Use of thiazyl chlorides, alkyl carbamates, and thionyl chloride to fuse 1,2,5-thiadiazoles to quinones and to oxidize, chlorinate, and aminate them

Article abstract of DOI:10.1021/jo00110a036

Thiazyl chlorides in a simple one-step procedure fuse 1,2,5-thiadiazole rings to quinones. So do alkyl carbamates mixed with excess thionyl chloride and pyridine. Evidence is put forward to support the hypothesis that NSCl or a related thiazyl derivative is the reactive species that brings about the transformations. Selenoyl chloride mixed with an alkyl carbamate, pyridine, and quinones similarly gives 1,2,5-selenodiazoloquinones. Thionyl chloride in pyridine chlorinates quinones and oxidizes hydroquinones. 2,3-Dichloro-1,4-quinones with S₄N₄ or with alkyl N-sulfinylcarbamates give 1,2,5-thiadiazoloquinones. Quinones and their 2,3-dichloro derivatives with TsNSO in pyridine give betaine derivatives of 2,3-diaminoquinones, which pyrrolidine converts into 2-amino-3-(tosylamino)quinones. A unified set of mechanisms is presented that accounts for these transformations.