Hydrochloric Acid → Ethyl 6-(hydroxymethyl)-2-iodo-4-oxo-4,5,6,7-tetrahydropyrazolo[1,5-a]pyrazine-3-carboxylate

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Reaction Steps

To a solution of Intermediate 351A (3.3 g, 5.99 mmol) in dioxane (10 mL) was added 4 M HCl in dioxane (5 mL, 5.99 mmol) and the resulting reaction mixture was stirred at RT for 3 h. The reaction mixture was concentrated and the crude product was basified with a 10% aqueous solution of sodium bicarbonate and extracted with EtOAc (3×100 mL). The combined organic layer was dried over sodium sulfate, filtered and concentrated slowly (2 to 3 h) using a rotary evaporator at 60° C. to obtain Intermediate 351B (1.6 g, 67.4%) as a white solid. MS(ES): m/z=366 [M+H]+; 1H NMR (400 MHz, DMSO-d6) δ ppm 8.43 (d, J=3.0 Hz, 1H), 5.14 (t, J=5.5 Hz, 1H), 4.46-4.41 (m, 1H), 4.37-4.30 (m, 1H), 4.25 (q, J=7.0 Hz, 2H), 3.84-3.75 (m, 1H), 3.54-3.47 (m, 1H), 3.36 (s, 1H), 1.28 (t, J=7.0 Hz, 3H).

Provenance & Evidence