Potassium Carbonate → 5-(4-Methoxy-2-methyl-phenyl)-4-methyl-thiophene-2-carboxylic acid methyl ester

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

To a mixture of 4-methoxy-2-methylphenylboronic acid (912 mg, 6 mmol), 5-bromo-4-methyl-thiophene-2-carboxylic acid methyl ester (1.1 g, 5 mmol) and K2CO3 (1.38 g, 10 mmol) in toluene (30 mL) and water (5 mL) is bubbled N2 for 15 minutes followed by addition of tetrakis(triphenylphosphine) palladium (289 mg, 0.25 mmol). The mixture is stirred at 80° C. under N2 overnight and filtered through a pad of diatomaceous earth eluting with EtOAc. The combined filtrate is concentrated. The resulting residue is purified by column chromatography (0-15% EtOAc in hexanes) to give 5-(4-methoxy-2-methyl-phenyl)-4-methyl-thiophene-2-carboxylic acid methyl ester (540 mg, 39%). 1H-NMR (CDCl3): δ 7.63 (s, 1H), 7.15 (d, 1H, J=8.4 Hz), 6.82 (d, 1H, J=2.8 Hz), 6.78 (dd, 1H, J=2.8, J=8.4 Hz), 4.79 (bs, 1H), 3.88 (s, 3H), 3.83 (s, 3H), 2.17 (s, 3H), 2.02 (s, 3H).

Herkunft & Nachweise