Difluoro-λ3-bromane-induced hofmann rearrangement of sulfonamides: Synthesis of sulfamoyl fluorides

Masahito Ochiai, Takuya Okada, Norihiro Tada, Akira Yoshimura, Kazunori Miyamoto, Motoo Shiro

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Abstract

(Chemical Equation Presented) We report the first example of Hofmann rearrangement of primary arenesulfonamides, which relies on the use of p-trifluoromethylphenyl(difluoro)-λ3-bromane and affords N-arylsulfamoyl fluorides selectively at room temperature. Reaction of aryl-λ3-iodanes with p-toluenesulfonamide affords sulfonylimono-λ3-iodanes, being excellent progenitors for generation of metal-nitrenoid species. In marked contrast, reaction of the difluoro-λ3-bromane with p-toluenesulfonamide in benzene produced unique N-p-tolylsulfamoyl fluoride in a high yield, through Hofmann rearrangement. Arenesulfonamides with electron-donating (p-MeO and o-Me) and -withdrawing substituents (p-F, p-Cl, and p-CF3) efficiently undergoes the λ3-bromane-induced Hofmann rearrangement. The structure of N-p-tolylsulfamoyl fluoride was determined by a single-crystal X-ray analysis. The differences in nucleofugality between aryl- λ3-iodanyl and aryl-λ3-bromanyl groups, the later being greater, probably play a pivotal role in determining the reaction course. The results obtained from the reaction of 2,3,5,6- tetramethylbenzenesulfonamide strongly suggest that generation of sulfonyl nitrene will not be involved in this rearrangement.

Original languageEnglish (US)
Pages (from-to)8392-8393
Number of pages2
JournalJournal of the American Chemical Society
Volume131
Issue number24
DOIs
StatePublished - Jun 24 2009
Externally publishedYes

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