Copper-Mediated Remote Highly Site-Selective C-H Bond Bromination and Chlorination of Quinolines at the C5 Position that is Geometrically Difficult to Access
Abstract: We report a concise and efficient method for the remoteC-Hbond halogenation (Br & Cl) of 8-aminoquinoline scaffolds on the C5position that is geometricallydifficult to access. The protocol makes use of inexpensive CuBr2 and CuCl2 as a mediator and shows good tolerance toward numerous N-(8-quinolinyl)-benzamides, giving the corresponding products in good to excellent yield.
C5 position was described. The reaction utilized easily available sodiumhalides as the halogen sources and proceeded smoothly under transition metal-free conditions. Various 8-aminoquinolines with a number of functional groups were compatible in this reaction to afford the corresponding halogenated products in moderate to good yields. Moreover, the reactionconditions also tolerated the substrates
An efficient and convenient method for remote C5 halogenation of 8-aminoquinoline derivatives was developed in continuous flow at room temperature. This method employed inexpensive 1,3-dibromo-5,5-dimethylhydantoin (DBDMH) and 1,3-dichlro-5,5-dimethylhydantoin (DCDMH) as halogenation reagents and visible light to catalyze the reaction. The reaction is scalable to gram-scale and proceeded with air and moisture tolerance, good functional group compatibility, and outstanding site selectivity, providing a new pathway for C5 halogenation of 8-aminoquinolines. (C) 2019 Published by Elsevier Ltd.