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Synthesis, Structure, Dynamics, and Enantioface-Selective η3-Benzyl Coordination in the Chiral Rhodium Complexes Rh(diphos*)(η3-CH2Ph)
Organometallics ( IF 2.5 ) Pub Date : 2020-10-16 , DOI: 10.1021/acs.organomet.0c00516
Perry M. Scheetz 1 , Sarah T. Chachula 1 , Russell P. Hughes 1 , David S. Glueck 1 , Curtis E. Moore 2 , Milan Gembicky 2 , Arnold L. Rheingold 2
Affiliation  

The rhodium benzyl complexes Rh(diphos*)(η3-CH2Ph) (114, diphos* = chiral bis(phosphine)), potential precursors for asymmetric catalysis, were prepared either by treatment of Rh(COD)(η3-CH2Ph) (15, COD = 1,5-cyclooctadiene) with diphos* or from the reaction of [Rh(diphos*)(Cl)]2 (1620) with PhCH2MgCl, and their structures and dynamics were investigated. For C2-symmetric diphos* (BPE and DuPhos derivatives, Me-FerroLANE, Et-FerroTANE, DIOP, BINAP), observation of one set of NMR signals for complexes 112 suggested that the two diastereomers in which different η3-benzyl enantiofaces were coordinated to rhodium interconverted rapidly on the NMR time scale via suprafacial shifts; observation of five inequivalent aryl 1H NMR signals showed that antarafacial shifts were slow on the NMR time scale. With the C1-symmetric ligands (R,S)-CyPF-t-Bu and (S,R)-Me-BoPhoz, complexes 13 and 14 gave rise to two sets of NMR signals, consistent with fast suprafacial shifts but slow antarafacial shifts on the NMR time scale. Density functional theory studies of the Me-DuPhos, Me-BPE, Ph-BPE, Me-FerroLANE, and CyPF-t-Bu benzyl complexes 1, 4, 7, 11, and 13 showed that enantioface-selective benzyl coordination involved small energy differences (0.4–2.7 kcal/mol). The barrier to interconversion between these isomers by suprafacial shifts was also low (2.2–7.1 kcal/mol), and the computed barrier for antarafacial shifts in Me-DuPhos complex 1 was significantly higher. Treatment of [Rh(COD)(Cl)]2 with PhCH2MgCl gave 15; excess Grignard reagent yielded the ate complex [Mg2Cl3(THF)6][Rh(COD)(η1-CH2Ph)2] (21). Benzyl complexes 11 and 13, 21, and dimers 1719 (diphos* = (R,R)-i-Pr-DuPhos, (R,R)-Me-FerroLANE, (R,R)-Ph-BPE) were structurally characterized by X-ray crystallography.

中文翻译:

的合成,结构,动力学,和Enantioface-选择性η 3 -苄协调在手性铑络合物的Rh(DIPHOS *)(η 3 -CH 2 PH)

铑络合物苄铑(DIPHOS *)(η 3 -CH 2 PH)(1 - 14,DIPHOS * =手性双(膦)),用于不对称催化潜在的前体,或是被治疗的Rh(COD)的制备(η 3 -CH 2 PH)(15,COD = 1,5-环辛二烯)与DIPHOS *或从的[Rh(DIPHOS *)(CL)]的反应216 - 20)与物理信道2的MgCl,以及它们的结构和动力学进行了调查。对于C 2-对称膦酸酯*(BPE和DuPhos衍生物,Me-FerroLANE,Et-FerroTANE,DIOP,BINAP),观察一组配合物的NMR信号1- 12表明,在其中不同的η两种非对映3 -苄基enantiofaces被配位到铑上经由suprafacial位移的NMR时间规模迅速相互转化; 五个不等价的芳基1 H NMR信号的观察结果表明,在NMR时间范围内,对等位移较慢。具有C 1对称配体(RS)-CyPF- t -Bu和(SR)-Me-BoPhoz,配合物1314产生了两组NMR信号,这与NMR时间尺度上的快速表面位移和缓慢的反面位移一致。的ME-DUPHOS中,Me-BPE,PH-BPE的密度泛函理论研究中,Me-FerroLANE,和CyPF--Bu苄基配合物14711,和13表明,enantioface选择性苄协调涉及小的能量差异(0.4–2.7 kcal / mol)。这些异构体之间通过表面转移而相互转化的障碍也很低(2.2–7.1 kcal / mol),并且在Me-DuPhos配合物1中计算出的对面转移的障碍也更高。的的[Rh(COD)(Cl)的]治疗2与物理信道2氯化镁得15 ; 过量的格氏试剂,得到根型配合物[镁23(THF)6 ]的[Rh(COD)(η 1 -CH 2 PH)2 ](21)。苄基配合物111321,和二聚物17 - 19(DIPHOS * =([R - [R )--Pr-DUPHOS(- [R - [R)-Me-FerroLANE,(- [R - [R)-Ph-BPE)为由X射线晶体学表征结构。
更新日期:2020-11-09
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