132399-64-5Relevant articles and documents
Synthesis, structure, dynamics, and selective methylation of platinum and palladium diphosphametallacyclobutane complexes
Chapp, Timothy W.,Schoenfeld, Adam J.,Sanderson, Matthew D.,Chang, Cory L.,Glueck, David S.,Golen, James A.,Moore, Curtis E.,Rheingold, Arnold L.
, p. 5573 - 5585 (2012)
Treatment of M(dppe)Cl2 (M = Pd, Pt) or Pt((R,R)-Me-DuPhos) Cl2 with IsHPCH2PHIs (1; Is = isityl = 2,4,6-(i-Pr) 3C6H2) and 2 equiv of NaOSiMe3 gave the mononuclear diphosphametallacyclobutane complexes M(dppe)(IsPCH 2PIs) (M = Pd (2), Pt (3)), or Pt((R,R)-Me-DuPhos)(IsPCH 2PIs) (4). Dynamic processes involving phosphorus inversion and rotation about the P-C(Is) bonds in 2-4 were characterized by variable-temperature NMR spectroscopy, which suggested that each existed as a single C2-symmetric diastereomer in solution, consistent with their solid-state structures determined by X-ray crystallography. The MiniPhos derivative IsMePCH2PMeIs (5) was prepared as a 5.5/1 rac/meso mixture by sequential arylation and methylation of Cl2PCH 2PCl2. Alternatively, the catalyst precursor Pt((R,R)-Me-DuPhos)(Ph)(Cl) mediated alkylation of secondary phosphines in the presence of NaOSiMe3 to yield selectively meso-5 either from PHMe(Is) and CH2I2 or from 1 and MeI. Recrystallization and chromatography yielded diastereomerically enriched rac-5 and meso-5. Treatment of M(dppe)(OTf)2 (M = Pd, Pt) or Pt((R,R)-Me-DuPhos)(OTf)2 with meso-5 gave the dications meso-[M(diphos)(IsMePCH2PMeIs)][OTf] 2 (M(diphos) = Pd(dppe) (6), Pt(dppe) (8), Pt((R,R)-Me-DuPhos) (10)). Similar reactions of rac-5 yielded the dications rac-[M(diphos)(IsMePCH 2PMeIs)][OTf]2 (M(diphos) = Pd(dppe) (7), Pt(dppe) (9)) and a 1/1 mixture of the C2-symmetric diastereomers [Pt((R,R)-Me-DuPhos)(IsMePCH2PMeIs)][OTf]2 (11a,b). Treatment of 2 and 3 with 2 equiv of methyl triflate gave the dications 6-9 as ca. 1/1 meso/rac mixtures, and methylation of 4 selectively gave one of the C2-symmetric diastereomers, 11a. These alkylations proceeded via the observable monomethylated intermediates [M(diphos)(IsMePCH2PIs)][OTf] (12-14).
