Oxidative Cyclization of Sulfamate Esters Using NaOCl - A Metal-Mediated Hoffman-Löffler Freytag Reaction

Intramolecular C-H amination with sulfamate esters occurs under the action of dinuclear Rh catalysts and iodine(III) oxidants, and has recently emerged as a powerful tool for synthesis. Insights gained through mechanistic studies of this process suggest that other terminal oxidants, including common halogenating agents such as NaOCl, could function to promote the cyclization reaction. Results described in this report demonstrate that the combination of NaOCl and 3 mol% Rh(2)(oct)(4) is effective in select cases for converting sulfamate substrates to the corresponding [1,2,3]-oxathiazinane-2,2-dioxide heterocycles. The mechanism for C-H functionalization, however, is distinct from that induced by hypervalent iodine reagents and likely involves the intermediacy of an N-centered radical.