Synthesis, Structure, Dynamics, and Selective Methylation of Platinum and Palladium Diphosphametallacyclobutane Complexes

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• 作者：Timothy W. Chapp ; Adam J. Schoenfeld ; Matthew D. Sanderson ; Cory L. Chang ; David S. Glueck ; James A. Golen ; Curtis E. Moore ; Arnold L. Rheingold
• 刊名：Organometallics
• 出版年：2012
• 出版时间：August 13, 2012
• 年：2012
• 卷：31
• 期：15
• 页码：5573-5585
• 全文大小：573K
• 年卷期：v.31,no.15(August 13, 2012)
• ISSN：1520-6041

文摘

Treatment of M(dppe)Clb>2b> (M = Pd, Pt) or Pt((R,R)-Me-DuPhos)Clb>2b> with IsHPCHb>2b>PHIs (<b>1b>; Is = isityl = 2,4,6-(i-Pr)b>3b>Cb>6b>Hb>2b>) and 2 equiv of NaOSiMeb>3b> gave the mononuclear diphosphametallacyclobutane complexes M(dppe)(IsPCHb>2b>PIs) (M = Pd (<b>2b>), Pt (<b>3b>)), or Pt((R,R)-Me-DuPhos)(IsPCHb>2b>PIs) (<b>4b>). Dynamic processes involving phosphorus inversion and rotation about the P鈥揅(Is) bonds in <b>2b>鈥?b>4b> were characterized by variable-temperature NMR spectroscopy, which suggested that each existed as a single Cb>2b>-symmetric diastereomer in solution, consistent with their solid-state structures determined by X-ray crystallography. The MiniPhos derivative IsMePCHb>2b>PMeIs (<b>5b>) was prepared as a 5.5/1 rac/meso mixture by sequential arylation and methylation of Clb>2b>PCHb>2b>PClb>2b>. Alternatively, the catalyst precursor Pt((R,R)-Me-DuPhos)(Ph)(Cl) mediated alkylation of secondary phosphines in the presence of NaOSiMeb>3b> to yield selectively meso-<b>5b> either from PHMe(Is) and CHb>2b>Ib>2b> or from <b>1b> and MeI. Recrystallization and chromatography yielded diastereomerically enriched rac-<b>5b> and meso-<b>5b>. Treatment of M(dppe)(OTf)b>2b> (M = Pd, Pt) or Pt((R,R)-Me-DuPhos)(OTf)b>2b> with meso-<b>5b> gave the dications meso-[M(diphos)(IsMePCHb>2b>PMeIs)][OTf]b>2b> (M(diphos) = Pd(dppe) (<b>6b>), Pt(dppe) (<b>8b>), Pt((R,R)-Me-DuPhos) (<b>10b>)). Similar reactions of rac-<b>5b> yielded the dications rac-[M(diphos)(IsMePCHb>2b>PMeIs)][OTf]b>2b> (M(diphos) = Pd(dppe) (<b>7b>), Pt(dppe) (<b>9b>)) and a 1/1 mixture of the Cb>2b>-symmetric diastereomers [Pt((R,R)-Me-DuPhos)(IsMePCHb>2b>PMeIs)][OTf]b>2b> (<b>11ab>,<b>bb>). Treatment of <b>2b> and <b>3b> with 2 equiv of methyl triflate gave the dications <b>6b>鈥?b>9b> as ca. 1/1 meso/rac mixtures, and methylation of <b>4b> selectively gave one of the Cb>2b>-symmetric diastereomers, <b>11ab>. These alkylations proceeded via the observable monomethylated intermediates [M(diphos)(IsMePCHb>2b>PIs)][OTf] (<b>12b>鈥?b>14b>).