Understanding [3 + 2] cycloaddition reactions from the molecular electron density perspective : A new theoretical outlook on organic reactions

Department of Chemistry, Durgapur Government College,

Durgapur-713 214, West Bengal, India

Central Ayurveda Research Institute (CARI),

Calcutta-700 091, West Bengal, India

E-mail: ablabcu@yahoo.co.uk

Cycloaddition reactions share the top shelf priority in the toolbox of organic chemists owing to their diverse pharmaceutical and industrial applications. The frontiers molecular orbital (FMO) theory has been used to study the reactivity of cycloaddition reactions since nearly the last five decades, though there have been criticisms, and even instances of failures. In 2016, an appealing alternative has been proposed by Domingo, namely the molecular electron density theory (MEDT), to underline the decisive role of changes in electron density in the observed molecular reactivity of chemical reactions. MEDT uses a set of advanced quantum chemical tools and has been extensively applied to analyze organic reactions, particularly focussed on cycloadditions in more than 250 studies since last six years to cover varied aspects such as reactivity, substituent effects, catalysis, solvent effects, strain promotion, regio-, stereo- and chemoselectivity. This article is intended to present a brief overview of MEDT for analysis of [3 + 2] cycloaddition reactions by experimentalists and theoretical chemists.