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.