Pure and Applied Chemistry

Abstract: A series of chiral quaternary ammonium salts derived from commercially available (R)- or (S)-binaphthol have been designed as new C₂-symmetric chiral phase-transfer catalysts. In order to realize the flexible design of these phase-transfer catalysts, the combinatorial design approach has been developed. Chiral high-performance organocatalysts, thus obtained, have been successfully applied to the highly practical asymmetric synthesis of various amino acid derivatives, including α-alkyl and α,α-dialkyl-α-amino acids in addition to alkaloids. Furthermore, several chiral bifunctional phase-transfer catalysts have been designed and synthesized for effecting base-free phase-transfer reactions under essentially neutral conditions in order to realize green sustainable chemistry.