Cu-Mn spinel oxide catalyzed regioselective halogenation of phenols and N-heteroarenes.
A novel simple, mild chemo- and regioselective method has been developed for the halogenation of phenols using Cu-Mn spinel oxide as a catalyst and N-halosuccinimide as halogenating agent. In the presence of Cu-Mn spinel oxide B, both electron-withdrawing and electron-donating groups bearing phenols gave monohalogenated products in good to excellent yields with highest para-selectivity. The para-substituted phenol gave monohalogenated product with good yield and ortho-selectivity. N-Heteroarenes such as indoles and imidazoles also gave monohalogenated products with high selectivity. Unlike the copper-catalyzed halogenation, the present method works well with electron-withdrawing group bearing phenols and gives comparatively better yields and selectivity. The Cu-Mn spinel catalyst is robust and reused three times under optimized conditions without any loss in catalytic activity. Nonphenolics did not undergo this transformation.
Medicinal Chemistry Division, Indian Institute of Integrative Medicine (Council of Scientific & Industrial Research), Jammu 180 001, India. ppsingh@iiim.res.in
Parvinder Pal
PP
Singh
Thanusha
T
Thatikonda
K A Aravinda
KA
Kumar
Sanghapal D
SD
Sawant
Baldev
B
Singh
Amit Kumar
AK
Sharma
P R
PR
Sharma
Deepika
D
Singh
Ram A
RA
Vishwakarma
D001974:Bromosuccinimide / Q000737:chemistry; D002384:Catalysis; D003300:Copper / Q000737:chemistry*; D054879:Halogenation; D006571:Heterocyclic Compounds / Q000737:chemistry*; D006846:Hydrocarbons, Halogenated / Q000138:chemical synthesis / Q000737:chemistry; D008345:Manganese / Q000737:chemistry*; D015394:Molecular Structure; D010087:Oxides / Q000737:chemistry*; D010636:Phenols / Q000737:chemistry*; D013237:Stereoisomerism; D013388:Succinimides / Q000737:chemistry
D006571:Heterocyclic Compounds; D006846:Hydrocarbons, Halogenated; D010087:Oxides; D010636:Phenols; D013388:Succinimides; C015752:N-chlorosuccinimide; D008345:Manganese; D003300:Copper; D001974:Bromosuccinimide