Dehydrogenative Electrochemical Synthesis of N‐Aryl‐3,4‐Dihydroquinolin‐2‐ones by Iodine(III)‐Mediated Coupling Reaction

Abstract

Electrochemically generated hypervalent iodine(III) species are powerful reagents for oxidative C−N coupling reactions, providing access to valuable N‐heterocycles. A new electrocatalytic hypervalent iodine(III)‐mediated in‐cell synthesis of 1H‐N‐aryl‐3,4‐dihydroquinolin‐2‐ones by dehydrogenative C−N bond formation is presented. Catalytic amounts of the redox mediator, a low supporting electrolyte concentration and recycling of the solvent used make this method a sustainable alternative to electrochemical ex‐cell or conventional approaches. Furthermore, inexpensive, readily available electrode materials and a simple galvanostatic set‐up are applied. The broad functional group tolerance could be demonstrated by synthesizing 23 examples in yields up to 96 %, with one reaction being performed on a 10‐fold higher scale. Based on the obtained results a sound reaction mechanism could be proposed.

Efficient and Sustainable Electrosynthesis of N-Sulfonyl Iminophosphoranes by the Dehydrogenative P–N Coupling Reaction

“…Sulfanilamide, which was formerly used as an antibiotic, yielded 16 in 45% yield. Pleasingly, the unprotected amino group was tolerated in the reaction, which tends to be challenging under oxidative conditions. − Moreover, redox-sensitive nitro groups were tolerated in the reaction, as is evident from 17 , which was isolated in a 25% yield. Benzenesulfonamide with an unsubstituted phenyl group yielded 18 in 81%.…”