He Chenxi, Ma Foqing, Zhang Wei, Tong Rongbiao
Department of Chemistry and Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), The Hong Kong University of Science and Technology, Clearwater Bay, Kowloon, 999077 Hong Kong, China.
Org Lett. 2022 May 20;24(19):3499-3503. doi: 10.1021/acs.orglett.2c01133. Epub 2022 May 6.
In 2003, Martı́n et al. reported a green alcohol oxidation with FeBr(cat.)/HO and proposed a high-valent iron species (HIS) responsible for the alcohol oxidation. Reinvestigating this FeBr(cat.)/HO method led us to propose a different mechanism that involves a reactive brominating species (RBS) for the oxidation of alcohols. The evidence to support this RBS-based mechanism includes (1) our recent findings of -generated RBS from the related FeBr/HO or CeBr/HO systems, (2) our results of a series of controlled experiments, and (3) some related RBS-based precedents (NBS, NBA, or Br) showing similar high oxidation selectivity of secondary over primary alcohols. These studies enable us to discover that a RBS from CeBr/HO is much more efficient for the oxidation of secondary and benzylic alcohols, which represents a new green protocol for selective oxidation of alcohols to carbonyls.
2003年，马丁等人报道了用FeBr（催化量）/HO进行的绿色醇氧化反应，并提出了一种负责醇氧化的高价铁物种（HIS）。对这种FeBr（催化量）/HO方法的重新研究使我们提出了一种不同的机制，该机制涉及一种用于醇氧化的活性溴化物种（RBS）。支持这种基于RBS机制的证据包括：（1）我们最近从相关的FeBr/HO或CeBr/HO体系中生成RBS的发现；（2）我们一系列对照实验的结果；（3）一些基于RBS的相关先例（NBS、NBA或Br），它们显示出仲醇相对于伯醇具有相似的高氧化选择性。这些研究使我们发现，CeBr/HO产生的RBS对仲醇和苄醇的氧化效率更高，这代表了一种将醇选择性氧化为羰基的新绿色方法。
