Heterogeneous Visible-Light Photoredox Catalysis with Graphitic Carbon Nitride for α-Aminoalkyl Radical Additions, Allylations, and Heteroarylations

Abstract

A protocol for the photooxidative activation of α-silylamines and α-amino acids for desilylative and decarboxylative additions, allylations and heteroarylations in the presence of graphitic carbon nitride (g-C 3 N 4) was developed. The procedure has broad scope and provides the desired products in high yields. The heterogeneous nature of the g-C 3 N 4 catalytic system enables easy recovery and recycling as well as the use in multiple runs without loss of activity. The photoredox catalyzed reactions can also be conducted in continuous photo flow fashion and scaled up to gram-scale. Thus, the stable and readily available polymeric g-C 3 N 4 provides an alternative to homogeneous photosensitizers for the generation of valuable radical intermediates for applications in synthesis and catalysis.

Photoredox Organic Synthesis Employing Heterogeneous Photocatalysts with Emphasis on Halide Perovskite

“…In an early work, for instance, in 2009, Wang et al [82] employed directly photo-oxidation of benzene to produce phenol by using Fe modified C 3 N 4 and further [83] explored the selective oxidation of alcohols to ketones with C 3 N 4 and O 2 .Z hao et al [13a] and Quadrelli et al [84] also extended this O 2 and C 3 N 4 based photo-oxidations trategy towards[ 4 + +2] alkene cycloaddition and alkene oxidation, respectively.F urther,a ss hown in Figure 4, Kçnig'sg roup [85] explored vinyl sulfone synthesis from alkenes and sulfinate salts by oxidation of the sulfinatesu sing cyanamide-functionalized carbon nitride photocatalysts (see Figure4a). Rueping's group [86] also employed g-C 3 N 4 for photooxidative activation of a-silylamines and a-aminoacids for desilylative and decarboxylative additions, allylations, andh eteroarylations (see Figure 4b).…”

Recyclable Perovskite as Heterogeneous Photocatalyst for Aminomethylation of Imidazo‐Fused Heterocycles

“…Initially, a single electron transfer (SET) from 2 a to the hole leads to the formation of radical 5 with the releasing of CO 2 and proton. [19] The addition of radical 5 to the C=C bond of 1 a affords radical 6, which immediately undergoes a single electron oxidation delivering the intermediate 7.…”

Towards Visible‐Light Photocatalytic Reduction of Hypercoordinated Silicon Species

“…A SET oxidation‐desilylation of benzyltrimethysilanes involving visible‐light excited chiral iminium ions, 9‐mesityl‐10‐methylacridinium perchlorate salt or graphitic carbon nitride as a catalytic and strong photooxidant, allowed the formation of benzylic radicals which can be trapped by ground‐state iminium ions or Michael ‐type acceptors respectively. In the same vein, α ‐alkoxymethyl radicals were successfully generated from the corresponding α ‐silyl ethers by photocatalyzed oxidation, as well as acyl radicals from acyl silanes .…”