Electrostatic origin towards the reversal of π-facial selectivity of 5,6-cis,exo-disubstituted bicyclic[2.2.2]oct-2-enes with m-chloroperbenzoic acid and diazomethane: a computational study

A computational (B3LYP/6-31G∗ and MP2/6-31G∗) study shows that electrostatic interaction is controlling the π-facial selectivity for the addition of peracid and diazomethane to 5,6-cis,exo-disubstituted bicyclic[2.2.2]oct-2-enes (1). The nitrogen centre of diazomethane which does not participate in bond formation governs the π-face selectivity in 1,3-dipolar cycloaddition reactions with 1. The calculated results show that Cieplak model is less important in controlling the face selectivity in these cases.

The π-facial selectivity of 5,6-disubstituted bicyclic [2.2.2]oct-2-enes with m-cpba and diazomethane has been studied computationally. The reversal of face selectivity with m-cpba and diazomethane arises due to an electrostatic effect. The calculations further revealed that an atom centre of an electrophile which is not directly involved in the bond formation can govern the face selectivity.