Abstract
We synthesized chiral phosphoric acids bearing 3,3'-substituents starting from (R)-BINOL and demonstrated their catalytic activity as chiral Brønsted acid. Proper choice of the 3,3'-substituents of the phosphoric acid is critical to attain excellent enantioselectivity. We wish to describe in this article the background of development of the catalyst, design of the catalyst, and application of them to a range of asymmetric reactions: (1) nucleophilic addition to aldimines, (2) cycloaddition toward aldimines, (3) Friedel-Crafts alkylation of indoles with nitroalkene, α,β-unsaturated ketone, and trifluoropyruvate, (4) kinetic resolution in the intramolecular aldol reaction, and (5) desymmetrization in the intramolecular aldol reaction. We also studied the role of the phosphoric acid and elucidated that phosphoryl oxygen played a critical role as a Lewis basic site.
