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Condensation of ethyl 3-aminopyrazole-4-carboxylate (1) with ethyl ethoxymethylenecyanoacetate (2) was carried out with the aim of preparing diethyl 7-aminopyrazolo[1,5-a]pyrimidine-3,6-dicarboxylate (3) and subsequent study of its C-C recyclization [1] to the isomeric 6-carbamoyl-7-hydroxypyrazolopyrimidine but the reaction did not go to completion. From 1 H NMR spectra (including experiments using the NOESY method) it was clear that a mixture of compounds including both the cyclization product 3 and the uncyclized condensation adduct ethyl 3-[(2-cyano-3-ethoxy-3-oxoprop-1-en-1-yl)amino]-1H-pyrazole-4-carboxylate (4) had been obtained. However, in basic medium both the condensed pyrazolopyrimidine 3 and the cyano derivative 4 were readily converted in high yield to the 6-carbamoyl-7-hydroxypyrazolo[1,5-a]pyrimidine-3-carboxylic acid (5). CO 2 H 1 2 4 3 5 NaOHBearing in mind that the starting 3-aminopyrazole 1 is synthesized by reaction of hydrazine with the same ethoxymethylenecyanoacetate ester 2 [2] we believed that compound 5 could be prepared directly by

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