Laguerre Netgie, Riehl Paul S, Oblinsky Daniel G, Emmanuel Megan A, Black Michael J, Scholes Gregory D, Hyster Todd K
Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States.
Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14850, United States.
ACS Catal. 2022 Aug 5;12(15):9801-9805. doi: 10.1021/acscatal.2c02294. Epub 2022 Jul 27.
Allylations are practical transformations that forge C-C bonds while introducing an alkene for further chemical manipulations. Here, we report a photoenzymatic allylation of -chloroamides with allyl silanes using flavin-dependent 'ene'-reductases (EREDs). An engineered ERED can catalyze annulative allylic alkylation to prepare 5, 6, and 7-membered lactams with high levels of enantioselectivity. Ultrafast transient absorption spectroscopy indicates that radical termination occurs via β-scission of the silyl group to afford a silyl radical, a distinct mechanism by comparison to traditional radical allylations involving allyl silanes. Moreover, this represents an alternative strategy for radical termination using EREDs. This mechanism was applied to intermolecular couplings involving allyl sulfones and silyl enol ethers. Overall, this method highlights the opportunity for EREDs to catalyze radical termination strategies beyond hydrogen atom transfer.
烯丙基化反应是一类实用的转化反应,它在构建碳-碳键的同时引入烯烃以便进行进一步的化学操作。在此,我们报道了使用黄素依赖性“烯”还原酶(EREDs)催化的氯代酰胺与烯丙基硅烷的光酶促烯丙基化反应。一种经过工程改造的ERED能够催化环化烯丙基烷基化反应,以高对映选择性制备5元、6元和7元内酰胺。超快瞬态吸收光谱表明,自由基终止是通过硅烷基的β-断裂产生硅烷基自由基,这与涉及烯丙基硅烷的传统自由基烯丙基化反应相比是一种独特的机制。此外,这代表了一种使用EREDs进行自由基终止的替代策略。该机制被应用于涉及烯丙基砜和烯醇硅醚的分子间偶联反应。总体而言,该方法凸显了EREDs催化超越氢原子转移的自由基终止策略的可能性。