The visible-light-induced acylation/cyclization of alkynoates with acyl oximes for the construction of 3-acylcoumarins

Abstract

A nitrogen-centered radical-mediated strategy is described to synthesize functionalized 3-acylcoumarins. This process is enabled by visible-light-induced acylation/cyclization reactions of alkynoates with various acyl oxime compounds in acetonitrile. The difunctionalization of...

Visible‐Light‐Induced Acylation/Arylation of Alkenes via Aryl Migration/Desulfonylation

“…Acyl oxime esters could be reduced through single electron transfer in the presence of photocatalyst to yield highly reactive iminyl radicals, which underwent β‐C−C bond fragmentation to disconnect acyl radicals from iminyl radicals through elimination of a nitrile molecule (Scheme 1c). The resulting acyl radicals could be coupled with a wide range of radical acceptors, including alkenes, [15a–c] aromatic rings, [15d] and alkynes [15e–g] . For example, Wu and co‐workers reported a photocatalytic acyl radical cascade reaction between acyl oxime esters with acrylamides and styrenes, respectively [15a] .…”

“…In 2020, Yang and co‐workers achieved a phosphoranyl‐radical‐promoted the hydroacylation of alkenes using acyl oximes as acyl radical source under photocatalytic conditions, which provides a facile route toward valuable ketones synthesis [15c] . Recently, our group reported the visible‐light‐induced acyl radical transfer followed by cyclization reactions using alkynes‐containing molecule as reactants including propiolamides, [15e] N ‐propargylindoles, [15f] and alkynoates [15g] as the radical acceptors. With our continuing interests in the development of oxime esters involved organic transformations under photoredox catalysis, [15e–f,16] we herein reported the radical cascade reaction [17] of N ‐tosyl acrylamide [18] with acyl oxime esters to prepare acylated indolin‐2‐ones through a tandem acyl radical addition/aryl migration [19] /desulfonylation/cyclization process on the basis of NCR strategy (Scheme 2).…”

Recent Advances in Molecule Synthesis Involving C-C Bond Cleavage of Ketoxime Esters

“…Alkynes with specific substituents, such as alkyne amides [ 51 , 52 , 53 ], N -propylindoles [ 54 , 55 , 56 ], alkyne esters [ 57 , 58 ], alkyne amines [ 59 , 60 , 61 ], etc., are often used as radical acceptors to construct potential heterocyclic compounds by tandem cyclization. Recently, Liu and Zhou have independently developed a multitude of innovative photocatalytic, nitrogen-centered, radical-mediated acylation strategies of reactive alkynes using acyl oxime esters as acyl sources ( Scheme 10 ) [ 37 , 39 , 62 , 63 ].…”

Visible-Light-Induced Dual Acylation of Alkenes for the Construction of 3-Substituted Chroman-4-ones

“…The use of acyl oxime as acyl radical precursors has been well developed in visible-light-induced acylation of alkenes (Scheme , path I–III) . Recently, our group also reported visible-light-induced acylation of alkynes (propiolamides, N -propargylindoles and alkynoates) through the same tactics (Scheme , path IV–VI) …”