General procedure for the synthesis of benzo[c][1,2]oxaborolane-1,6(3H)-diol from 6-(benzyloxy)benzo[C][1,2]oxaborolane-1(3H)-ol: 6-(benzyloxy)benzo[C][1,2]oxaborolane-1(3H)-ol (13 mmol) was dissolved in methanol (300 mL). To this solution was added 10% palladium/carbon catalyst (200 mg) under nitrogen protection. The reaction mixture was evacuated under vacuum three times and charged with hydrogen, followed by stirring the reaction overnight at room temperature. Upon completion of the reaction, the catalyst was removed by filtration and the filtrate was concentrated by rotary evaporation. The residue was purified by recrystallization to afford benzo[c][1,2]oxaborolane-1,6(3H)-diol (1.98 mg, 98% yield). The product was characterized by 1H NMR (300 MHz, DMSO-d6): δ 9.29 (s, 1H), 9.04 (s, 1H), 7.18 (d, J=8.4Hz, 2H), 6.87 (dd, J=8.1, 2.4Hz, 1H), 4.86 (s, 2H) ppm. melting point was 133-135 °C.
![benzo[c][1,2]oxaborole-1,6(3H)-diol](/CAS/20150408/GIF/1196473-37-6.gif)