Sodium Bicarbonate → 3-bromo-2-pyridin-2-yl-5,6-dihydro-4H-pyrrolo[1,2-b]pyrazole

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Reaction Steps

Stir a mixture of 2-(pyridin-2-yl)-5,6-dihydro-4H-pyrrolo[1,2-b]pyrazole-3-carboxylic acid (Preparation 2C; 2 g, 8.7 mmol), sodium bicarbonate (3.3 g, 38.4 mmol), and N-bromosuccinamide (1.7 g, 9.6 mmol) in DMF (50 mL) at room temperature for 2 h. Dilute the crude mixture with water (50 mL) and ethyl acetate (100 mL). Separate the ethyl acetate layer, extract with saturated sodium chloride solution, dry over anhydrous sodium sulfate, filter, and evaporate to a solid mass. Purify by MPLC (SiO2, 1:1 ethyl acetate/hexane) to obtain 1.62 g (70%) of the title compound as a cream solid. MS (ES) m/z 264 (M+H).

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