Aminopyrazole; II¹.C-Unsubstituierte 1-Alkyl-3-aminopyrazole aus 2-Chloroacrylnitril bzw. 2,3-Dichloropropannitril und Alkylhydrazinen

Phototransposition chemistry of 1-methylpyrazole. Deuterium, methyl, and fluorine substitution

“…Thus, 3-fluoro-l-methylpyrazole (26) and 4-fluoro-l-methylpyrazole (27) were each observed to phototranspose to a single primary product, 2-fluoro-1-methylimidazole (29) and 4-fluoro-1-methylimidazole (30), respectively. Photolysis of 5-fluoro-1-methylpyrazole (28) was accompanied by formation of two phototransposition products, 5-fluoro-l-methylimidazole (31) and 2fluoro-l-methylimidazole (29) in a ratio of 9.1:1.0. Both products were detected by GLC after 5 min of irradiation, and the concentration vs irradiation time profile confirms that they are both primary products.…”

“…GLC analysis of the irradiated solution showed the formation of 4-fluoro-l-methyl-imidazole (30) with a relative retention of 2.7. 5-Fluoro-l-methylpyrazole (28). GLC analysis of the irradiated solution showed the formation of 2-fluoro-l-methylimidazole (29) and 5-fluoro-l-methylimidazole (31) with relative retentions of 3.2 and 3.7, respectively.…”

Synthesis of 3- and 5-azidopyrazoles

“…У цій праці описано метод синтезу 3-та 5-азидопіразолів з використанням діазосолей на основі 3-та 5-амінопіразолів. Вихідні 3-та 5-амінопіразоли ми отримали взаємодією заміщених гідразинів з акрилонітрильними похідними згідно з описаними методиками [8][9][10].…”

“…1-Алкіл-3-амінопіразоли 1а-в синтезували за методикою [8], 3-амінопіразоли 1г-є -за методикою [9], 5-амінопіразоли 2а-г -за методикою [10], 5-аміно-1-арил-3метилпіразоли 7а-в -за методикою [11].…”

New synthesis of 3-aryl-5-amino-1H-pyrazoles

“…β-Oxo nitriles are prepared in turn by reaction of halo ketones with sodium or potassium cyanide. Other known methods for the preparation of aminopyrazoles are based on intramolecular cyclization of acetophenone thiosemicarbazones [6] and semicarbazones [7,8], reaction of β-amino-β-arylacrylonitrile [9] or α,β-dichloropropionitrile [10] with hydrazines, and decarboxylation of 5-amino-3-arylpyrazole-1-carboxylic acids [3]. Hartmann and Liebscher [5] proposed a procedure for the synthesis of aminopyrazoles via reaction of hydrazine with β-aryl-β-chloroacrylonitriles.…”