Methanesulfonyl chloride, halogenation

Direct halogenation of sucrose has also been achieved using a combination of DMF—methanesulfonyl chloride (88), sulfuryl chloride—pyridine (89), carbon tetrachloride—triphenylphosphine—pyridine (90), and thionyl chloride—pyridine—1,1,2-trichloroethane (91). Treatment of sucrose with carbon tetrachloride—triphenylphosphine—pyridine at 70°C for 2 h gave 6,6 -dichloro-6,6 -dideoxysucrose in 92% yield. The greater reactivity of the 6 and 6 primary hydroxyl groups has been associated with a bulky halogenating complex formed from triphenylphosphine dihaUde ((CgH )2P=CX2) and pyridine (90). 

The oxygen atom at 21 is similarly an expendable group. Reaction of 241 (obtained from 185 by the usual procedure for introduction of the 9a-fluoro group) with methanesulfonyl chloride affords the 21 mesylate (242a). Replacement of the leaving group at 21 with iodine by means of potassium iodide in acetone followed by reduction of the halogen with zinc in acetic acid leads to fluorometholone (243). ... 

The reaction of Af,Af-dimethyl-( )-styrylamine (73) with a halogen-substituted methanesulfonyl chloride allowed the first stereoselective formation of the halogenated thietane 1,1-dioxide 74, which then could be converted to the corresponding thiete sulfone 75 via a Cope elimination of the corresponding AT-oxide. ... 

Substitution of fluorine for halogen in aromatic and alkyl sulfonyl halides can be carried out with or without using a solvent. An aqueous system such as 70 % aqueous potassium fluoride is also used because the rate of hydrolysis is much slower than the rate of fluorination as reported for the conversion of methanesulfonyl chloride (1) to methanesulfonyl fluoride (2).23... 

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