Preparation and reactions of 3-phosphinyl-1-aza-1,3-butadienes. Synthesis of phosphorylated pyridine and pyrazole derivatives

3-Phosphinyl 1-aza-1,3-butadienes are obtained by aldol condensation between hydrazonoalkyl phosphine oxides and N,N-dimethylformamide dimethyl acetal. Transamination reaction of these azadienes with amines yields functionalized 1-aza-1,3-butadienes . Cycloaddition processes of these azadienes with electron-poor dienophiles to give phosphorylated pyridine derivatives and are also reported, while intramolecular cyclization reaction of heterodiene affords phosphorylated pyrazole .