Cu-Catalyzed Heteroannulation Route to 2-Iminobenzo-1,3-oxathioles

Significance

An efficient synthesis of 2-imino­benzo-1,3-oxathioles from simple precursors, o-iodophenols and isothiocyanates, via a Cu-­catalyzed one-pot heteronannulation process is reported. Conditions were optimized by extensive studies in variation of solvent, copper source and ligand. Yields are generally high with only 1-iodo-2-naphthol failing to react, possibly due to steric hindrance, and a 2,6-diiodophenol affording a complex mixture. Substrate scope was well studied, and both aryl and alkyl isothiocyanates were shown to undergo the heteroannulation reaction, albeit the latter requiring longer reaction times.