已开发出一种无金属的非均相光催化系统,用于使用氧气作为氧化剂的高效苄基CH氧化。这种可见光介导的氧化反应利用石墨碳氮化物(gC 3 N 4)作为可回收,无毒且低成本的光催化剂。温和的反应条件可从易于获得的烷基芳族前体中以高收率生成合成和生物学上有价值的异苯并二氢醌,邻苯二甲酸,异喹啉酮,异吲哚啉酮和氧杂蒽。gC 3 N 4的异质性催化系统可轻松回收和循环利用,并可多次使用而不会损失活性。通过在生物活性和具有药物价值的靶标合成中的应用,进一步证明了这种“绿色”方法的综合效用。
Dehydrogenative α-Oxygenation of Ethers with an Iron Catalyst
作者:Angela Gonzalez-de-Castro、Craig M. Robertson、Jianliang Xiao
DOI:10.1021/ja502167h
日期:2014.6.11
Selective alpha-oxidation of ethers under aerobic conditions is a long-pursued transformation; however, a green and efficient catalytic version of this reaction remains challenging. Herein, we report a new family of iron catalysts capable of promoting chemoselective alpha-oxidation of a range of ethers with excellent mass balance and high turnover numbers under 1 atm of O-2 with no need for any additives. Unlike metalloenzymes and related biomimetics, the catalyst produces H-2 as the only byproduct. Mechanistic investigations provide evidence for an unexpected two-step reaction pathway, which involves dehydrogenative incorporation of O-2 into the ether to give a peroxobisether intermediate followed by cleavage of the peroxy bond to form two ester molecules, releasing stoichiometric H-2 gas in each step. The operational simplicity and environmental friendliness of this methodology affords a useful alternative for performing oxidation, while the unique ability of the catalyst in oxygenating a substrate via dehydrogenation points to a new direction for understanding metalloenzymes and designing new biomimetic catalysts.