Aromatic Thioesters as Protecting Groups for Thiols Against 1,2‐Didehydrobenzenes

Divalent sulfur compounds usually react with 1,2‐didehydrobenzenes to give a palette of unspecific products. To identify a suitable protecting group for thiols under the reaction conditions typically used for the synthesis of triptycenes, that is, 1,2‐didehydrobenzene generated in situ from 2‐diazoniobenzenecarboxylate at elevated temperatures, a wide‐ranging optimization study was conducted. Of several acyl groups investigated, the benzoyl group turned out to be optimal. The efficiency of this protecting group was demonstrated by the successful transformation of an electron‐poor (thus unreactive) anthracene derivative to the corresponding triptycenethiol derivative. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)