Epoxide ring opening reactions fluorine substitution effect

A detailed kinetic study using UV-vis, FTIR (Fourier-transform infrared), and NMR spectroscopy a Hammett plot with /0 = -h1.98 using para-substituted styrene oxides an inverse solvent kinetic isotope effect (KIE) (fcnHp/ HHP-d2) = 0.86 and nonlinear effects studies" have all shown that the (salen)Co- (J) and amidine-co-catalysed enantioselective ring opening of terminal- and mew-epoxides by fluoride ion (forming trans- -ttuoTO alcohols in a 42-89% yield with 84-99% ee) occurs by the mechanism shown in Scheme 5. /-BuOOH oxidizes the Co(H) to Co(III) in the (salen)Co(III) catalyst. PhCOF provides the fluorine for the reaction. 

---