Visible Light-promoted β-CH Halogenation Of Amide

Amide has important applications in pharmaceutical chemistry,organic synthesis and so on.Among them,β-halogenamide is the structural unit of many drugs and pesticides and an important intermediate in organic synthesis.C-H bond activation is an important method for direct modification of organic molecules.β-C-H halogenation is one of the effective methods for synthesis of β-halogenated amides because of its atomic economy and step economy.In recent years,organic synthetic chemists have developed a series of amide β-C-H halogenation reactions.These reactions often require the use of palladium catalysts,acidic additives,and oxidants.Therefore,it is urgent to develop a β-C-H halogenation reaction with mild conditions and cheap catalyst.Combination of a ligand-to-metal charge transfer(LMCT)and 1,4-hydrogen atom transfer(1,4-HAT)is employed.The visible light promoted the chlorination of amide and its derivative β-C(sp3)-H using NCS and more atom economic HCl as halogen source and CuCl2 as catalyst.The method is suitable for aromatic amine derivatives of secondary and tertiary carboxylic acids.Mild reaction conditions enabled halogenation of complex medicinal derivatives possible.