LAUSR

To develop Rh-catalyzed dehydrocoupling for stereocontrolled synthesis of P–P bonds, we prepared potential intermediates, chiral rhodium phosphine-phosphido complexes, and investigated their stoichiometric and catalytic transformations. Treatment of [Rh(diphos*)(COD)][X] with the bis(secondary phosphine) IsHPCH2PHIs (1, Is = 2,4,6-(i-Pr)3C6H2) gave the cations [Rh(diphos*)(IsHPCH2PHIs)][X] (diphos* = (R,R)-Me-DuPhos (2), (R,R)-i-Pr-DuPhos (3), or (R,R)-Me-BPE (4); X = BF4 or OTf) with high diastereoselectivity as single C2-symmetric diastereomers. Deprotonation of 2–4 with NaN(SiMe3)2 yielded phosphine-phosphido chelates Rh(diphos*)(IsHPCH2PIs) 5–7 with high diastereoselectivity. Thermolysis of 5–7 in toluene at 90 °C caused isomerization to give Rh(diphos*)(IsMeP-PIs) (8–10) as mixtures of diastereomers. Under catalytic conditions, Rh-DuPhos precursors slowly converted 1 to a mixture of diastereomers of its isomer, the unsymmetrical diphosphine IsHP-PMeIs (12). We propose a possible mechanism for the iso...