Neighboring Group Participation in the Halogenation of Sulfoxides

Abstract

PhS(O)(CH2)nCH2OH(n = 1–3) react with sulfuryl chloride at −78° or 0° in methylene chloride to give the corresponding PhSO2(CH2)nCH2Cl. Evidence is presented that cyclic alkoxyoxosulfonium salts are intermediates in these transformations. When n = 4 only chlorination α to the sulfoxide function was observed. The sulfinyl carboxylic acids PhS(O)(CH2)nCO2H (n = 1–3) and amides PhS(O)(CH2)nCONH2 (n = 1–3) were also reacted with SO2Cl2. α-Chlorination was observed for both compounds when n = 1 or 3. When n = 2 the products were the 3-phenylsulfonylpropionyl chloride and 3-phenyl-sulfonylpropionitrile respectively.