triazoles with allyl alcohol esters was achieved by bimetallic relay catalytic systems involving achiral rhodium salt and chiral N,N'-dioxide-indium(III) complex. This manifold could overcome the limitation of single RhII catalysis, providing a straight and facile route to various enantioenriched β/γ-amino acid derivatives in high yields (up to 99 %) with excellent diastereo- and enantioselectivities (up to >95:5 dr, 98:2 er). Moreover, possible transition state models were proposed to elucidate the origin of chiral induction based on the control experiments and X-ray crystal structure of the catalyst.