Benzimidazole with sulfuryl chloride

Benzimidazole 3-oxides, e.g. (189), react with phosphorus oxychloride or sulfuryl chloride to form the corresponding 2-chlorobenzimidazoles. The reaction sequence involves first formation of a nucleophilic complex (190), then attack of chloride ions on the complex, followed by rearomatization involving loss of the fV-oxide oxygen (191 -> 192). 

Benzimidazole 3-oxides, e.g., 276, react with phosphorus oxychloride or sulfuryl chloride to form the corresponding... 

One of the amino functions in o-phenylenediamine can be functionalized in other ways. Thus high yields of polychlorobenzimidazoles (9) are formed when sulfuryl chloride reacts with o-amino-iV,iV-dialkylanilines, while the Schiff base (10) eliminates methanol when it cyclizes to the 2-substituted benzimidazole (Scheme 5) (75MI40800). 

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