Visible-light acridinium-based organophotoredox catalysis in late-stage synthetic applications

Abstract

The field of photoredox catalysis has been transformed by the use of organic photocatalysts, which give access to re-activities that were previously only possible with transition-metal photocatalysts.

Metal‐Free Visible‐Light Induced Oxidative Cleavage of C(sp3)−C, and C(sp3)−N Bonds of Nitriles, Alcohols, and Amines

“…As shown in Figure 1(D), there was no sharp oxidation peak observed for selectfluor, but on addition of DMAP a more prominent oxidative peak was observed at 1.36 V vs SCE. Since the excited state reduction potential of Acr‐Mes + ClO 4 − [*E red (PC*/PC − )=+2.08 V vs SCE in MeCN] [46] exceeds this oxidation potential, an excited state reductive quenching pathway is possible for the photocatalyst with the latter one. The fluorescence quenching experiment was also carried out with 4‐methoxy phenyl acetonitrile ( 1 c ), 2‐phenylethanol ( 3 a ) as well as with 4‐methoxy benzylamine ( 5 b ).…”

Modular synthesis of C2-symmetric nitrogen-containing polyaromatics via visible light-enabled reductive aza-6π electrocyclization

“…By virtue of the similar oxidation potential of the newly designed dication salt Me-3d to that of Nicewicz's acridinium salt PC1 (+2.02 V vs. +2.15 V), Me-3d was supposed to act as one of the most oxidizing organic photocatalysts known. 20 Under visible-light irradiation, it showed strong oxidizing capacity, which could promote a broad range of challenging direct carbon–hydrogen (C–H) bond activations. To validate our hypothesis, two typical acridinium salt-promoted model reactions (site-selective arene C–H amination and C–H trifluorometlylation of imidazopyridine) were elected to test the catalytic efficiency of Me-3d .…”

Symmetric dicyanobenzothiadiazole (DCBT) dyes with a 1.5 eV excited state reduction potential range

“… 10–18 In these systems, a strong photooxidant is often used to create greater driving forces in order to achieve higher efficiencies and to access new reactions. 4,19–23 Depending on the photooxidant used, selectivity towards certain processes can also be increased. 23–26 Molecular photooxidants are often characterized by two important features, oxidizing strength as well as excited state (ES) lifetime.…”