Dicyclopentyl Dithiosquarate as an Intermediate for the Synthesis of Thiosquaramides.

A general and greatly improved route is reported for the synthesis of a variety of thiosquaramides from a common dithionated intermediate. Both diaryl thiosquaramides and bifunctional thiosquaramides are readily accessed from dicyclopentyl dithiosquarate via two addition-elimination reactions. The convenient handling characteristics and relative stability of associated intermediates enable an operationally simple thiosquaramide preparation. Bifunctional aryl thiosquaramides, which were inaccessible by the previous method, are also prepared, and their catalytic performance is demonstrated, including their capability to function as Brønsted acid catalysts.