A DFT reinvestigation of chemo- and stereoselectivity epoxidation from α- and ɣ-trans himachalene with meta Chloroperoxybenzoic acid

Abstract

In this work the epoxidation reaction of the α- and ɣ-trans himachalene in the presence of meta chloroperoxybenzoic acid (m-CPBA) has been studied within the Density Functional Theory (DFT) method at the B3LYP/6-311G(d,p) level in dichloromethane as a solvent, in order to shed light on the chemo- and stereoselectivity in the course of the reaction. Analysis of the Conceptual Density Functional Theory (CDFT) reactivity indices indicate that the m-CPBA will behave as electrophilic while α- and ɣ-trans himachalene will behave as a nucleophile and the attacks observed experimentally are correctly predicted by the electrophilic Pk + and nucleophilic Pk - Parr functions. The two reactive paths associated with chemo and stereoselectivity approach modes of m-CPBA on C=C reactive sites in α and ɣ-trans himachalene have been analyzed. They showed that m-CPBA reacted as electrophile whereas α- and ɣ- trans himachalene as a nucleophile. The Monoepoxidation of α- and ɣ- trans himachalene leads to the formation of two stereoisomers, on the most substituted double bond "C=C», one of the two is a majority. The diepoxidation reaction of α- and ɣ- trans h