An efficient solvent-free synthesis of NH-pyrazoles from beta-dimethylaminovinylketones and hydrazine on grinding

作者：Longhi Kelvis; Moreira Dayse N; Marzari Mara R B; Floss Vagner M; Bonacorso Helio G; Zanatta Nilo; Martins Marcos A P^*

来源：Tetrahedron Letters, 2010, 51(24): 3193-3196.

DOI：10.1016/j.tetlet.2010.04.038

• Enaminones
• Pyrazoles
• Grinding
• Solvent-free conditions

A series of NH-pyrazoles was efficiently synthesized from the reaction of beta-dimethylaminovinylketones ([R(1)C(O)C(R(2))=CHN(Me(2))], where R(1) = Me, Ph, 3-MeO-Ph, 4-Me-Ph, 4-MeO-Ph, 4-F-Ph, 4-Cl-Ph, 4-Br-Ph, 4-O(2)N-Ph, fur-2-yl, thien-2-yl; R(2) = H, 2-MeO-Ph; R(1), R(2) = -(CH(2))(3)C(O)-) and hydrazine sulfate in solid state on grinding in the presence of p-toluenesulfonic acid (PTSA). Most of the reactions proceeded smoothly at room temperature under solvent-free conditions. In comparison with the classical reaction conditions, which employ molecular solvent (ethanol), this new synthetic method has the advantages of shorter times, higher yields, mild reaction conditions as well as being environmentally friendly.

• 出版日期2010-6-16