Reductive dearomative arylcarboxylation of indoles with CO2 via visible-light photoredox catalysis
Wen‐Jun Zhou, Zhe‐Hao Wang, Li‐Li Liao, Yuan‐Xu Jiang, Ke-Gong Cao, Tao Ju, Yiwen Li, Guangmei Cao, Da‐Gang Yu
Abstract
Abstract Catalytic reductive coupling of two electrophiles and one unsaturated bond represents an economic and efficient way to construct complex skeletons, which is dominated by transition-metal catalysis via two electron transfer. Herein, we report a strategy of visible-light photoredox-catalyzed successive single electron transfer, realizing dearomative arylcarboxylation of indoles with CO 2 . This strategy avoids common side reactions in transition-metal catalysis, including ipso-carboxylation of aryl halides and β-hydride elimination. This visible-light photoredox catalysis shows high chemoselectivity, low loading of photocatalyst, mild reaction conditions (room temperature, 1 atm) and good functional group tolerance, providing great potential for the synthesis of valuable but difficultly accessible indoline-3-carboxylic acids. Mechanistic studies indicate that the benzylic radicals and anions might be generated as the key intermediates, thus providing a direction for reductive couplings with other electrophiles, including D 2 O and aldehyde.