THE STRUCTURE AND CH-ACIDITY OF CF3-SUBSTITUTED BETA-THIOLACTONES - ATHEORETICAL-STUDY

Ab initio calculations of the molecules of CH3- and CF3-substituted be ta-propiothiolactones and the products of their deprotonation were car ried out by the restricted Hartree-Fock method with full geometry opti mization using the 6-31G basis set. Peculiarities of the geometry and electronic structure of the systems in question were established. Onl y 2-methyl-beta-propiothiolactone forms a mesomeric stabilized carbani on in the case of proton abstraction from the a-position of thiolacton e cycle. Carbanions of 3-methyl, 2-, and 3-thrifluoromethyl-beta-propi othiolactones are stabilized due to the ring opening to form ketene th iolate ions. The CH-acidity of fluorine-containing beta-thiolactones i s much higher than that of nonfluorinated analogs (the differences in the deprotonation energies are 13.4 to 25.2 kcal mol(-1)).