反应详情

Preferred reaction solvents are alcohols selected from methanol, ethanol, 1-propanol and 2-propanol. Preferred reaction temperatures are in the range of about 15-40° C. Especially preferred is the alkali metal hydroxide, potassium hydroxide (85% w/w) in reaction solvent 2B (anhydrous) ethanol in the temperature range of about 15-30° C. Said especially preferred method is used for the preparation of the especially preferred, potassium salt of 5,6-dihydro-4H-pyrrolo[1,2-b]pyrazole-2-carboxylate, using a ratio in the range of about 1.5:1 to about 2.5:1 mixture of the ethyl esters, ethyl 5,6-dihydro-4H-pyrrolo[1,2-b]pyrazole-2-carboxylate and ethyl 5,6-dihydro-4H-pyrrolo[1,2-b]pyrazole-3-carboxylate, respectively. The product, potassium 5,6-dihydro-4H-pyrrolo-[1,2-b]pyrazole-2-carboxylate, is obtained in at least 81% yield (after a reaction time of about 4-7 hours at about 15-22° C.). However, if impurities (such as potassium 5,6-dihydro-4H-pyrrolo-[1,2-b]pyrazole-3-carboxylate) are present they may optionally be removed by slurrying in 2B ethanol (anhydrous).

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