Conversion of Anilines into 2-Aminobenzo-thiazoles via Herz Compounds

Significance

Reported is the synthesis of 2-aminobenzothiazoles in three steps from anilines. Anilines were first converted into Herz compounds using established Herz conditions and then hydrolyzed to the corresponding sulfoxides. These then underwent reaction with various isocyanates in the presence of catalytic iodine to give the amino­thiazole products. Attempted reaction of the sulf­oxide and isocyanates with no additive, or with Lewis acids such as Sc(OTf)₃ was unsuccessful. Molecular iodine was selected as a potential catalyst due to its dual Lewis acid/oxidant character and also due to its known high reactivity with dithianes. A mechanism was proposed and discussed, but without evidence.