Cu-catalyzed carbonyl hydrosilylation involves a ligated “[(L)CuH]” as the active catalyst, where the ligand L has a crucial role toward the stability, stereoselectivity, and enhancement of the hydridicity. Strongly σ-donating N-heterocyclic carbenes (NHCs), their ring-expanded form, and an abnormal NHC as ligands have yielded robust and efficient Cu catalysts. However, cyclic(alkyl)(amino)carbenes (CAACs), despite being stronger σ-donors than NHCs and already having a salient Cu^(I) chemistry, are yet to be reported as a similar ligand platform for this purpose. We establish here the familiar [(^Me2CAAC)CuCl] as a powerful precatalyst in this regard. Additionally, it also catalyzes the more challenging ester hydrosilylation, which is a rare feat for a Cu catalyst. Apart from the stronger σ-donating ability, the more steric “openness” of CAACs than bulky NHCs also seems to be advantageous. To corroborate, three new (CAAC)CuCl complexes [(^ArCH2,MeCAAC)CuCl] (Ar = Ph, 1-naphthyl, and 1-prenyl) are devised, where the effective steric around the copper is practically unaltered from the case of [(^Me2CAAC)CuCl]. All three are equally active in carbonyl and ester hydrosilylation as [(^Me2CAAC)CuCl]. Computation suggests the carbonyl insertion into a “(CAAC)Cu–H” as the rate-limiting step. To elucidate the involvement of a “(CAAC)CuH”, “(^PhCH2,MeCAAC)CuH” is generated in situ and is trapped as its BH₃ adduct (^PhCH2,MeCAAC)CuBH₄.

中文翻译：

---

(CAAC)CuCl：一种有效的羰基和酯氢化硅烷化预催化剂


铜催化的羰基氢化硅烷化涉及连接的“[(L)CuH]”作为活性催化剂，其中配体L对于稳定性、立体选择性和氢化性的增强起着至关重要的作用。强σ-供体N-杂环卡宾（NHC）、它们的扩环形式和异常NHC作为配体已经产生了稳健且高效的Cu催化剂。然而，尽管环状（烷基）（氨基）卡宾（CAAC）是比 NHC 更强的 σ-供体并且已经具有显着的 Cu ^(I)化学性质，但尚未报道为此目的的类似配体平台。我们在此建立了熟悉的[( ^Me2 CAAC)CuCl]作为这方面的强大预催化剂。此外，它还可以催化更具挑战性的酯氢化硅烷化反应，这对于铜催化剂来说是一项罕见的壮举。除了更强的 σ 捐赠能力之外，CAAC 比庞大的 NHC 更具空间“开放性”似乎也具有优势。为了证实这一点，设计了三种新的 (CAAC)CuCl 配合物 [( ^ArCH2,Me CAAC)CuCl]（Ar = Ph、1-萘基和 1-异戊二烯基），其中铜周围的有效空间实际上与[( ^Me2 CAAC)CuCl]。这三种物质在羰基和酯氢化硅烷化中的活性与 [( ^Me2 CAAC)CuCl] 相同。计算表明将羰基插入“(CAAC)Cu– H ”作为限速步骤。为了阐明“(CAAC)CuH”的参与，“( ^PhCH2,Me CAAC)CuH”原位生成，并以其BH ₃加合物( ^PhCH2,Me CAAC)CuBH ₄的形式被捕获。