Sodium Hydroxide → 2-(1-carboxy-3-phenylpropylamino)-hexahydro-3-oxo-1H-pyrazolo[1,2-a]pyridazine-5-carboxylic acid

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Reaction Steps

0.896 g of 2-amino-hexahydro-3-oxo-1H-pyrazolo[1,2-a]pyridazine-5-carboxylic acid (racemate A) was dissolved in 6 ml of water. 2.4 g of 2-oxo-4-phenylbutyric acid were added and the mixture was adjusted to pH 6 with 2N aqueous sodium hydroxide solution. 0.504 g of sodium cyanoborohydride was then added and the mixture was stirred at room temperature for 22 hours. The resulting solution was applied to 10 g of Zerolit 225 ion-exchange resin (H+ form). Elution with water containing 2% pyridine gave 0.98 g of a crude diastereomeric product. Crystallization from water gave a solid which was recrystallized from methanol to yield 0.36 g (22%) of 2-(1-carboxy-3-phenylpropylamino)-hexahydro-3-oxo-1H-pyrazolo[1,2-a]pyridazine-5-carboxylic acid (racemate A) in the form of a white solid of melting point 233°-235° C. (decomposition).

Provenance & Evidence