Trimethyl borate → 2-Formyl-1-methyl-phenylboronic acid

Participants

Reaction Steps

The 1-bromo-3-dimethoxymethyl-2-methyl-benzene ((Example 6: step c) 500 mg, 2 mmol), butyllithium (2.5 M, 1 mL, 2.5 mmol), and trimethylborate (2.3 mL, 20 mmol) were reacted as in Example 5: step b. After aqueous workup, the residue was dissolved in acetone (18 mL) and HCl (1N, 2 mL). After standing for 18 h at rt, the volatile components were removed in vacuo and the residue was purified by SiO2 flash chromatography (25–40% EtOAc in hexanes) to give the title compound (126 mg, 38%). The title compound exists as a mixture of boronic acids and anhydrides in CDCl3, therefore the reported NMR signals represent pairs or groups of related signals. 1H-NMR (CDCl3): δ 10.44 (s, 1H), 8.38 (dd, 1H, J=1.4, 7.4 Hz), 7.49 (t, 1H, J=7.5 Hz), 3.12 (s, 3H).

Provenance & Evidence