Hydrochloric Acid → 6-(Cyclopentyloxy)pyridine-3-boronic acid

Participants

Reaction Conditions

Reaction Steps

To a mixture of 5-bromo-2-cyclopentoxypyridine (2.5 g, 10.3 mmol, see step (b) above), B(O-iPr)3 (2.33 g, 13.4 mmol), THF (4.1 mL) and toluene (16.5 mL) was portion-wise-added BuLi (2.5 M in hexane; 4.96 ml, 13.4 mmol) at −70° C. over 1 h. The reaction mixture was stirred over a further 40 min at −70° C. and then allowed to warm to −20° C. The acidity of the reaction mixture was adjusted to about pH 1 by addition of HCl (2 M aq. solution). The reaction was diluted with water (50 mL) and extracted with Et2O (2×50 mL). The pH of the water phase was then adjusted to about pH 7 by the addition of NaOH (5 M aq. solution). Brine was added and the product was extracted with EtOAc (4×50 mL). Removal of the solvent afforded the sub-title compound (0.99 g, 46%).

Provenance & Evidence