Reactivities of tertiary phosphines towards allenic, acetylenic, and vinylic Michael acceptors.

ABSTRACT: The addition of phosphines (PR₃) to Michael acceptors is a key step in many Lewis-base catalysed reactions. The kinetics of the reactions of ten phosphines with ethyl acrylate, ethyl allenoate, ethyl propiolate, ethenesulfonyl fluoride, and ethyl 2-butynoate in dichloromethane at 20 °C was followed by photometric and NMR spectroscopic methods. The experimentally determined second-order rate constants k ₂ show that electronic effects in sterically unencumbered phosphines affect their nucleophilicity towards different classes of Michael acceptors in the same ordering. Michael acceptors with sp-hybridised electrophilic centres, however, are less susceptible to changes in the PR₃ nucleophilicity than those with sp²-hybridised reactive sites. L

SUBMITTER: An F 

PROVIDER: S-EPMC11474661 | biostudies-literature | 2024 Oct

REPOSITORIES: biostudies-literature