Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo, Hokkaido 060-0810, Japan.
Institute for Chemical Reaction Design and Discovery (WPI-ICReDD), Hokkaido University, Sapporo, Hokkaido 001-0021, Japan.
J Am Chem Soc. 2022 Feb 9;144(5):2218-2224. doi: 10.1021/jacs.1c11526. Epub 2022 Jan 6.
We report a visible-light-induced copper-catalyzed highly enantioselective umpolung allylic acylation reaction with acylsilanes as acyl anion equivalents. Triplet-quenching experiments and DFT calculations supported our reaction design, which is based on copper-to-acyl metal-to-ligand charge transfer (MLCT) photoexcitation that generates a charge-separated triplet state as a highly reactive intermediate. According to the calculations, the allylic phosphate substrate in the excited state undergoes novel molecular activation into an allylic radical weakly bound to the copper complex. The allyl radical fragment undergoes copper-mediated regio- and stereocontrolled coupling with the acyl group under the influence of the chiral N-heterocyclic carbene ligand.
我们报告了一种可见光诱导的铜催化高对映选择性反转烯丙基酰化反应，酰基硅烷作为酰基阴离子等价物。三重态猝灭实验和 DFT 计算支持了我们的反应设计，该设计基于铜到酰基的金属-配体电荷转移（MLCT）光激发，生成一个电荷分离的三重态作为高反应性中间体。根据计算，激发态下的烯丙基磷酸酯底物经历了新颖的分子活化，形成与铜配合物弱结合的烯丙基自由基。在手性 N-杂环卡宾配体的影响下，烯丙基自由基片段在铜介导的区域和立体控制偶联与酰基基团。
