反应详情

温度

-70 °C

39.5 g of N,N-dimethyl-2-methoxy-benzamide and 28.5 ml of tetramethylethylenediamine are introduced into 190 ml of absolute tetrahydrofuran and the mixture is lithiated at -70° C. with 150 ml of a 1.4-molar sec-butyllithium solution in cyclohexane/isopentane. After subsequently stirring at -70° C. for 45 minutes, 25.6 ml of ethyl bromide are added dropwise within 25 minutes and the reaction mixture is then allowed to warm slowly to room temperature. Water is then added and the mixture is adjusted to pH 2 with hydrochloric acid and extracted twice with diethyl ether. The residue is purified on silica gel using ethyl acetate/n-hexane (4:6) to yield 6-ethyl-N,N-dimethyl-2-methoxy-benzamide in the form of a colourless oil, 1H-NMR (CDCl3): 3.82 ppm (m), 3.40 ppm (m) and 3.12 ppm (2q, N(CH2CH3)2), 2.56 ppm (m, CH2CH3).

1. temperatureto warm slowly to room temperature
2. extractionextracted twice with diethyl ether
3. customThe residue is purified on silica gel