Catalyst-free direct cross-dehydrogenative coupling of imidazoheterocycles with glyoxal hydrates: an efficient approach to 1,2-diketones.

An efficient and convenient methodology for catalyst-free cross-dehydrogenative coupling of imidazoheterocycles with glyoxal hydrates in good yields was developed. This methodology exhibits a broad substrate scope and excellent functional group tolerance and offers a straightforward means to produce different heterocycles such as imidazoheterocyclic quinoxaline, imidazoheterocyclic hydantoin and imidazoheterocyclic α-keto ketamine under relatively mild conditions. Biological evaluation showed that the most potent compound 3m possesses significant in vitro antiproliferative activities against human-derived lung cancer cell lines with an IC50 value of 14.8 µM.

Copper-catalyzed C-H/N-H cross-coupling reactions for the synthesis of 3-heteroaryl quinoxalin-2(1H)-ones.

An effective copper-catalyzed direct C-H/N-H cross-coupling of quinoxalin-2(1H)-ones with diverse unprotected 2-quinoxalinones and 2-quinolinones has been developed. This protocol provides a convenient route, with broad substrate scope, good functional group tolerance, and high atom economy, to various important quinoxalin-2(1H)-one-containing biheteroaryls, which are privileged structures in many biologically active compounds.