Electrochemical Dearomative Spirocyclization of N-Acyl Thiophene-2-sulfonamides.

The Friedel-Crafts type alkylation of C2-tethered thiophenes has been reported to be nonregioselective. Taking advantage of the highly regioselective 5-exo-trig spirocyclization of an electrochemically generated amidyl radical, we have unraveled an electrochemical dearomative spirocyclization of N-acyl thiophene-2-sulfonamides. Various nucleophilic agents, including carboxylates, alcohols, and fluoride, are readily incorporated to afford the remotely functionalized spirocyclic dihydrothiophenes, and their novel spirocyclic scaffolds have been shown to exhibit promising antitumor activities.