ALKALINE-HYDROLYSIS OF N-METHYLAZETIDIN-2-ONE - HYDRATION EFFECTS

Semiempirical calculations (PM3) have been used to investigate the rea ction mechanism (B-AC2) Of the alkaline hydrolysis of N-methylazetidin -2-one. This mechanism involves the nucleophilic attack of a hydroxyl ion on the carbonyl carbon to give a tetrahedral complex followed by c leavage of the C-N bond and proton transfer to form the final product. The influence of the solvent in this process has been analyzed using the supermolecular approach with a water solvation sphere of 20 molecu les around the solute. The results obtained have been compared with th ose based on a continuum treatment of the solvent with semiempirical a nd ab initio methodology. The potential barrier of 17.5 kcal mol(-1) d ue to the attack of the nucleophile is very close to the experimental value (16.1 kcal mol(-1)) and the final product is about 52 and 27 kca l mol(-1) more stable than the reactives and the tetrahedral intermedi ate, respectively. (C) 1998 Elsevier Science B.V.