Asymmetric synthesis of chiral trifluoromethylated heliotridanevia highly catalytic asymmetric Friedel–Crafts alkylation with β-trifluoromethylated acrylates and pyrroles

Abstract

Chiral Ph-dbfox (Ph-dbfox = (R,R)-4,6-dibenzofurandiyl-2,2′-bis(4-phenyloxazoline))/Zn(NTf₂)₂ catalyzed enantioselective Friedel–Crafts reactions of β-CF₃ acrylates with pyrroles and indoles have been investigated, which afforded the corresponding chiral trifluoromethyl pyrrole and indole derivatives in high yields (90–99%) with a range of 66–99% ee values. With the aid of the chiral adduct of the asymmetric Friedel–Crafts reaction, the chiral trifluoromethylated heliotridane has been successfully constructed in good total yield.