Abstract Alkylation of methyl 4-methyl 5-oxo 5-phenyl (m and p-X substituted) pentanoates 1a-b give cis and trans tetrahydro 5,6-dimethyl 6-phenyl 2H pyran-2-ones. LFER of isomer ratios as function of the X substituent on the phenyl ring is seen in MeLi-Et2O. The lactone ratios of reactions in THF with MeMgCl are not affected by the X phenyl substituent, while a more complex situation is showed by reactions of MeMgl in Et2O and benzene. Changes in the cis: trans-ratios with variations in reactant and solvent are discussed in terms of equilibrium between folded and unfolded conformations in transition states.
δ Lactones from δ-ketoesters-II : Mechanism changes in alkylation reactions and substituent effects on stereoselection / DI MAIO, Giorgio; Vecchi, Elisabetta Maria; Zeuli, Errico; Delfini, Maurizio. - In: TETRAHEDRON. - ISSN 0040-4020. - STAMPA. - 40:4(1984), pp. 749-755. [10.1016/S0040-4020(01)91103-2]
δ Lactones from δ-ketoesters-II : Mechanism changes in alkylation reactions and substituent effects on stereoselection
DI MAIO, Giorgio;VECCHI, Elisabetta Maria;ZEULI, Errico;DELFINI, Maurizio
1984
Abstract
Abstract Alkylation of methyl 4-methyl 5-oxo 5-phenyl (m and p-X substituted) pentanoates 1a-b give cis and trans tetrahydro 5,6-dimethyl 6-phenyl 2H pyran-2-ones. LFER of isomer ratios as function of the X substituent on the phenyl ring is seen in MeLi-Et2O. The lactone ratios of reactions in THF with MeMgCl are not affected by the X phenyl substituent, while a more complex situation is showed by reactions of MeMgl in Et2O and benzene. Changes in the cis: trans-ratios with variations in reactant and solvent are discussed in terms of equilibrium between folded and unfolded conformations in transition states.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
