Electron-Withdrawing, Biphenyl-2,2′-diol-Based Compounds for Asymmetric Catalysis

Facile synthetic routes to a chiral chloro‐substituted biphenyl‐2,2′‐diyl hydrogen phosphate and a chiral O,O‐biphenyl‐2,2′‐diyl phosphoramidothioate are described. The performance of these compounds as catalysts for the hydrophosphonylation of imines and the Friedel–Crafts alkylation of indole was investigated. In the latter reaction, the chloro‐substituted phosphoric acid derivative was found to rival the best Brønsted acid catalysts reported to date. Efficient synthetic routes to a chiral chloro‐substituted biphenyl‐2,2′‐diyl hydrogen phosphate and a chiral O,O‐biphenyl‐2,2′‐diyl phosphoramidothioate are described. The performance of these compounds as catalysts for the hydrophosphonylation of imines and the Friedel–Crafts alkylation of indole are reported.