Hydrochloric Acid → Tavaborole

Beteiligte Stoffe

Reaktionsschritte

To a solution of 5b (73.2 g, 293 mmol) in dry THF (400 mL) was added n-butyllithium (1.6 M in hexanes; 200 mL) over 45 min at −78° C. under nitrogen atmosphere. Anion precipitated. After 5 min, (i-PrO)3B (76.0 mL, 330 mmol) was added over 10 min, and the mixture was allowed to warm to room temperature over 1.5 h. Water and 6 N HCl (55 mL) were added, and the solvent was removed under reduced pressure to about a half volume. The mixture was poured into ethyl acetate and water. The organic layer was washed with brine and dried over anhydrous Na2SO4. The solvent was removed under reduced pressure. To a solution of the residue in tetrahydrofuran (360 mL) was added 6 N HCl (90 mL), and the mixture was stirred at 30° C. overnight. The solvent was removed under reduced pressure to about a half volume. The mixture was poured into ethyl acetate and water. The organic layer was washed with brine and dried over anhydrous Na2SO4. The solvent was removed under reduced pressure, and the residue was treated with i-Pr2O/hexane to give 19b (26.9 g, 60%) as a white powder: mp 118-120° C.; 1H NMR (300 MHz, DMSO-d6) δ (ppm) 4.95 (s, 2H), 7.15 (m, 1H), 7.24 (dd, J=9.7, 1.8 Hz, 1H), 7.74 (dd, J=8.2, 6.2 Hz, 1H), 9.22 (s, 1H); ESI-MS m/z 151 (M−H)−; HPLC purity 97.8%; Anal (C7H6BFO2) C, H.

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