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摘要
The organopalladium complex containing ortho-metalated (S)-[1-(dimethylamino)ethyl]naphthalene as the chiral auxiliary has been successfully employed to promote the asymmetric Diels-Alder reaction between 3,4-dimethyl-1-phenylphosphole and (Z)-diphenyl-1-styrylphosphine or (E)-diphenyl-1-styrylphosphine. In the intramolecular cycloaddition reaction between (E)-diphenyl-1-styrylphosphine and 3,4-dimethyl-1-phenylphosphole, a pair of diastereomeric endo-cycloadducts were obtained in the ratio of 1: 1. However, the asymmetric reaction between (Z)-diphenyl-1-styrylphosphine and 3,4-dimethyl-1-phenylphosphole also produced the same endo-product in the same stereoselectivity unexpectedly. The chiral naphthylamine auxiliary could be removed chemoselectively from the template by treatment with concentrated hydrochloric acid to generate the neutral stable dichloro complex [(P-P) PdCl2]. Treatment of the dichloro complex with KCN gave the pure bis-phosphine ligand in quantitative yield.
