Vs. Martin et al., ENANTIOSELECTIVITY IN SYNTHESIS AND ALKYLATION OF HIGHLY SUBSTITUTED GAMMA-LACTONES - SEMIEMPIRICAL MODEL, Anales de quimica, 89(1), 1993, pp. 85-88
The enantioselective synthesis of some gamma-lactones by an intramolec
ular Michael type addition on alpha,beta-unsaturated esters is rationa
lized by the relative thermodynamic stabilities of the possible final
products, examined by semi-empirical methods. The structure of the alp
ha-anion obtained by basic treatment permits the remarkable diastereos
election shown by the alkylation to be understood. Free anions and che
lated ones with metal sparkles or a lithium cation (MNDO) are analyzed
as well as the possible solvent effects.