Design and Preparation of a Chiral Ligand Based on a Pseudorotaxane Skeleton: Application to Rhodium-Catalyzed Enantioselective Hydrogenation of Enamides

摘要

Supramolecular chemistry is one of the most rapidly growing areas of chemistry and greatly contributes to the development of numerous new innovative concepts in nanotechnology and molecular machines. In this area, interlocked molecules such as cat-enanes, rotaxanes, and pseudorotaxanes have currently attracted a great deal of interest because of not only their peculiar structures but also their unique properties that can be applied to molecular shuttles, molecular wires, and drug delivery systems. Especially, the combination of secondary ammonium salts and crown ethers has been extensively studied in rotaxane and pseudorotaxane synthesis because of their structural diversity and the high stability of crown ether/ammonium salt complexes. The rotaxane and pseudorotaxane molecules can provide unique chemical fields based on noncovalent bonding between crown ethers and ammonium salts, but much less attention has so far been paid to the use of such chemical fields for synthetic reactions.