Efficiency and Selectivity Aspects in the C-H Functionalization of Aliphatic Oxygen Heterocycles by Photocatalytic Hydrogen Atom Transfer
Efficiency and Selectivity Aspects in the C-H Functionalization of Aliphatic Oxygen Heterocycles by Photocatalytic Hydrogen Atom Transfer
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DOI：
10.1055/s-0037-1612079
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发表时间：
2019-04-01
期刊：
影响因子：
2
通讯作者：
Ravelli, Davide
中科院分区：
文献类型：
--
作者：
Raviola, Carlotta;Ravelli, Davide
通过光催化氢原子转移和随后用苯基乙烯基砜捕获所得自由基，研究了脂肪族氧杂环（二氧戊环、1,3-二恶烷或环状碳酸酯）中的 C-H 到 C-C 的转化。比较了三种不同光催化剂（即十钨酸四丁基铵和芳香酮噻吨酮和9-芴酮）的性能。尽管酮可以被可见光激发，但是吸收紫外线的十钨酸根阴离子比芳香酮更有效并且允许使用更少量过量的氢供体。进一步的分子内选择性研究表明，与十钨酸根阴离子相比，芳香酮在缩醛位置和醚位置上提供了更高比例的官能化。
The C-H to C-C conversion in aliphatic oxygen heterocycles (dioxolanes, 1,3-dioxane, or cyclic carbonates) by photocatalytic hydrogen atom transfer and subsequent trapping of the resulting radical with phenyl vinyl sulfone was investigated. The performance of three different photocatalysts, namely tetrabutylammonium decatungstate and the aromatic ketones thioxanthone and 9-fluorenone, was compared. The UV-light-absorbing decatungstate anion is more efficient and permits the use of a smaller excess of hydrogen donor than the aromatic ketones, although the ketones could be excited by visible light. Further intramolecular selectivity studies revealed that aromatic ketones afforded a higher proportion of functionalization at the acetalic versus the ethereal positions than did the decatungstate anion.