Difluoro-λ3-bromane-Induced Hofmann Rearrangement of Sulfonamides: Synthesis of Sulfamoyl Fluorides
Difluoro-λ3-bromane-Induced Hofmann Rearrangement of Sulfonamides: Synthesis of Sulfamoyl Fluorides
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DOI：
10.1021/ja903544d
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发表时间：
2009-06-24
影响因子：
15
通讯作者：
Shiro, Motoo
中科院分区：
文献类型：
--
作者：
Ochiai, Masahito;Okada, Takuya;Shiro, Motoo
我们报道了伯芳烃磺酰胺的Hofmann重排反应的第一个例子，它依赖于对三氟甲基苯基（二氟）-λ（3）-溴烷的使用，并在室温下选择性地得到N-芳基氨磺酰氟。芳基-λ（3）-碘烷与对甲苯磺酰胺反应得到磺酰基单-λ（3）-碘烷，它是生成类金属氮杂环戊烯物种的优良母体。与此形成鲜明对比的是，二氟-λ（3）-溴烷与对甲苯磺酰胺在苯中的反应通过霍夫曼重排以高产率产生独特的N-对甲苯基氨磺酰氟。具有给电子取代基（p-MeO和o-Me）和吸电子取代基（p-F、p-Cl和p-CF 3）的芳磺酰胺有效地进行λ（3）-溴烷诱导的Hofmann重排。用单晶X射线衍射法测定了N-对甲苯基氨磺酰氟的结构。芳基-λ（3）-碘代基和芳基-λ（3）-溴代基之间的离核性差异，后者更大，可能在决定反应过程中起关键作用。从2，3，5，6-四甲基苯磺酰胺的反应中得到的结果强烈地表明，磺酰基氮烯的生成不会参与该重排。
We report the first example of Hofmann rearrangement of primary arenesulfonamides, which relies on the use of p-trifluoromethylphenyl(difluoro)-lambda(3)-bromane and affords N-arylsulfamoyl fluorides selectively at room temperature. Reaction of aryl-lambda(3)-iodanes with p-toluenesulfonamide affords sulfonylimono-lambda(3)-iodanes, being excellent progenitors for generation of metal-nitrenoid species. In marked contrast, reaction of the difluoro-lambda(3)-bromane with p-toluenesulfonamide in benzene produced unique N-p-tolytsulfamoyl 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 lambda(3)-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-lambda(3)-iodanyl and aryl-lambda(3)-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.