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

Temperature

-70 °C

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%).

1. temperatureto warm to −20° C
2. extractionextracted with Et2O (2×50 mL)
3. additionThe pH of the water phase was then adjusted to about pH 7 by the addition of NaOH (5 M aq. solution)
4. additionBrine was added
5. extractionthe product was extracted with EtOAc (4×50 mL)
6. customRemoval of the solvent

ORD record

ord-1c42fefef91343c6a9611a03bff94a16

Source dataset

uspto-grants-2010_04

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07705023B2