The forgotten reagent of photoredox catalysis

Abstract

Visible light powers an ever-expanding suite of reactions to both make and break chemical bonds under otherwise mild conditions. As a reagent in photochemical synthesis, light is obviously critical for...

Extending Photocatalyst Activity through Choice of Electron Donor

“…Reductive dehalogenation is a useful model for probing photoactivity, with affordable substrates requiring a wide range of reductive power to engage. 23 Quantitative conversion of the easiest to reduce substrates occurred within 8 h of irradiation with either catalyst, which was monitored using high performance liquid chromatography (Figures S2, S3). As the required energy increased, photoactivity with [Ir(ppy) 2 (phen)] + decreased, affording 62% conversion of 4-bromo-2-fluorobenzonitrile (1d, E p = −1.76 V vs SCE).…”

Applications of red light photoredox catalysis in organic synthesis

“…As we described briefly in the introduction part, several elegant papers have summarized the achievements of NIR photoredox catalysis in recent years. 5 Therefore, herein, we selectively present several representative examples of NIR photocatalysis. Based on the previous reports, 5 we classify NIR photoredox catalysis into three major categories: direct NIR photoredox catalysis, NIR photoredox catalysis through upconversion, and NIR photoredox catalysis through two-photon absorption.…”

“…4 To tackle these limitations, researchers turned their attention to long-wavelength red and NIR lights. 5 Both red light and NIR have characteristics of lower energy, fewer health risks, fewer side reactions, more abundance in sunlight, and most importantly, higher penetration depth through various media. Therefore, red light and NIR photocatalysis can serve as an alternative but milder option for the well-developed white/blue/green-light-mediated reactions.…”

“…Additionally, several reviews have summarized NIR-induced reactions in recent years. 5 Therefore, herein, we mainly focus on red light (620–700 nm) photocatalysis in organic synthesis. Though great success has also been made in its applications in the biological arena and polymer synthesis, 7 they are not included in this review.…”

“…Based on the previously reported photocatalytic activation modes, 5 we classify red light-mediated reactions into direct red light photocatalysis, red light photocatalysis through upconversion, and dual red light photocatalysis (Fig. 4).…”