Lithium Hydroxide → 7-methoxy-1-(tetrahydro-2H-pyran-2-yl)-1H-indazole-5-carboxylic acid

Participants

Reaction Steps

To a solution of ethyl 7-methoxy-1-(tetrahydro-2H-pyran-2-yl)-1H-indazole-5-carboxylate (102 mg, 0.33 mmol) in tetrahydrofuran (2 mL) was added 1 N aqueous lithium hydroxide (0.67 mL, 0.67 mmol). The reaction was stirred at room temperature overnight. LCMS showed the reaction to be incomplete. Additional lithium hydroxide (0.35 mL, 2 M, 0.7 mmol) was added and the reaction was heated to 40° C. for 1 hour. The reaction was then left stirring at room temperature for 70 hours. The tetrahydrofuran was removed in vacuo and the residue was acidified to pH=4 with 1 N aqueous hydrochloric acid. The solution was extracted with ethyl acetate (3×). The combined organics were washed with brine, dried over sodium sulfate, filtered, and concentrated to give the title compound (84 mg, 91%) as a solid. (M+1-THP) 193.2; 1H NMR (400 MHz, CDCl3, δ): 8.18 (d, J=1.37 Hz, 1H), 8.12 (s, 1H), 7.46 (d, J=1.17 Hz, 1H), 6.26 (dd, J=10.15, 2.54 Hz, 1H), 4.07-4.12 (m, 1H), 4.06 (s, 3H), 3.65-3.81 (m, 1H), 2.54-2.72 (m, 1H), 2.10-2.22 (m, 1H), 2.01-2.10 (m, 1H), 1.71-1.85 (m, 2H), 1.57-1.67 (m, 1H).

Provenance & Evidence