反应详情

(The following reaction is carried out in an anhydrous N2 atmosphere.) Dissolve thiophene-2-yl-acetic acid methyl ester (42) (2.0 g, 12.8 mmol) in anhydrous chloroform (9.0 mL) and glacial acetic acid (9.0 mL), add N-bromosuccinimide (2.3 g, 13.0 mmol) in portions and stir the mixture for 3 d at rt. Add water to the reaction mixture, separate layers and extract the aqu. layer with dichloromethane. Wash combined organic layer several times with a 1 M aqu. NaOH and water and once with brine and dry it with Na2SO4. Purify the crude product by preparative radial chromatography (CyH/EtOAc 5+1] to obtain (5-bromo-thiophen-2-yl)-acetic acid methyl ester (43) as a yellow oil (2.46 g, 81%) which is used without any further purification. 1H NMR (400 MHz, CDCl3): 3.71 (s, 3H); 3.75 (s, 2H); 6.67 (d, 1H, J=3.8 Hz); 6.88 (d, 1H, J=3.8 Hz).

1. custom(The following reaction
2. customAdd water to the reaction mixture, separate layers
3. extractionextract the aqu
4. washWash
5. dry with materialNaOH and water and once with brine and dry it with Na2SO4
6. customPurify the crude product by preparative radial chromatography (CyH/EtOAc 5+1]