Platinum-Catalyzed Asymmetric Alkylation of Secondary Phosphines: Enantioselective Synthesis of P-Stereogenic Phosphines
摘要:
The chiral Pt catalyst precursor Pt((R,R)-Me-Duphos)(Ph)(Cl) mediated alkylation of racemic secondary phosphines PHR(R') with benzyl halides in the presence of base to give enantioenriched tertiary phosphines PR(R')(CH2Ar). Similar reactions of bis(secondary) phosphines yielded chiral diphosphines in up to 93% ee and with good rac/meso diastereoselection.
Platinum-Catalyzed Asymmetric Alkylation of a Secondary Phosphine: Mechanism and Origin of Enantioselectivity
作者:Corina Scriban、David S. Glueck、James A. Golen、Arnold L. Rheingold
DOI:10.1021/om061116s
日期:2007.3.1
formed by proton transfer from 2 to the silanolate ligand in Pt((R,R)-Me-Duphos)(Ph)(OSiMe3) (5), which was generated from 1 (or from Pt((R,R)-Me-Duphos)(Ph)(Br) (7)) and NaOSiMe3. The silanolate complex 5 reacted with water to yield Pt((R,R)-Me-Duphos)(Ph)(OH) (6); both 6 and 7 were crystallographically characterized. The stoichiometric reaction of 4 and benzyl bromide in toluene gave the bromide
催化剂前体Pt((R,R)-Me-Duphos)(Ph)(Cl)(1)介导的仲膦PHMe(Is)(2 ; Is = 2,4,6-(i -Pr )3 C 6 H 2)在碱式NaOSiMe 3的存在下用苄基溴生成对映体富集的PMeIs(CH 2 Ph)(3)。在对各个化学计量步骤的研究的基础上,已经提出了一种催化机理。末端磷酸络合物Pt((R,R)-Me-Duphos)(Ph)(PMeIs)(4)由2的质子转移形成在PT中的硅醇盐配体(([R ,- [R)-Me-DUPHOS)(PH)(OSiMe 3)(5),其产生从1(或选自Pt(([R ,- [R)-Me-DUPHOS)(PH )(Br)(7))和NaOSiMe 3。硅烷醇配合物5与水反应,生成Pt((R,R)-Me-Duphos)(Ph)(OH)(6); [ M + H] + 。既6和7进行了晶体学表征。4和苄基溴在甲苯中的化学计量反应
WO2007/16264
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Platinum-Catalyzed Asymmetric Alkylation of Secondary Phosphines: Enantioselective Synthesis of P-Stereogenic Phosphines
作者:Corina Scriban、David S. Glueck
DOI:10.1021/ja058096q
日期:2006.3.1
The chiral Pt catalyst precursor Pt((R,R)-Me-Duphos)(Ph)(Cl) mediated alkylation of racemic secondary phosphines PHR(R') with benzyl halides in the presence of base to give enantioenriched tertiary phosphines PR(R')(CH2Ar). Similar reactions of bis(secondary) phosphines yielded chiral diphosphines in up to 93% ee and with good rac/meso diastereoselection.