Development of efficient new methodology for generation, cyclization and functional trapping of iminyl and amidyl radicals

New methodology has been devised for the generation and subsequent cyclization of iminyl and amidyl radicals under mild conditions. The process involves either the treatment of oximes with 2,6-dimethylbenzenesulfinyl chloride, or the treatment of hydroxamic acids with tert-butylsulfinyl chloride (−50°C to rt), to give the corresponding nitrogen radicals, followed by cyclization onto pendant olefins. Radical traps such as diphenyl diselenide, diphenyl disulfide, and TEMPO can be used to terminate the cyclizations, thus introducing functionality that provides multiple options for further manipulation. In a more convenient procedure, both iminyl and amidyl radical cyclizations can be initiated using commercially available diethyl chlorophosphite which generally provides similar (with diphenyl disulfide and TEMPO) or significantly higher (with diphenyl diselenide) yields of products.