A highly enantioselective formal hydroformylation of vinyl arenes enabled by copper hydride (CuH) catalysis is reported. Key to the success of the method was the use of the mild Lewis acid zinc triflate to promote the formation of oxocarbenium electrophiles through the activation of diethoxymethyl acetate. Using the newly developed protocol, a broad range of vinyl arene substrates underwent efficient hydroacetalization reactions to provide access to highly enantioenriched α-aryl acetal products in good yields with exclusively branched regioselectivity. The acetal products could be converted to the corresponding aldehydes, alcohols, and amines with full preservation of the enantiomeric purity. Density functional theory studies support that the key C–C bond-forming event between the alkyl copper intermediate and the oxocarbenium electrophile takes place with inversion of configuration of the Cu–C bond in a backside S_E2-type mechanism.

中文翻译：

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CuH 催化乙烯基芳烃的区域选择性和对映选择性形式加氢甲酰化


据报道，氢化铜 (CuH) 催化下乙烯基芳烃的高度对映选择性形式加氢甲酰化。该方法成功的关键是使用温和的路易斯酸三氟甲磺酸锌通过激活乙酸二乙氧基甲酯来促进氧碳鎓亲电子试剂的形成。使用新开发的方案，多种乙烯基芳烃底物进行了有效的加氢缩醛化反应，以良好的产率和专门支化的区域选择性获得高度对映体富集的α-芳基缩醛产品。缩醛产物可以转化为相应的醛、醇和胺，并完全保持对映体纯度。密度泛函理论研究支持烷基铜中间体和氧碳鎓亲电子试剂之间的关键 C-C 键形成事件是通过背面 S _E 2 型中 Cu-C 键构型的反转而发生的机制。