Cyanoacetic esters reaction with hydrazines

Like / -keto esters, /3-keto nitriles react smoothly with hydrazine the latter give aminopyrazoles.78,310-321 Under the same conditions cyanoacetic ester and its derivatives give aminopyrazolones.322-325 The reaction of malononitrile is more complex, giving 1-substituted 3-cyanomethyl-4-cyano-5-aminopyrazole and products formed by further condensation.328... 

From ethyl 2-cyanoacetate. 5-Aminopyrazol-3-ones can be conveniently prepared from /7-keto esters with hydrazines. Thus, heating ethyl 2-cyanoacetate 142 with (4-ferf-butylphenyl)hydrazine 143 in ethanolic sodium ethoxide afforded 5-amino-2-(4-ferf-butylphenyl)-2,4-dihydropyrazol-3-one 144 (01JMC3730) (Scheme 33). The reaction that takes place under acidic conditions, between ethyl 2-cyanoacetate 142 and 2-hydrazino-6-oxopyrimidine-5-carbonitrile 145 in boiling acetic... 

A 100 mL flask was charged with hydrazine (1 1 mmol), p-keto ester (2 1 mmol), isatin (3 1 mmol) and malononitrile/ethyl cyanoacetate (4 1 mmol) and piperdine (20 mol%, 0.2 mmol) in ethanol (15 mL). The mixture was sonicated in the water bath of an ultrasonic cleaner (power 250 W irradiation frequency 40 kHz) at room temperature (25 30 °C). After the completion of the reaction (monitored by TLC), the resulting precipitate was filtered and washed with ethanol to afford the pure product of spiro[indoline-3,4 -pyrano[2,3-c]pyrazole] 5 as solid in good to excellent yields. Each of the products was characterized by IR, NMR, C-NMR and HRMS studies. 

In addition, 12 was reported to be a suitable organocatalyst for other reactions, including amination of a-cyanoacetates or P-carbonyl esters by reaction with azodi-carboxylate followed by nitrogen-nitrogen bond cleavage of the resultant hydrazine [51]. Recently, a P-isocupreidine with a biphenyl group at C6 instead of a hydroxyl functionality was reported to catalyze the enantioselective [4-1-2] annulation of substituted chromone-3-carbaldehydes and related imines (Scheme 6.22) [52]. 

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