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Design of Phosphinic Acid Catalysts with the Closest Stereogenicity at the α‑Position: Synthesis and Application of α‑Stereogenic Perfluoroalkyl Phosphinic Acid Catalysts

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journal contribution
posted on 2019-04-19, 15:11 authored by Kohei Fujii, Haruki Todani, Shigekazu Ito, Koichi Mikami
Chiral C2-symmetric phosphinic acids were designed based on sterically demanding and helical chiral perfluoroalkyl groups at the closest α-position advancing asymmetric reaction environment and catalytic activity. The perfluoroalkyl catalysts, [(CF3)2F2] and [(C2F5)2F2] phosphinic acids, were synthesized via a stereoselective addition/cyclization sequence of methyl phosphinate and deoxofluorination. These new classes of Brønsted acid catalysts were applied to an asymmetric Friedel–Crafts reaction to give up to 89% yield and 82% R-enantioselectivity, which is higher than those obtained with the parent phosphoric acid (42% and 55.5% S).