A novelcatalyticsystem based on copper(I) and chiral bis(phosphine) dioxides is described. This allows the arylation of silyl enol ethers to access enolizable α-arylated ketones in good yields and enantiomeric excess up to 95%. Noncyclic ketones are amenable substrates with this method, which complements other approaches based on palladium catalysis. Optimization of the ligand structure is accomplished
Selective α-Methylation of Aryl Ketones Using Quaternary Ammonium Salts as Solid Methylating Agents
作者:Johanna Templ、Michael Schnürch
DOI:10.1021/acs.joc.1c03158
日期:2022.3.18
We describe the use of phenyl trimethylammonium iodide (PhMe3NI) as an alternative methylatingagent for introducing a CH3 group in α-position to a carbonyl group. Compared to conventional methylatingagents, quaternary ammonium salts have the advantages of being nonvolatile, noncancerogenic, and easy-to-handle solids. This regioselective method is characterized by ease of operational setup, use of
Exogenous Ligand-Free NiH-Catalyzed Hydroacylation of Aryl Alkenes with Aroyl Fluorides
作者:Jihye Kim、Jieun Jang、Yoonho Lee、Kwangmin Shin
DOI:10.1021/acs.orglett.2c02110
日期:2022.7.29
Acylfluorides have emerged as efficient acyl group donors, but these attractive reagents have rarely been utilized in transition-metal-catalyzed hydroacylation. Herein we report a nickel hydride-catalyzed hydroacylation of aryl alkenes using aroyl fluorides. The reaction proceeds without recourse to an exogenous ligand under mild conditions. The synthetic utility of the present method is demonstrated
photocatalytic metal-free cross-coupling of benzylic and aldehydic C–H bonds by synergistic catalysis of organophotocatalyst 4CzIPN and a thiol, which affords the corresponding α-aryl ketones in acceptable yields along with hydrogen evolution. The mechanistic investigation indicates a radical–radical coupling to give an intermediary alcohol, followed by an acceptorless alcohol dehydrogenation.