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

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Reaction Steps

To a stirred solution of Intermediate 348B (8.0 g, 15.34 mmol) in 1,4-dioxane (10.0 mL) was added 4 M HCl in dioxane (40.0 mL, 160 mmol) and the resulting solution stirred at RT for 2 h. The reaction mixture was concentrated and diluted with EtOAc (50 mL). The organic layer was washed successively with water, a saturated aq. solution of NaHCO3, and brine, then dried over Na2SO4, filtered and the filtrate concentrated under reduced pressure. The residue obtained was heated in a ROTAVAPOR® at 60° C. for 5 h. The solid product was triturated with diethyl ether to afford Intermediate 348C as an off-white solid (1.6 g, 28%). MS(ES): m/z=376 [M+H]+; 1H NMR (300 MHz, DMSO-d6) δ ppm 8.67 (d, J=2.27 Hz, 1H), 4.47 (dd, J=13.22, 4.53 Hz, 1H), 4.17-4.33 (m, 3H), 3.15 (d, J=9.07 Hz, 1H), 1.28 (s, 3H), 0.90 (d, J=8.69 Hz, 1H), 0.40-0.54 (m, 2H), 0.20-0.37 (m, 2H).

Provenance & Evidence