Hydrochloric Acid → 3,5-Dimethylphenylboronic acid

Participants

Reaction Steps

Magnesium turnings (1.44 g, 59.43 mmol) were covered with dry THF (18.8 mL) in a dried, nitrogen filled flask fitted with an addition funnel and reflux condenser. To this was added 5-bromo-m-xylene (10 g, 54.03 mmol) in THF (15 mnL) after initiation of the Grignard reaction. The addition was carried out over several minutes and the reacton mixture was heated at reflux for 1-2 hours until most of the magnesium had reacted. The reaction mixture was then cooled and transferred to an addition funnel fitted to an nitrogen filled flask containing triisopropyl borate (24.9 mL) at −70° C. The dropwise addition was carried out over several minutes and the mixture warmed to room temperature and stirred overnight. The grey solution was poured onto 2 M HCl and immediately turned yellow. The solution was extracted with Et2O and the Et2O fractions were combined, dried over MgSO4 and the solvent was removed in vacuo to provide the desired product (2.41 g): m.p.249-251° C.; 1H NMR (CDCl3) d 2.44 (6H, s), 7.23 (1H, s), 7.84 (2H, s); 13C NMR (CD3OD) d 21.36, 133.28, 134.39, 137.48.

Provenance & Evidence