Visible‐Light‐Induced Dearomatizations

Abstract

The dearomatization of aromatic compounds is an important synthetic strategy used in accessing complex three‐dimensional structures from simple aromatic precursors. This minireview aims to provide an overview of recent advancements in this area, with a specific focus on visible‐light‐mediated dearomative transformations. Compared to the conventional high‐energy ultraviolet (UV) light‐promoted processes, not only these new approaches offer milder reaction conditions to accommodate wider variety of substrates with sensitive functionalities, but also enable the use of photocatalysts and other promoters, significantly expanding the reaction space. Application of these transformations to the synthesis of bioactive compounds are also discussed.

Spirocyclizative Remote Arylcarboxylation of Non-Activated Arenes with CO2 via Visible-Light-Induced Reductive Dearomatization

“…Furthermore, the reaction was explored with 2-tethered naphthalenes and phenyl aromatics (Scheme 4). Pleasingly, after subjected to our reaction conditions, 2-tethered naphthalenes led to 1,2-arylcarboxylation dearomatized products (45)(46)(47)(48) whose structures were different from abovementioned remote 1,4arylcarboxylation of 1-tethered naphthalenes, albeit in moderate yields. Of note, some 1,2-hydroarylation side product (10-20%) was also generated with these substrates.…”

Advances in Catalytic Asymmetric Dearomatization

“… 57 To break through this predicament, one probably needs very reactive reaction partners that are generated under mild conditions and well embedded in a subtle chiral environment. To this end, we expect that the implementation of modern catalytic technologies, such as visible-light-catalysis, 58 electrocatalysis, 59 nanocatalysis, etc., can revolutionize the seminal dearomatization reactions discussed in the Introduction by bringing about their catalytic asymmetric variants. In addition, the known enzyme-promoted asymmetric dearomatization of nonactivated arenes might provide an alternative solution by stimulating de novo design of small molecule catalysts that mimic relevant enzymes or by improving the performance of such enzymes employing directed evolution technology.…”

Organophotocatalytic dearomatization of indoles, pyrroles and benzo(thio)furans via a Giese-type transformation

“…The dearomatization of arenes has become a powerful platform for the facile construction of highly valued molecular architectures [10][11][12][13][14][15] . The dearomatization of indoles constitutes the most efficient strategy for accessing indolines [1][2][3][4][5][6][7][8] .…”

“…Single-electron transfer (SET) involved oxidation-induced C-H functionalization of the nucleophilic indoles has been elegantly realized as powerful alternatives for indole dearomatization 17 , particularly mild, green visible light photocatalytic and electrochemical methods (Fig. 1a) 3,15,[18][19][20][21][22][23][24][25][26][27][28][29] .…”