Hofmann Rearrangement of Carboxamides

The first catalytic version of the Hofmann rearrangement using aryl iodides as catalysts and mCPBA as terminal oxidant was reported by Ochiai and coworkers in 2012 [72], A study of the catalytic efficiency of substituted iodobenzenes and some aliphatic alkyl iodides in the iodane(III) catalyzed Hofmann rearrangement of benzylic carboxamides has demonstrated that iodobenzene is the best catalyst. The introduction of both electron-donating (4-methyl, 3,5-dimethyl and 2,4,6-trimethyl) and electron-withdrawing groups (4-Cl and 4-CF3) into iodobenzene decreased the yield of rearranged products. Aliphatic iodides such as methyl, trifluoroethyl and 1-adamantyl iodides showed no catalytic efficiency. Under optimized reaction conditions, 

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Hydroxy)phenyl-X -iodane complex 78 promotes the Hofmann rearrangement of carboxamides 74, probably via intermediate formation of Ai-(phenyliodanyl)carboxamides 79 [72],... 

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