The chemistry of phosphazenes. synthetic applications of C-alpha-lithiated derivatives

摘要

Phosphazenyl-stabilized carbanions arc polyfunctional synthons, which combine in the same molecule a nucleophilic center adjacent to the phosphorus atom with a variety of functional groups linked to the nitrogen atom. The substituents on the nitrogen have the capability of tuning the reactivity of the anion and may also intervene at a given point of the synthetic pathway. This is a distinguishing feature of C-alpha-lithium phosphazenes with respect to all other phosphorus-stabilized carbanions: they have found application in organic (as for example, in the synthesis of olefins, functionalized open-chain compounds, heterocycles containing phosphorus atoms either in the ring or as appendages of the cyclic system) and inorganic chemistry (e.g. preparation of novel catalysts and polymers with improved properties with respect to the parent polymer).