A novel CAN‐SiO2‐mediated one‐pot oxidation of 1‐keto‐1,2,3,4‐tetrahydrocarbazoles to carbazoloquinones: Efficient syntheses of murrayaquinone A and koeniginequinone A |
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Authors: | Suchandra Chakraborty Gautam Chattopadhyay Chandan Saha |
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Affiliation: | 1. Department of Clinical and Experimental Pharmacology, School of Tropical Medicine, Kolkata 700073, India;2. Postgraduate Department of Chemistry, Presidency College, Kolkata 700073, India |
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Abstract: | One‐pot oxidations of substituted 1‐keto‐1,2,3,4‐tetrahydrocarbazoles ( 1 ) to carbazole‐1,4‐quinones ( 2 ) are efficiently carried out by CAN‐SiO2‐mediated reaction. This generalized protocol was successfully extended to the synthesis of two naturally occurring carbazoloquinones: murrayaquinone A ( 2b ) and koeniginequinone A ( 2g ). A plausible mechanism for this novel reaction involves formation of a 9‐hydroxy‐2,3,4,9‐tetrahydro‐1H‐carbazole‐1‐one followed by rearrangement to 1‐hydroxycarbazole derivatives, which are further oxidized by cerium (IV) to carbazoloquinones. J. Heterocyclic Chem., (2011). |
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