This review summarizes research results concerning the reactions of phosphonyl carbanions with different carbon-nitrogen
systems, amines, amides, imines, oximes, hydrazones, nitriles, diazo compounds, isocyanates, and azides, reported by us and other research
group over the last years. It outlines the utility of such reactions in various aspects of heterocyclic chemistry. Some of these reactions
have been applied successfully to the synthesis of biologically important compounds. A brief account on the synthesis of Horner
reagents was also displayed.