Base and solvent mediated decomposition of tosylhydrazones: highly selective synthesis of N-alkyl substituted hydrazones, dialkylidenehydrazines, and oximes

Base and solvent mediated decomposition of tosylhydrazones was studied. It was found that reaction of tosylhydrazones in CH3NO2 in the presence of 1 equiv of K2CO3 in 90 °C gave N-alkylated products in 52–96% yield. However, when the same reaction was carried out in mixed solvent of CH3NO2 and dioxane in the presence of 3 equiv of NaOH at 110 °C, dialkylidenehydrazines were obtained in moderate to high yield. If the reaction was carried out in mixed solvent of CH3NO2 and DMSO in the presence of 10 equiv of NaOH at 110 °C, CH3NO2 can act as the precursor of hydroxylamine and corresponding oximes were formed in up to 92% yield.