Pyrazole誘導体の研究 (第8報)

Propionitrile誘導体ならびに関連化合物とArylhydrazineとの反応について 補遺

抄録

By the reaction with arylhydrazines, 2-ethoxymethyl-3-ethoxy-3-methoxypropionitrile (I), 2-methoxymethylene-3-ethoxypropionitrile (II), 2-(1-ethoxy-1-methoxymethyl) acrylonitrile (III), ethyl 2-ethoxymethyl-3-ethoxy-3-methoxypropionate (IV), and 2-methoxymethylene-3-ethoxypropionate (V) gave pyrazole derivatives similary and both 1-phenyl-2-pyrazoline-4-carbonitrile (XVIII) and ethyl 1-phenyl-2-pyrazoline-4-carboxylate (XIX) have been newly obtained from the reaction with phenylhydrazine as intermediates. In the reaction with I, o-methylsulfonylphenylhydrazine gave the corresponding 1-aryl-3-pyrazoline-4-carbonitrile (XX), and p-methylsulfonylphenylhydrazine, o- and p-tolylhydrazine produced the corresponding 1-arylpyrazole-4-carbonitrile (XXI, XXII and XXIII). In this series of reaction, when substitutional radicals of forming hydrogen bond is located at the ortho position of arylhydrazine, it will be stabilized by the production of 3-pyrazoline, and if not, 2-pyrazoline is prepared, followed by the dehydration to pyrazole. 2, 4-Dinitrophenylhydrazine and 2-methyl-3-ethoxy-3-methoxy-propionitrile (XXIV) gave 1-(2, 4-dinitrophenyl)-4-methyl-5-aminopyrazole (XXVII) and ethyl 2-methyl-3-ethoxy-3-methoxypropionate (XXVIII) gave propionaldehyde 2, 4-dinitrophenylhydrazone (XXIX).