A practical, electrochemical method is developed for the direct dehydrogenative lactonization of C(sp2/sp3)–H bonds under external oxidant- and metal-free conditions, delivering diverse lactones, including coumarin derivatives with excellent regioselectivity. The scalable nature of this newly developed electrochemical process was demonstrated on a 40 g scale following an operationally simple protocol
Oxidant-Free C(sp<sup>2</sup>)–H Functionalization/C–O Bond Formation: A Kolbe Oxidative Cyclization Process
作者:Lei Zhang、Zhenxing Zhang、Junting Hong、Jian Yu、Jianning Zhang、Fanyang Mo
DOI:10.1021/acs.joc.8b00089
日期:2018.3.16
An anodic oxidation/cyclization of 2-arylbenzoic acids for the synthesis of dibenzopyranones has been developed. The reaction proceeds at room temperature with no oxidant or electrolyte required and exhibits a high atom economy with H-2 being the only byproduct. A series of dibenzopyranones was obtained in good to excellent yields. Urolithins A, B, and C are formally synthesized by adopting this method as a key step to demonstrate its synthetic utility.