ethyl 5-chloro-4-ethyl-1H-iMidazole-2-carboxylate synthesis

Yield:1171124-66-5 45%

Reaction Conditions:

Stage #1: ethyl 5-ethyl-1H-imidazole-2-carboxylatewith N-chloro-succinimide in chloroform at 20; for 28 h;
Stage #2: with sodium hydrogencarbonate in chloroform;water;

Steps:

1.1c

(1c) Ethyl 4-chloro-5-ethyl-1H-imidazole-2-carboxylate NCS (3.15 g, 23.59 mmol) was added to a solution of ethyl 5-ethyl-1H-imidazole-2-carboxylate obtained in Example (1b) (3.35 g, 19.92 mmol) in chloroform (100 mL), and the mixture was stirred at room temperature for 28 hours. Saturated aqueous sodium bicarbonate solution was added to the reaction solution, followed by extraction with chloroform. Then, the organic layer was washed with brine and dried over anhydrous sodium sulfate. Following concentration under reduced pressure, the residue was purified by silica gel column chromatography (elution solvent: hexane/ethyl acetate = 4/1, 3/1) to obtain 1.81 g of the title compound as a pale yellow solid (45%). ¹H NMR spectrum (400 MHz, CDCl₃) δ ppm: 1.27 (3H, t, J = 7.61 Hz), 1.41 (3H, t, J = 7.12 Hz), 2.71 (2H, q, J = 7.61 Hz), 4.42 (2H, q, J = 7.12 Hz), 10.46 (1H, s).

References:

EP2226322,2010,A1 Location in patent:Page/Page column 28