Deprotonation of phenyldibenzo[b,f]tropylidene (8) with LDA/t-BuOK followed by quenching with either diastereomer of inexpensive glucose-based t-Bu-sulfinate (R)- or (S)-11 affords a sulfoxide–alkene hybrid ligand as the diastereomeric pairs (S_S,S_C)-9/(S_S,R_C)-10 and (R_S,R_C)-9/(R_S,S_C)-10, respectively, which via chromatographic/recrystallization may be separated into the four isomers. The optically pure diastereomeric ligands (S_S,S_C)-9 and (S_S,R_C)-10 react with [RhCl(coe)₂]₂ to form the dinuclear complexes (R_S,S_C)-11 and (R_S,R_C)-12, respectively, in which the bidentate ligands coordinate the metal centers through the sulfur and alkene donor functions. These complexes catalyze the conjugate addition of arylboronic acids to cyclic Michael acceptors with enantioselectivities of up to 99% ee. DFT calculations show the preponderant influence of planar chirality of the ligand alkene function. The enantioselectivity switch observed between (R_S,S_C)-11 and (R_S,R_C)-12 is explained by the inverted cis–trans coordinations of the substrate molecules in catalytic steps.

中文翻译：

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手性Rh（I）配合物的三环亚砜-烯烃杂配体：“匹配”的非对映异构体催化不对称的CC键形成

苯基二苯并[去质子化B，F ] tropylidene（8）用LDA /吨-BuOK基葡萄糖接着用廉价的非对映体任一淬火吨-Bu-亚磺酸盐（[R或（ - ）小号） - 11次，得到亚砜烯烃混合（S _S ，S _C）-9 /（S _S ，R _C）-10和（R _S ，R _C）-9 /（R _S ，S _C）-10的非对映体对分别通过色谱/重结晶可将其分离成四个异构体。光学纯的非对映体配体（S _S ，S _C）-9和（S _S ，R _C）-10与[RhCl（coe）₂ ] ₂反应形成双核络合物（R _S ，S _C）-11和（R _S ，R _C）-12，其中双齿配体通过硫和烯烃供体的功能配位金属中心。这些络合物以高达99％ee的对映选择性催化芳基硼酸与环状Michael受体的共轭加成。DFT计算显示了配体烯烃官能团的平面手性的主要影响。在（R _S ，S _C）-11和（R _S ，R _C）-12之间观察到的对映选择性转换是通过底物分子在催化步骤中的顺-反式配位而解释的。