Hydrochloric Acid → Ethyl 2-iodo-6-methyl-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 340A (7.0 g, 14.13 mmol) in 1,4-dioxane (10 mL) was added 4 M HCl in dioxane (25 mL, 100 mmol) and the solution was stirred at RT for 2 h. The reaction mixture was concentrated and the residue was diluted with EtOAc (20 mL). The EtOAc solution was washed successively with water, a saturated aq. solution of NaHCO3, and brine. The organic layer was dried over Na2SO4, filtered and concentrated under reduced pressure. The residue obtained was heated in a ROTAVAPOR® at 60° C. for 5 h. The solid product was washed with ether to afford Intermediate 340B (4.0 g, 87%). MS(ES): m/z=350 [M+H]+; 1H NMR (300 MHz, DMSO-d6) δ ppm 8.49 (s, 1H), 4.27-4.49 (m, 1H), 4.11-4.26 (m, 2H), 4.03 (d, J=11.71 Hz, 2H), 1.06-1.39 (m, 6H).

Provenance & Evidence