Metal-Free Photochemical Imino-Alkylation of Alkenes with Bifunctional Oxime Esters

Abstract

The concurrent installation of C−C and C−N bonds across alkene frameworks represents a powerful tool to prepare motifs that are ubiquitous in pharmaceuticals and bioactive compounds. To construct such prevalent bonds, most alkene difunctionalization methods demand the use of precious metals or activated alkenes. We report a metal-free, photochemically mediated imino-alkylation of electronically diverse alkenes to install both alkyl and iminyl groups in a highly efficient manner. The exceptionally mild reaction conditions, broad substrate scope, excellent functional group tolerance, and facile one-pot reaction protocol highlight the utility of this method to prepare privileged motifs from readily available alkene and acid feedstocks. One key and striking feature of this transformation is that an electrophilic trifluoromethyl radical is equally efficient with both electrondeficient and electron-rich alkenes. Additionally, dispersion-corrected density functional theory (DFT) and empirical investigations provide detailed mechanistic insight into this reaction.

EnT-Mediated N–S Bond Homolysis of a Bifunctional Reagent Leading to Aliphatic Sulfonyl Fluorides

“…Quantum yield analysis using 395 nm single LED determined the iminofluorosulfonylation reaction quantum yield to be Φ = 0.72 (Figure 8H). Therefore, the involvement of a radical chain propagation 55 could not be excluded completely. Plausible Mechanistic Pathway.…”

Metal-free photosensitized radical relay 1,4-carboimination across two distinct olefins

“…12 Recently, we and others have identified a class of benzophenone-based oxime esters as a suitable bifunctional source for supplying both carbon- and nitrogen-centered radicals through energy transfer catalysis. 13–15 Our investigation commenced with the reaction of benzophenone O -pivaloyl oxime ( 1a ), ethene-1,1-diyldibenzene ( 2a ), and acrylonitrile ( 3a ) under visible-light-sensitized conditions (Table 1).…”

Catalytic Chemo‐ and Regioselective Radical Carbocyanation of 2‐Azadienes for the Synthesis of α‐Amino Nitriles

“…[19] Of relevance to this work, Glorius [20] recently developed the photoredox-catalyzed carboimination of alkenes using oxime esters to prepare amino acid derivatives. Gutierrez, Molander and co-workers [21] extended the carboimination to the preparation of CF 3 -containing amines and the synthesis of nitriles. [22] In a complementary approach for the synthesis of α-amino nitriles to our work herein, an alkyl radical is generated and attacks an acrylonitrile, which was then followed by introduction of an imino group by what is proposed to be a chain transfer pathway (Scheme 1d).…”