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Paper | Regular issue | Vol 53, No. 6, 2000, pp.1285-1292
Published online, 1st January, 1970
DOI: 10.3987/COM-00-8871
Chemoselective Synthesis of 3- and 5-Pyrazolylacetates

Chiara B. Vicentini, Maurizio Manfrini, Manuela Mazzanti, Monica Manferdini, Carlo F. Morelli, and Augusto C. Veronese*

*Dipartimento di Scienze Farmaceutiche-Università di Ferrara, via Fossato di Mortara 17, I-44100, Ferrara, Italy


Methyl 3,5-dioxohexanoate (1) reacts with hydrazines (2) in methanol or acetic acid to give a mixture of the isomeric pyrazolylacetates (3) and (4), whose molar ratio depends on the solvent and hydrazine. 2,2-Dimethyl-5-(1-hydroxy-3-oxobutylidene)-1,3-dioxane-4,6-dione (5) reacts chemoselectively with hydrazines to give the 5-pyrazolylacetates (3) as the only reaction products.