https://www.selleckchem.com/pr....oducts/pembrolizumab
In this paper, a series of new substituted-5-pyrazolones were first synthesized, then formulated by the Vilsmeier-Haack reaction to obtain substituted-4-carbaldehyde-5-pyrazolones. In the final step, when urea was reacted with formulated pyrazolones, we found that, instead of the C=N bond in azomethine form, the compounds tautomerized to form a series of novel pyrazole-4-ylidenemethylurea structures. The structures of these compounds were elucidated by FTIR, 1H, 13C NMR, LC-MS/MS, and elemental analysis methods. The cytotoxic and