Room-temperature chromium(II)-catalyzed direct arylation of pyridines, aryl oxazolines, and imines using arylmagnesium reagents

Org Lett. 2014 Oct 3;16(19):5208-11. doi: 10.1021/ol502623v. Epub 2014 Sep 17.

Abstract

We report a CrCl2-catalyzed oxidative arylation of various pyridines, aryl oxazolines, and aryl imines using aromatic Grignard reagents in the presence of 2,3-dichlorobutane (DCB). Most of the reactions proceed rapidly at 25 °C and do not require any additional ligand. Benzo[h]quinoline, 2-arylpyridine, aryl oxazoline, and imines were successfully arylated in good yields under these conditions. A TMS-substituent was used to prevent double arylation. After oxidative cross-coupling the TMS-group was further converted to a second ortho-aryl substituent. Remarkably, inexpensive aryl N-butylimine derivatives are excellent substrates for this oxidative arylation.