Synthesis and [2+4]cycloadditions of two 1-aza-1,3-butadiene-1-carbonitriles

3-Methyl- and 3-ethyl-1-aza-1,3-butadiene-1-carbonitriles were synthesized by reaction of the corresponding 3-alkylacroleins with bis(trimethylsilyl)-carbodiimide using titanium tetrachloride as catalyst. They were highly reactive and difficult to purify rigorously. Attempted anionic polymerizations gave only oligomers of molecular weight ∼500 Da. These 3-alkyl-azadienecarbonitriles cycloadded to the electron-rich olefins iso-butyl vinyl ether and p-methoxystyrene to give [2+4] cycloadducts with moderate yields.