Use of the α-amination reaction for the synthesis of pyrazole derivatives containing carbo- and heterocyclic substituents on the nitrogen atom
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A method has been developed for the synthesis of pyrazoles with carbo- and heterocyclic substituents on the nitrogen atom based on the α-amination reaction of carbo- and heterocyclic ketones, using azodicarboxylate–L-proline system with subsequent interaction with malonodialdehyde tetramethyl-acetal. In the case of carbocyclic ketones and tetrahydro-γ-pyranone, the reaction occurs stereo-selectively to give chiral hydrazines and pyrazoles. With derivatives of piperidin-4-one, α-amination is accompanied by racemization.
Keywordsazodicarboxylate cyclohexanone cyclopentanone N-substituted piperidones pyrazoles L-proline tetrahydro-γ-pyranone stereoselective α-amination
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