Pericyclic reactions

This chapter on pericyclic reaction gives an introduction to molecular orbitals and their symmetry properties. The ‘Correlation Diagram’ method has been illustrated by discussing suitable examples. The outcome of major types of pericyclic reactions, the cycloaddition reactions, the electrocyclic reactions and the sigmatropic rearrangements, has been illustrated using FMO approach. The importance of chair-like transition state in Cope rearrangement and Claisen rearrangement has been illustrated. The effect of energy gap between HOMO and LUMO on the rates of Diels-Alder reaction has been provided. The effect of substituents on the energy levels of HOMO-LUMO has been discussed. Discussion has been provided to illustrate the role of orbital coefficients on the regioselectivity of cyclo-addition reaction. A brief discussion has been provided on 1,3-Dipolar cycloaddition reactions.