Department of Chemistry and Biochemistry , University of Denver , Denver , Colorado 80208 , United States.
J Org Chem. 2018 Sep 7;83(17):10688-10692. doi: 10.1021/acs.joc.8b01517. Epub 2018 Aug 23.
The radical formed by reduction of 5-bromo-6-oxo-6-phenylhexyl methanesulfonate, an α-bromoketone, with SmI was spin trapped with 2-methyl-2-nitrosopropane. Electron paramagnetic resonance spectra of the spin adduct and the adduct formed in the analogous reaction with selectively deuterated substrate identify the radical intermediate in this SmI reduction as a carbon-centered radical. This result supports the proposal that the formation of reactive Sm-enolates arises from reduction of the carbon-bromine bond rather than a ketyl radical anion.
5-溴-6-氧代-6-苯基己基甲磺酸酯（一种α-溴代酮）经 SmI 还原形成的自由基，用 2-甲基-2-亚硝基丙烷进行自旋捕获。自旋加合物和用选择性氘代底物进行类似反应形成的加合物的电子顺磁共振谱鉴定了这种 SmI 还原中的自由基中间体为碳中心自由基。这一结果支持了这样的假设，即反应性 Sm-烯醇盐的形成是源于碳-溴键的还原，而不是酮自由基阴离子。
