PREPARATIVE HAZARDS Sulfur dioxide

Tetrafluorooxathietane-2,2-dioxide (Tetrafluoroethane sultone) [697-18-7] o / I 2c,, so2 cf2 Preparative hazard See Sulfur trioxide Tetralluoroethylene C2F403S... 

Preparative hazard See Diethylzinc Sulfur dioxide See related SULFUR ESTERS C4Hio04S2Zn Zn[0S( 0)Et]2... 

Preparative hazard See Nitric acid Sulfur dioxide... 

In summary, sulfonamides are most commonly prepared by the reaction of amines with sulfonyl halides. Aryl sulfonyl chlorides may be accessed from C-H bonds by chlorosulfonylation, from C-S bonds by oxidation, from C-N bonds by diazotization, or from C-X bonds by metalation. Approaches to all l sulfonamides are more limited as they are typically prepared by either oxidative chlorination of thiols or addition of organometallic nucleophiles to sulfur electrophiles. Traditional sulfonamide preparation has frequently necessitated harsh reagents and conditions, but the development of Pd-catalysed approaches and discovery of new sulfur dioxide sources allow for operationally simple sulfonamide synthesis under mild conditions. Future directions in sulfonamide synthesis will likely involve the direct C-H installation of sulfonamides without the use of hazardous reagents. 

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