Electrochemical oxidative dearomatization of 2-arylthiophenes

Abstract

Herein we report a green and sustainable electrochemical oxidative dearomatization of 2-arylthiophenes. The variation of substitution patterns affords easy access toward both the C2/C3 and C2/C5 difunctionalized dearomative products. The...

Application of Metal‐Free Dearomatization Reaction as a Sustainable Strategy to Direct Access Complex Cyclic Compounds

“…They discovered that the C2 position of thiophenes 122 is more dynamic than the C3 position to accomplish the electrochemical oxidative dearomatization, affording a wide array of C2/C5 difunctionalized 2‐arylthiophines 123 and C2/C3 difunctionalized products 124 by changing the substitution patterns (Scheme 48). [58] These electrochemical oxidative methods would complement previous approaches and support expansion of the toolbox for the dearomatization of aromatic compounds. We believe it will be sustainable research in the future.…”

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

“…Among various aromatics − and heteroaromatics, , the dearomative spirocyclization of thiophenes is underdeveloped, probably due to their relatively high resonance stabilization energy (∼22 kcal mol –1 ). − For instance, Wright and co-workers have shown that the electrochemical dearomative spirocyclization of the C2-tethered furan readily proceeded with C2-spirocyclization (Scheme A) . When it is transferred to the analogous thiophene derivative, however, a nonselective C2 and C3 Friedel–Crafts type alkylation took place, followed by downstream chemical and electrochemical transformations, to generate both C3-annulation and C2-spirocyclization products.…”

“…Notably, the incorporation of an extra bromo group into the thiophene moiety ( 39 ) readily afforded the dearomative thiophenone ( 40 ), probably via the hydrolysis of a dihydrothiophene diacetate intermediate (Scheme , eq 1). , The ( p -tolyl)­acetic acid derivative ( 41 ), however, did not proceed with the electrochemical dearomative spicrocyclization but gave the oxindole scaffold ( 42 ), likely via a sequential electrochemical ortho amination and benzylic oxygenation (eq 2). The thiophenone ( 40 ) and oxindole ( 42 ) products were both confirmed by X-ray crystallographic analyses…”