Electrophilic reactivities of cyclic enones and alpha,beta-unsaturated lactones

Mayer, Robert J.; Allihn, Patrick W. A.; Hampel, Nathalie; Mayer, Peter; Sieber, Stephan A. and Ofial, Armin R. (2021): Electrophilic reactivities of cyclic enones and alpha,beta-unsaturated lactones. In: Chemical Science, Vol. 12, No. 13: pp. 4850-4865

Abstract

The reactivities of cyclic enones and alpha,beta-unsaturated lactones were characterized by following the kinetics of their reactions with colored carbon-centered reference nucleophiles in DMSO at 20 degrees C. The experimentally determined second-order rate constants k(2) were analyzed with the Mayr-Patz equation, lg k = s(N)(N + E), to furnish the electrophilicity descriptors E for the Michael acceptors. Cyclic enones and lactones show different reactivity trends than their acyclic analogs. While cyclization reduces the reactivity of enones slightly, alpha,beta-unsaturated lactones are significantly more reactive Michael acceptors than analogously substituted open-chain esters. The observed reactivity trends were rationalized through quantum-chemically calculated Gibbs energy profiles (at the SMD(DMSO)/M06-2X/6-31+G(d,p) level of theory) and distortion interaction analysis for the reactions of the cyclic Michael acceptors with a sulfonium ylide. The electrophilicities of simplified electrophilic fragments reflect the general reactivity pattern of structurally more complex terpene-derived cyclic enones and sesquiterpene lactones, such as parthenolide.

• Item Type: Journal article
• Faculties: Chemistry and Pharmacy > Department of Chemistry
• Subjects: 500 Science > 540 Chemistry
• ISSN: 2041-6520
• Language: English