Design of highly functional small-molecule catalysts and related reactions based on acid-base combination chemistry

The design of small but highly functional artificial catalysts is very important for practical organic synthesis. We have succeeded in the rational design of small and simple catalysts and related reactions based on acid-base combination chemistry. Acid-base combined catalysts can be classified into three types: (i) acid-base combined salt catalysts, (ii) conjugate acid-base catalysts, and (iii) nonconjugate acid-base catalysts. We have systematically developed acid-base combined salt catalysts such as ammonium salts, ate complexes, ion pairs and cation-π complexes, acid-base conjugate catalysts such as metal oxides (monoconjugation) and zinc(II)-3,3′-diphosphinol- BINOLates (triconjugation), and acid-base non-conjugate catalysts like L-histidine-derived sulfonamides. 1 Introduction 2 General Concept for the Design of Catalysts Based on Acid-Base Combination Chemistry 3 Catalytic Dehydrative Monoesterification of Phosphoric Acid with Alcohols Based on Acid-Base Combination Chemistry 4 Acid-Base Combined Salt Catalysts (Type A) 4.1 Brønsted Acid-Brønsted Base Combined Salt Catalysts (Type A-1) 4.2 Lewis Acid-Lewis Base Combined Salt Catalysts and Reagents (Type A-2) 4.3 Cation-Anion-Pair Catalysts (Type A-3) 4.4 Cation-n Complex Catalysts (Type A-4) 5 Lewis Acid-Lewis Base Conjugate Catalysts (Type B) 5.1 Molybdenum Oxides as Highly Effective Dehydrative Cyclization Catalysts Directed toward the Synthesis of Oxazolines and Thiazolines (Type B-1) 5.2 Zinc(II)-3,3′-Diphosphinoyl- BINOLates in the Asymmetric Addition of Organozinc Reagents to Aldehydes (Type B-2) 6 Brønsted Acid-Lewis Base Nonconjugate Asymmetric Catalysts (Separated Type) (Type C) 6.1 L-Histidine-derived Sulfonamide as a Minimal Artificial Acylase for the Kinetic Resolution of Racemic Alcohols 7 Conclusions.