Computational Perspectives on Organolithium Carbenoids

Abstract

Lithium carbenoids are extremely useful reagents in synthetic organic chemistry and have been widely used for generating various reactive intermediates needed for chemical synthesis with high yield under relatively mild conditions. The mechanisms of their reactions are typically quite complex and often strongly influenced by aggregation state, solvent effects, relative stabilities of diastereomers and constitutional isomers, formation of pre-reactive complexes, and Lewis acid catalysis, in addition to factors under the control of the experimentalist, such as reagent preparation, concentration, and temperature. Computational studies are indispensable for understanding the role played by the former factors in the reactions and to gain insights into the impact of the latter on the former. In this chapter, we discuss some themes that have emerged and the insights gained from more than a decade of computational investigations. We focus on two types of organolithium reagents: halomethyllithiums and oxiranyllithiums. They appear to represent contradictory paradigms in certain aspects. In the context of these molecules, we also report on recent studies of the performance of a collection of density functional approximations for reproducing the geometries and energetics predicted by correlated wave function methods.