New synthetic methods for α,β -unsaturated ketones, aldehydes, esters and lactones by the palladium-catalyzed reactions of silyl enol ethers, ketene silyl acetals, and enol acetates with allyl carbonates
Silyl enol ethers and ketenesilylacetals derived from ketones, aldehydes, esters and lactones are converted into α,β-unsaturated ketones, aldehydes, esters and lactones by treatment with allyl carbonates in high yields using the palladium—bis(diphenylphosphino)ethane (dppe) complex as catalyst. Phosphine-free palladium catalyst instead of the palladium—phosphine complex gives a higher selectivity
α-Vinylation of Ester Equivalents via Main Group Catalysis for the Construction of Quaternary Centers
作者:Chloe G. Williams、Sepand K. Nistanaki、Conner W. Wells、Hosea M. Nelson
DOI:10.1021/acs.orglett.3c00535
日期:2023.5.26
A methodology for the construction of sterically congested quaternary centers via the trapping of vinyl carbocations with silylketeneacetals is disclosed. This main group-catalyzed α-vinylation reaction is advantageous as methods to access these congested motifs are limited. Moreover, β,γ-unsaturated carbonyl moieties and tetrasubstituted alkenes are present in various bioactive natural products