Molecular Recognition in a Palladium Complex Promoted Asymmetric Synthesis of a <i>P</i>-Chiral Heterodifunctionalized Bidentate Phosphine Ligand

Abstract

The organopalladium complex containing orthometalated (S)-(1-(dimethylamino)ethyl)naphthalene as the chiral auxiliary has been used successfully to promote the asymmetric [4+2] Diels−Alder reaction between 3,4-dimethyl-1-phenylphosphole and 2-methylene-3-quinuclidinone. In this reaction, the organopalladium template exhibited remarkable stereochemical and electronic directing effects such that the quinuclidinone-nitrogen atom in the resulting phosphanorbornene cycloadduct is located stereospecifically in the exo position. Only one enantiomerically pure P−N bidentate ligand was obtained, although four diastereomeric products are possible. The absolute configuration and the coordination properties of the P-chiral cycloadduct have been established by single-crystal X-ray analyses.