Caló Fabio P, Fürstner Alois
Max-Planck-Institut für Kohlenforschung, 45470, Mülheim/Ruhr, Germany.
Angew Chem Int Ed Engl. 2020 Aug 10;59(33):13900-13907. doi: 10.1002/anie.202004377. Epub 2020 Jun 4.
The heteroleptic dirhodium paddlewheel catalyst 7 with a chiral carboxylate/acetamidate ligand sphere is uniquely effective in asymmetric [2+1] cycloadditions with α-diazo-α-trimethylstannyl (silyl, germyl) acetate. Originally discovered as a trace impurity in a sample of the homoleptic parent complex [Rh ((R)-TPCP) ] (5), it is shown that the protic acetamidate ligand is quintessential for rendering 7 highly enantioselective. The -NH group is thought to lock the ensuing metal carbene in place via interligand hydrogen bonding. The resulting stannylated cyclopropanes undergo "stereoretentive" cross coupling, which shows for the first time that even chiral quarternary carbon centers can be made by the Stille-Migita reaction.
具有手性羧酸盐/乙酰胺配体球的异核双铑桨轮催化剂7在与α-重氮-α-三甲基锡基（硅基、锗基）乙酸酯的不对称[2+1]环加成反应中具有独特的效果。最初在同核母体配合物[Rh((R)-TPCP)]（5）的样品中作为痕量杂质被发现，结果表明质子化的乙酰胺配体对于使7具有高度对映选择性至关重要。据认为，-NH基团通过配体间氢键将生成的金属卡宾固定在位。所得的锡基化环丙烷进行“立体保持”交叉偶联，这首次表明通过施蒂勒-三木反应甚至可以构建手性季碳中心。
