关键词: 布朗斯特酸催化, 有机小分子催化, 1,1-二芳基乙烷, 邻羟基苯乙烯, 吲哚, 邻亚甲基苯醌

The skeleton of 1,1-diarylethane exists in many biologically important molecules. So, the synthesis of 1,1-diarylethanes has absorbed great attention from the chemists. This work has established a reaction of ortho-hydroxylstyrenes with indoles in the presence of racemic phosphoric acid, leading to the efficient synthesis of a series of 1,1-diarylethanes with structural diversity in high yields (up to 99%). This reaction is based on the fact that ortho-hydroxylstyrenes could transform into ortho-quinone methide under the catalysis of racemic phosphoric acid. The dual activation mode of racemic phosphoric acid to ortho-quinone methide and indole via forming two hydrogen bonds contributed greatly to the efficiency of the reaction. The mild reaction condition and wide substrate scope of the reaction will not only provide a useful strategy for solving the problems of residual metal and harsh reaction condition associated with metal catalysis, but also expand the applicability of organocatalytic reactions for the synthesis of 1,1-diarylethanes.

Key words: Brø, nsted acid catalysis, organocatalysis, 1,1-diarylethane, ortho-hydroxylstyrene, indole, ortho-quinone methide