Chirality Breeding via Asymmetric Phosphination. Palladium-Catalyzed Diastereoselective Synthesis of a P-Stereogenic Phosphine

Methylation of the crystallographically characterized primary alkylphosphine-borane PH 2 Men(BH 3 ) ( 3, Men = (−)-menthyl) under phase-transfer conditions, followed by deprotection, gave the secondary phosphine PH(Me)(Men) ( 2 ). Cross-coupling of 2 with PhI in the presence of NaOSiMe 3 selectively gave S P -PPh(Me)(Men) ( 1, L) with a variety of Pd catalyst precursors, including a complex of diastereopure S P - 1, trans -PdL 2 (Ph)(I) ( 6a ). In this reaction, the chiral phosphine L formally acted as a ligand in catalysis of its selective self-reproduction, but 6a was partially transformed to its diastereomers, trans -Pd( S P - 1 )( R P - 1 )(Ph)(I) ( 6b ) and trans -Pd( R P - 1 ) 2 (Ph)(I) ( 6c ), and several other intermediates were observed during catalysis.