Hydrazine hydrate (1:1) → ethyl 5-(1,3-thiazol-2-yl)-1H-pyrazole-3-carboxylate

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Reaction Steps

A mixture of 2,4-diketo-4-(thiazol-2-yl)butyric acid ethyl ester (9.88 g), hydrazine hydrate (1.74 g), and ethanol (25 ml) was refluxed for one hour, concentrated and the residue chromatographed (silica gel, EtOAc/Hex 1/2) to afford 2.58 g of 5-(thiazol-2-yl)pyrazole-3-carboxylic acid ethyl ester. NMR: 1.42 (t, 3H), 4.44 (q, 2H), 7.37 (s, 1H, 4-pyrazolyl H), 7.40, 7.75 (2d, 2H, thiazolyl H's).

Provenance & Evidence