86051-92-5Relevant articles and documents
δ-LACTONES FROM δ-KETOESTERS-II; MECHANISM CHANGES IN ALKYLATION REACTIONS AND SUBSTITUENT EFFECTS ON STEREOSELECTION
Maio, G. Di,Vecchi, E.,Zeuli, E.,Delfini, M
, p. 749 - 756 (1984)
Alkylation of methyl 4-methyl 5-oxo 5-phenyl (m and p-X substituted) pentanoates 1a-h 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 the reactions in THF with MeMgCl are not affected by the X phenyl substituent, while a more complex situation is showed by reactions of MeMgCl 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.