Department of Chemistry, University of Helsinki , A.I. Virtasen aukio 1, 00014 Helsinki, Finland.
J Org Chem. 2017 Dec 15;82(24):13756-13767. doi: 10.1021/acs.joc.7b02775. Epub 2017 Nov 27.
Facile photoreductive protocols have been developed to remove benzyl O-protective groups from oxyarene N-heterocycles at positions capable for 2-/4-O-pyridine-2-/4-pyridone tautomerism. Blue light irradiation, a [Ru] or [Ir] photocatalyst, and ascorbic acid in a water-acetonitrile solution debenzylates a variety of aryl N-heterocycles cleanly and selectively. Ascorbic acid has two functions in the reaction. On the one hand, it protonates the N-heterocycles that reduces their reduction potentials notably and on the other hand it acts as a sacrificial reductant. Reduction potentials and free energy barriers calculated at the CPCM-B3LYP/6-31+G** level can predict the reactivities of the studied substrates.
已经开发出了简便的光还原方法，可将位置适合 2-/4-氧代吡啶-2-/4-吡酮互变异构的氧杂芳烃 N-杂环上的苄基 O-保护基团除去。在水-乙腈溶液中，使用蓝光照射、[Ru]或[Ir]光催化剂和抗坏血酸，可以将各种芳基 N-杂环化合物清洁且选择性地脱苄基化。抗坏血酸在反应中有两个作用。一方面，它使 N-杂环质子化，从而显著降低其还原电位；另一方面，它作为牺牲还原剂。在 CPCM-B3LYP/6-31+G**水平下计算的还原电位和自由能垒可以预测研究底物的反应性。
