Synthesis of 4-aryl-5,5-dimethyl-5H-1,2,3-triazoles and 4-aryl-3-cyano-5,5-dimethyl Δ1-pyrazolines by cycloaddition of 2-diazopropane with iminoethers and propenenitriles

A regiospecific 1,3-dipolar cycloaddition of 2-diazopropane 3 to iminoethers 1a–c, carried out at 0 °C, afforded in two steps the corresponding 4-aryl-5,5-dimethyl-5H-1,2,3-triazoles 5a–c. Under the same conditions, 3-arylpropenenitriles 2a–d led to 3-cyano-5,5-dimethyl Δ1-pyrazolines 6a–d. Products 4–6 were obtained in good yields (69–85%).