Benzylic C(sp³)–H Functionalization for C–N and C–O Bond Formation via Visible Light Photoredox Catalysis

Abstract

A visible light mediated highly selective benzylic C-H bond functionalization for intermolecular C-N and C-O bond formation is reported. This cross-dehydrogenative coupling reaction demonstrates a straightforward protocol for incorporating the heteroaromatics to the benzylic position. Benzylic oxidation of various alkyl aryls to corresponding carbonyl compounds has also been reported.

Visible Light‐Induced C−H Bond Functionalization: A Critical Review

“…Recently, a visible light‐induced protocol for benzylic oxidation using a riboflavin tetraacetate (RFT)/Fe catalyst and molecular oxygen has appeared . By using Ir[dF(CF 3 )ppy] 2 (dtbbpy)PF 6 as a visible light‐absorbing photoredox catalyst, Pandey and co‐workers reported a simple and common approach for the benzylic C−H functionalization by way of C−O bond formation.…”

“…In 2016, Pandey and co‐workers successfully demonstrated benzylic C−N bond formation via visible light photoredox catalysis. Under the optimal reaction conditions, the treatment of alkylaryls 1 with the benzotrizole 15 gave the corresponding products 1 6 in good yields (Scheme ).…”

Selective C(sp2)−H Functionalization of Arenes for Amination Reactions by Using Photoredox Catalysis

“…Over the last three decades, our group has been engaged in the area of photoredox catalysis to develop new reactions for the formation of C−C, C−O, and C−N bonds through C(sp 2 )−H functionalization . As a continuation of this research, recently, whilst performing the benzylic amination of 3,4‐dimethoxy toluene ( 3 j ) with benzotriazole ( 5 a ) by using photoredox catalysis, the benzylic amination product was not observed; instead, the aryl amination product ( 8 j ) was isolated in moderate (42 %) yield. This observation led us to hypothesize that the presence of a highly electron‐donating group on the aromatic ring stabilized the radical arene cation, which prompted the nucleophilic reaction of benzotriazole to give the aromatic amination product.…”

Visible light mediated cyclization of tertiary anilines with maleimides using a supported iridium complex catalyst

“…[1][2][3][4][5][6][7][8][9] In particular, the direct couplings of sp 3 C-H bonds adjacent to a tertiary nitrogen atom has attracted increasing attention in recent years. [10][11][12] The cyclization of tertiary anilines and maleimides was the typical visible light mediated reaction, in which the inert C-H bond interacted with a vinyl group to form the cyclic product in one step. [13][14][15][16][17][18][19][20][21][22][23] This transformation could be realized by using Ru(bpy) 3 Cl 2 13 or Ir(ppy) 2 (dtbbpy)PF 6 13 or [Cu(dap) 2 ]Cl 16 as a photocatalyst.…”