Hydrochloric Acid → 4H,5H,6H-pyrrolo[1,2-b]pyrazole-2-carboxylic acid

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Reaction Conditions

Reaction Steps

A 25-mL round-bottomed flask equipped with a reflux condenser was charged with ethyl 5,6-dihydro-4H-pyrrolo[1,2-b]pyrazole-2-carboxylate (540 mg, 3.0 mmol), 2N Aqueous sodium hydroxide solution (3.5 mL), and 1,4-dioxane (3.0 mL). The system was heated at 65° C. for 2.5 h. It was then cooled to room temperature and adjusted the pH to 2-3 with concentrated HCl. The solid was collected by filtration to afford 162a (260 mg, 57%) as a yellow solid. MS-ESI: [M+H]+ 153.3

Provenance & Evidence