RESUMO
In catalytic α-alkylation reactions of carbonyl compounds, although SN2-type substitution reactions of enolates with alkyl halides are a conventional methodology, addition reactions with alkenes are more desirable because of their atom-economical character; however, reactions with nonactivated alkenes are challenging. Here, we developed highly efficient catalytic α-alkylation reactions of active methylene and methine compounds with nonactivated alkenes such as 1-decene using an organophotocatalyst and lithium thiophenoxide as a Lewis acid/Brønsted base/hydrogen atom transfer (HAT) multifunctional catalyst under blue-light irradiation. The reaction was also performed with a higher degree of efficiency under a continuous-flow system to obtain the products in multigram scales. The present reaction system enables highly efficient and practical α-alkylation reactions of active methylene and methine compounds to be achieved.
RESUMO
Addition reactions of ketene silyl acetals with alkenes that do not have an electron-withdrawing group are generally difficult because the nucleophilicity of ketene silyl acetals and the electrophilicity of alkenes are not sufficient. Herein, we report photocatalytic addition reactions of ketene silyl acetals with alkenes that proceed through formation of α-carbonyl radicals. In the presence of an appropriate protic additive, the reactions proceeded smoothly under blue-light irradiation to afford the desired products in moderate to high yields.
Assuntos
Acetais , Alcenos , Etilenos , CetonasRESUMO
Under blue-light irradiation conditions with a photocatalyst [1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene], silyl enol ethers reacted with alkenes in the presence of a small amount of water to afford the α-alkylation products in good to high yields. A thiol cocatalyst was found to expand the substrate scope of the reaction.
