75428-95-4Relevant academic research and scientific papers
The effect of crown ethers on the alkylation of a cyclic β-keto ester
Whitney, Richard R.,Jaeger, David A.
, p. 769 - 773 (1980)
The effects of crown ethers (6 and 7) on the reactions of sodium (2a) and potassium enolates (2b) of 2-ethoxycarbonylcyclohexanone (1) with isopropyl iodide in dimethylsulfoxide and dimethoxyethane have been investigated. When the addition of crown ether promoted dissociation of ion pair 2 in either of the two solvents, the total rate of reaction (kt) increased and the ratio of carbon- (3) to oxygen-alkylation (4 and 5) products decreased. The results are consistent with the involvement of both the ion pair and more dissociated species in alkylation and with greater reactivity for the latter.
Quantification of the Nucleophilic Reactivities of Cyclic β-Keto Ester Anions
Corral-Bautista, Francisco,Mayr, Herbert
, p. 7594 - 7601 (2015)
Kinetics of the reactions of enolate anions derived from acyclic and cyclic β-keto esters with benzhydrylium ions and quinone methides have been determined photometrically in dimethyl sulfoxide solution at 20 C. The reactions follow second-order rate laws: first-order with respect to the electrophile and first-order with respect to the enolate. Reactions conducted in the presence of 18-crown-6 ether and in the presence of variable concentrations of K+ allowed the influence of ion-pairing on the nucleophilic reactivities of the various enolate ions to be determined quantitatively. Enolate ions derived from oxocycloalkanecarboxylic esters show reactivities similar to those of their acyclic analogue. Enolate ions derived from δ-lactones are less nucleophilic, which is explained by the enforced (E) conformation of the corresponding esters.
