AB-INITIO MO STUDY OF THE STEREOSELECTIVE OXIDATION OF [3.2.1]-BRIDGED BICYCLIC DISULFIDES

A theoretical study of the first oxidation step of [3.2.1] bridged bic yclic disulphides to thiosulphinates was performed with hydrogen perox ide and performic acid in order to understand the exo/endo selectivity . Ab initio molecular orbital calculations were carried out with the 3 -21G basis set. Key equilibrium geometries were optimized at the RHF and MP2 level. Transition states single-point energy calculations were performed at MP2 level with RHF geometries. The entrance channel for the oxygen transfer showed the peroxide bond oriented-along the direct ion of the localized p-pure lone pair. This highly-oriented reaction p ath was probably responsible for the stereoselective attack on the exo face. Study of the substituent effect on stereoselective oxidation wa s attempted. A comparison between calculated and experimental structur e of the reaction product was reported. The relative stability of dias tereomers was calculated in the gas phase and in solution.