Visible light mediated oxidation of benzylic sp<sup>3</sup> C–H bonds using catalytic 1,4-hydroquinone, or its biorenewable glucoside, arbutin, as a pre-oxidant
作者:Laura C. Finney、Lorna J. Mitchell、Christopher J. Moody
DOI:10.1039/c7gc03741d
日期:——
a sustainable alternative for the late stage oxidative functionalization of benzylic C–H bonds. It is applicable to a range of cyclic benzylic ethers such as isochromans and phthalans, and simple benzyl alkyl ethers. It can also be applied in the oxidation of benzylic amines into amides, and of diarylmethanes into the corresponding ketones. Mechanistic studies suggest that the reaction proceeds by
苯甲醚经过可见光诱导的C–H活化和氧的插入,以中等至良好的产率得到相应的苯甲酸酯。该条件采用亚化学计量的1,4-氢醌与氯化铜(II)二水合物作为电子转移介体,氧气作为末端氧化剂,碳酸二甲酯作为溶剂在可见光照射下。天然存在的糖苷,熊果苷,可商购获得,或可通过提取熊果(Arctostaphylos uva-ursi)或象耳(Bergenia crassifolia)的叶子获得)可以用作1,4-对苯二酚的生物可再生来源。该方法利用了可见光照射后醌氧化能力的提高,并为苄基CH键的后期氧化官能化提供了一种可持续的替代方法。它适用于各种环状苄基醚,例如异色满和酞菁,以及简单的苄基烷基醚。它也可用于将苄基胺氧化为酰胺,并将二芳基甲烷氧化为相应的酮。机理研究表明,该反应通过光激发的三重态苯并醌进行H吸收来进行,从而产生一个苄基,该苄基随后与分子氧反应。