Cu-Mn spinel oxide catalyzed regioselective halogenation of phenols and N-heteroarenes |
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Authors: | Singh Parvinder Pal Thatikonda Thanusha Kumar K A Aravinda Sawant Sanghapal D Singh Baldev Sharma Amit Kumar Sharma P R Singh Deepika Vishwakarma Ram A |
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Institution: | Medicinal Chemistry Division, Indian Institute of Integrative Medicine (Council of Scientific & Industrial Research), Jammu 180 001, India. ppsingh@iiim.res.in |
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Abstract: | 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. |
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