Nitrogen-Bearing Lithium Compounds in Modern Synthesis

Nitrogen-containing compounds are ubiquitous and extremely important in synthesis. This chapter encompasses some general aspects on the generation, structure, and reactivity of nitrogen-bearing organolithiums showing the progress made over the last decade. In particular, the chemistry of reactive intermediates lithiated at sp3- hybridized carbon atoms adjacent (a) to a nitrogen atom is described. Recently developed strategies for the generation and use in synthesis of amino-organolithiums deriving from saturated nitrogenated heterocycles as well as from acyclic nitrogenated systems are reported. Starting from simple three-membered ring aziridines up to seven-membered ring azepines, the reactivity and structural features of the corresponding lithiated intermediates are covered. Special attention has been given to the stereochemistry of the reactions employing amino-organolithiums, and to the development of new and efficient protocols, such as the catalytic dynamic resolution and the catalytic asymmetric deprotonation, for controlling the absolute stereochemistry. The chapter underlines the role of substituents able to activate simple amines towards the lithiation as well as to stabilize the resulting intermediates, establishing the tight relationship between structure and reactivity, offering to researchers the background for testing the reactivity of unexplored nitrogenated systems.