Progress in Organocatalytic Dearomatization Reactions Catalyzed by N‐Heterocyclic Carbenes

Abstract

intermediates, homoenolate intermediates, enolate intermediates, and azolium dienolate intermediates), NHCs can readily destroy aromaticity by electrophilic or nucleophilic interactions with aromatic compounds. In this overview, progress in NHCcatalyzed dearomative reactions is summarized; the reactions are grouped according to reaction modes and categories of intermediates, and representative mechanisms are provided. This review aims to serve as a comprehensive reference for work in the emerging field of organocatalytic dearomatization.

Asymmetric Substitution by Alkynyl Copper Driven Dearomatization and Rearomatization

“…The absolute configuration of 5 p was also elucidated via X-ray crystallography analysis. Moreover, a set of downstream transformations from 5 p was studied, and the alkynyl unit was easily transformed into various moieties, such as isoxazole, vinylphosphine oxide, and indole moieties (8)(9)(10). The saccharide molecule was smoothly coupled with triarylmethane 5 p to provide conjugate compound 7 via a simple click reaction.…”

“…Dearomatization has been a broadly adopted strategy in catalytic asymmetric transformations and shown enormous power in accessing three-dimensional molecular complexity or possessing modification potential at the typically inert positions. [1][2][3][4][5][6][7][8][9] Because of the extraordinary stability of aromatic structures, the disruption of inherent aromaticity is thermodynamically unfavorable and usually requires harsh reaction conditions. Therefore, a heteroatom-containing arene, such as a phenol or indole, is widely used as the substrate for dearomatization.…”

Asymmetric Dearomatization of Indoles with Azodicarboxylates via Cascade Electrophilic Amination/Aza-Prins Cyclization/Phenonium-like Rearrangement

“…In line with our continuing interest in the catalytic asymmetric dearomatization (CADA) reactions, we have developed a series of chiral phosphoric acid (CPA) catalyzed dearomative cyclization reactions of indoles/pyrroles bearing a pendant nucleophile with external electrophiles . In 2012, Zhang and Antilla reported an elegant asymmetric aminative dearomatization of tryptamine derivatives .…”

Dual visible-light and NHC-catalyzed radical relay trifunctionalization of unactivated alkenes

“…N-Heterocyclic carbene (NHC) catalysis [11][12][13][14][15][16][17] has emerged as one of the most powerful catalytic strategies in the field of organocatalysis, usually by means of a polarity-reversal mechanism. With the rapid development of photocatalysis [18][19][20][21] , recent advances in single-electron transfer (SET)-based radical reactions have further broadened its reaction modes [22][23][24][25][26][27][28] , offering otherwise inaccessible strategies compared to traditional NHC-catalyzed ionic pathways.…”