Electrochemical Dearomatization: Evolution from Chemicals to Traceless Electrons

Abstract

Dearomatizationr eactions represent av ersatile approach for the preparation of three-dimensionally (3D) privileged cyclic moieties from simple planar aromatic compounds.H owever, exogeneous oxidants are required for most of the radical ando xidative dearomatizations.T herefore,s ustainable proceduresa re in high demand, especially those in the absence of external oxidizing reagents.F ortunately, electrolytic dearomatization protocols can fulfill the abover equirements due to the manipulation of traceless electrons insteado fc hemicals during the processes. Nevertheless,s ustainable electrochemical dearomative transformationsh ave been farl ess frequently investigated than the well-developed chemical dearomatizationr eactions.H erein, we summarize representativeb reakthroughs in the electrochemical dearomative transformation of indoles,f urans and activated arenes (phenols anda nisoles) for the synthesis of complicated skeletons.H opefully,t his interesting "simplicity-to-complexity" synthetic logic will inspire more innovations from the electroorganic community.Scheme 28. Electrochemical dearomatizationo fthe phenylpropenoid system for generating quinone methide dimers.

Tunable Electrochemical C−N versus N−N Bond Formation of Nitrogen‐Centered Radicals Enabled by Dehydrogenative Dearomatization: Biological Applications

“…Considering the intriguing structure of pyridine, both the captodative effect and the delocalization effect might be achieved in one molecule. Interestingly, dearomatization of the pyridine motif can effectively proceed under electrolytic conditions . The aforementioned meaningful discoveries promoted us to question whether a tunable behavior of species C could be achieved through the dearomative strategy (Scheme a, C ).…”

Dearomatization Reactions of Indoles to Access 3D Indoline Structures

“…40 The selective difunctionalization of alkenes is an important application of electrochemistry, 41 yet he related electrochemical dearomatization has been less studied. 42 As mentioned above, in 2017 Lei and co-workers deployed electrochemistry to improve our oxidative coupling between N-Ac indoles and phenols (Scheme 10). 21 In this transformation, the N-Ac indole is considered to be oxidized at the anode into a radical cation.…”

Electrochemical Dearomative Dihydroxylation and Hydroxycyclization of Indoles

“…[2] The related electrochemical dearomative 1,2-difunctionalization of (hetero)arenes and in particular indoles has been less studied. [3][4][5][6][7][8] The dearomatization of indole, for which we have been interested for almost a decade, [9,10] generates three dimensional indolines of potential biological relevance. [11] In few cases, dearomative electrolysis could be performed from an NÀ H indole substrate [6] as it was demonstrated by Harran during the 60 gram-scale synthesis of the benzofuroindoline core of DZ-2384, a highly potent antitumoral agent inspired by the natural product diazonamide A.…”