Abstract 1-Alkyl-1-(2, 3-butadienyl) hydrazines 1b, d—g can be oxidized under mild conditions to yield 1-alkyl-2-(1-methylen-2-propenyl) diazenes 3. These E-configurated azo compounds are precursors for rapid inter-and intramolecular [4+ 2] cycloadditions to give ...