Zhuang Yan-Jun, Qu Jian-Ping, Kang Yan-Biao
Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026, China.
Institute of Advanced Synthesis, School of Chemistry and Molecular Engineering, Nanjing Tech University, Nanjing 211816, China.
J Org Chem. 2020 Mar 20;85(6):4386-4397. doi: 10.1021/acs.joc.0c00102. Epub 2020 Feb 25.
Salicylaldehyde is established as an efficient visible light photocatalyst for the first time. Compared to other simple aldehyde analogies, salicylaldehyde has a unique deprotonative red-shift from 324 to 417 nm and gives rise to the remarkable increase of fluorescence quantum from 0.0368 to 0.4632, thus enabling salicylaldehyde as a visible light (>400 nm) photocatalyst. The experimental investigations suggest that the reactive radical species are generated by sensitization of the substrates by the deprotonated salicylaldehyde through an energy-transfer pathway. Consequently, the C-C cleaving alkylation reactions of -hydroxyphthalimide esters proceed smoothly in the presence of as low as 1 mol % of salicylaldehyde under the visible-light irradiation, affording desired alkylation products with up to 99% yields. Application in visible-light induced aerobic oxidation of -alkylpyridinium salts is also reported.
水杨醛首次被确立为一种高效的可见光光催化剂。与其他简单的醛类似物相比，水杨醛具有独特的去质子化红移，从324纳米移至417纳米，并使荧光量子显著增加，从0.0368增至0.4632，从而使水杨醛成为一种可见光（>400纳米）光催化剂。实验研究表明，反应性自由基物种是通过去质子化水杨醛对底物的敏化作用，经由能量转移途径产生的。因此，在可见光照射下，在低至1摩尔%的水杨醛存在下，邻羟基苯二甲酰亚胺酯的C-C键断裂烷基化反应顺利进行，可提供产率高达99%的所需烷基化产物。还报道了其在可见光诱导的α-烷基吡啶盐需氧氧化中的应用。
