Lithium Hydroxide → [2-(2-tert-Butylphenoxy)pyridin-3-yl]boronic acid

Participants

Reaction Conditions

Reaction Steps

To a solution of 141a (3.35 g, 9.49 mmol) in THF (60 ml) under nitrogen at −78° C. was added 2.0 M nBuLi in pentane (14.2 mL, 28.47 mmol, 3 eq) over ˜3 min. The reaction was stirred at −78° C. for 10 min & then B(OiPr)3 (6.54 mL, 28.47 mmol, 3 eq) was added in a single aliquot. The reaction was stirred at −78° C. for 40 min and then the reaction was poured into water (˜60 mL) followed by the addition of LiOH (˜3.5 g). The reaction was stirred for 2 h at rt. Partition the reaction mixture between water (˜200 mL additional) and EtOAc (˜200 mL). Separate layers and wash the aqueous once more with EtOAc. Pour aqueous into a large erlenmyer flask & add EtOAc (˜200 mL). With vigorous stirring add conc. HCl dropwise until pH ˜2. Separate layers in sep. funnel & extract aqueous once more with EtOAc (˜200 mL). Combine these last two EtOAc extracts, dry over sodium sulfate, filter and concentrate. Azeotrope twice with toluene to give 234b (2.38 g) as a white solid. 1H NMR (400 MHz, CDCl3) δ ppm 1.31 (s, 9H); 4.1 (bs, 1H); 5.61 (bs, 1H); 6.91 (d, J=7.47 Hz, 1H); 7.05 (dd, J=6.37, 3.74 Hz, 1H); 7.15-7.3 (m, 2H); 7.48 (dd J=7.47, 1.32 Hz, 1H); 8.23 (bs, 1H); 8.27 (dd, J=7.03 Hz, 1H).

Provenance & Evidence