Visible-light promoted γ-cyanoalkyl radical generation: three-component cyanopropylation/etherification of unactivated alkenes

Abstract

A photoredox approach to generate distal cyano-substituted alkyl radicals through C-C bond cleavage of cyclobutanone oximes was developed. The radicals produced by this method were applied to three-component cyanopropylation/etherification of unactivated alkenes. Their reactions with diverse radical acceptors were also demonstrated.

Photoinduced C—C Bond Cleavage and Oxidation of Cycloketoxime Esters

“…To further clarify the oxygen resource of the product and verify our proposal, we operated the reaction in 18 O-labeled DMSO (89% of 18 O) under the standard conditions. As anticipated, the 18 O incorporated product 2aa( 18 O) was obtained in high ratio confirming that the oxygen atom in the product was derived from DMSO itself (Scheme 3a).…”

“…[9] In extention, herein, we report a novel transformation of photocatalytic C-C bond cleavage of cycloketoxime esters to construct cyano-containing ketones, [10] in which DMSO acts as the terminal oxidant for oxygenation and the oxime ester group is the source of nitrogen ( Figure 1b). While catalytic thermal ring opening of cyclobutanone oximes and other derivatives by C-C bond β-scission reactions of iminyl radical [16] has been extensively exploited, [17] mild visible lightdriven variation [18] especially using unstrained rings has been considerably overlooked. [11] Recently, C-H oxidation of benzenethiol, [12] diarylmethanes, toluenes, [13] ketones, [14] and styrenes [15] using DMSO as the oxygen source has been reported ( Figure 1c).…”

Radical‐Promoted C−C Bond Cleavage: A Deconstructive Approach for Selective Functionalization

“…During the last two years,Chen, Xiao and co-workers [55] as well as the group of Zhou group, [56] have reported anumber of studies on the photoinduced reductive fragmentation of Oacyl oxime derivatives.D espite the extraordinary advances achieved in reductive approaches,fragmentation of unstrained rings has so far been significantly overlooked. Jiao,S hi, and co-workers reported ap hotoinduced deconstruction/ oxidation of unstrained cycloketoxime esters (33).…”

Synthesis of Functionalized Nitriles by Microwave‐Promoted Fragmentations of Cyclic Iminyl Radicals

“…Recent reports by Selander, Shi, and Zhou have advanced the state of the art by enabling iminyl radical fragmentations in the absence of hydrogen atom donors. The alkyl radicals are trapped by alkenes, forging new C−C bonds in the adducts (Scheme ).…”