有機硫黄官能基を有する不斉配位子を用いた触媒的不斉合成

Abstract

Our recent results of catalytic asymmetric synthesis with chiral organosulfur ligands are reviewed. We have developed new chiral ligands with various coordinatable functionalities such as chiral sulfinyl, sulfenyl, phosphinyl, phosphinoamino, 1, 3-oxazoline, and imino groups, and applied them to Lewis acid- or transition metal-catalyzed asymmetric alkylations and cycloaddition reactions. The usefulness as chiral ligands in catalytic asymmetric alkylations and Diels-Alder reactions were demonstrated. The use of 2-phosphinophenyl and 2- (phosphi-noamino) phenyl 2-methoxy-1-naphthyl sulfoxide in palladium-catalyzed asymmetric alkylations provided high enantioselectivity (82 and 97%, respectively). 4- (1-Methoxyisopropyl) -2- [2- (2-methoxy- 1-naphthalenesulfinyl) phenyl] -1, 3-oxazoline was applied to MgI2-catalyzed Diels-Alder reactions as a chiral ligand, achieving high enantioselectivity (92%). Some of the structure of the intermediary metal complexes coordinated by the chiral ligands were determined by the X-ray crystallographic analysis. The mechanisms of the asymmetric synthesis with the ligands are proposed on the basis of the structure of the intermediary complexes and the stereo-chemical results obtained.