Hydrochloric Acid → Ethyl 2'-iodo-4'-oxo-5',7'-dihydro-4'H-spiro[cyclopropane-1,6'-pyrazolo[1,5-a]pyrazine]-3'-carboxylate

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Reaction Steps

To a stirred solution of Intermediate 350A (2.1 g, 4.14 mmol) in 1,4-dioxane (10.0 mL) was added 4 M HCl in dioxane (10 mL, 41 mmol) and the resulting solution stirred at RT for 1 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 350B as a pale yellow solid (1.1 g, 60%). MS(ES): m/z=362 [M+H]+; 1H NMR (400 MHz, chloroform-d) δ ppm 6.93 (s, 1H), 4.41 (q, J=7.0 Hz, 2H), 4.26 (s, 2H), 1.41 (t, J=7.0 Hz, 3H), 1.11-0.85 (m, 4H).

Provenance & Evidence