Ab Initio Investigations of the Rearrangements of some β-Haloalkoxides to Epoxides via G3 Calculations

The conformational analysis of five β-chloro- and β-bromo-alkoxides had been done. the minima and the conformational transition states were determined. the anti conformer was found to be the most stable one. its percentage is more than 99. α-methylation increases the nuclophilicity of oxygen .consequently, it enhances the rate of the ring closure. in contrast to β- methylation which retards the rate of the ring closure. this observation could be attributed to the reactivity of alkyl halides in sn2 reactions. the rearrangements of g and g-conformers to carbonyl compounds are not feasible. therefore, the main rearrangement that takes place in β- haloalkoxides is the formation of epoxides.