Hydrochloric Acid → (R)-2-(6-(5-amino-1,3,4-thiadiazol-2-yloxy)-1-hydroxy-4-methyl-1,3-dihydrobenzo[c][1,2]oxaborol-3-yl)acetic acid

Participants

Reaction Steps

To a solution (R)-ethyl 2-(6-(5-amino-1,3,4-thiadiazol-2-yloxy)-1-hydroxy-4-methyl-1,3-dihydrobenzo[c][1,2]oxaborol-3-yl)acetate (30 g, 86 mmol) in a mixed solution of THF (750 mL) and methanol (100 mL) was added a solution of LiOH.H2O (12.63 g, 301 mmol) in water (750 mL) at 0° C. The resulting mixture was stirred at room temperature for 2 hrs and then acidified to pH=2 with diluted hydrochloric acid at 0° C. After removal of the volatile organics, the residue was dissolved in EtOAc. The aqueous phase was separated and concentrated in vacuo, and the residue was neutralized to pH=6.5˜7.0 using saturated aq. sodium bicarbonate. The precipitated solid was filtered and stirred with EtOAc for 1 hr. The solid was filtered, washed with cold EtOAc and water then dried to give the product (R)-2-(6-(5-amino-1,3,4-thiadiazol-2-yloxy)-1-hydroxy-4-methyl-1,3-dihydrobenzo[c][1,2]oxaborol-3-yl)acetic acid (21 g, 76% yield). 1H NMR (400 MHz, DMSO-d6) δ12.31 (1H, s), 9.26 (1H, s), 7.33 (1H, m), 7.16 (1H, m), 7.06 (2H, s), 5.50 (1H, m), 3.03 (1H, m), 2.29 (3H, s), 2.10 (1H, m). ESI-MS m/z 322 (M+H+, positive); [α]25D=−91.395°±0.305° (C=1.0017 g/100 ml diluted with 2M HCl, L=0.5 dm).

Provenance & Evidence