6533b821fe1ef96bd127b628

RESEARCH PRODUCT

Enantioselective Friedel-Crafts Alkylation of Indoles with (E)-1-Aryl-4-benzyloxybut-2-en-1-ones Catalyzed by an (R)-3,3′-Br2BINOLate-Hafnium(IV) Complex

subject

description

A highly enantioselective Friedel–Crafts reaction of unprotected indoles with (E)-1-aryl-4-benzyloxybut-2-en-1-ones catalyzed by a new chiral [Hf{(R)-3,3′-Br2-BINOL}(OtBu)2]2 complex has been developed to functionalize the C-3 position of the indole nucleus with a side chain bearing a 1,4-difunctionalized moiety and a benzylic stereogenic center. The reaction proceeds in good to excellent yields and excellent enantioselectivities (up to 97 % ee). The usefulness of this approach was illustrated with the synthesis of a tryptophol derivative.