N-bromobutanimide → Ethyl 5-bromo-2-(pyridin-3-yl)thiazole-4-carboxylate

Beteiligte Stoffe

Reaktionsschritte

A tetrahydrofuran (15 mL) solution of ethyl 2-(pyridin-3-yl)thiazole-4-carboxylate (1.17 g, 5.0 mmol) was added to −78° C. solution of potassium bis(trimethylsilyl)amide (12 mL, 6 mmol, 0.5 M in toluene) over 2 min. This reaction mixture was allowed to stir for 1.5 h and then was transferred via canula into a −78° C. solution of N-bromosuccinimide (1.35 g, 7.5 mmol) in tetrahydrofuran (5 mL). This mixture was stirred for 5 min and then the reaction vessel was removed from the cooling bath and allowed to warm to room temperature over 3 h. The reaction was quenched by pouring into a mixture of ether and water. The layers were separated and the aqueous layer was extracted twice with ethyl acetate. The combined organics were dried over MgSO4, filtered, and the solvent was removed in vacuo. The residue was subjected to silica gel chromatography (0 to 100% ethyl acetate/hexanes) to give the desired product as a white solid (824 mg, 52%): 1H NMR (300 MHz, CDCl3) δ 9.09 (d, J=2.3 Hz, 1H), 8.71 (dd, J=4.9, 1.3 Hz, 1H), 8.25 (dt, J=8.2, 1.7 Hz, 1H), 7.41 (dd, J=7.9, 4.9 Hz, 1H), 4.48 (q, J=7.3 Hz, 2H), 1.46 (t, J=7.3 Hz, 3H); ESIMS m/z 315.0 (M+2).

Herkunft & Nachweise