反应详情

5-Methyl-thiophene-2-carboxylic acid methyl ester (20.0 g, 0.13 mol) was dissolved in a suspension of N-bromosuccinimide (45.4 g, 0.26 mol) and 2,2′-aza-bis-isobutyronitrile (0.1 g, 0.61 mmol) in 1 L of carbon tetrachloride. The suspension was refluxed for 48 hours then cooled and the precipitate was filtered off. The filtrate was concentrated and the residue was purified on silica gel (100% hexanes then 9:1 Hexanes-Ethyl acetate) to provide a 26 g fraction containing mainly the di-brominated compound 5-dibromomethyl-thiophene-2-carboxylic acid methyl ester as a yellow oil and a more polar fraction (7.5 g) containing mainly compound T-1 (25% yield) as a yellow oil (70% purity).

1. temperatureThe suspension was refluxed for 48 hours
2. temperaturethen cooled
3. filtrationthe precipitate was filtered off
4. concentrationThe filtrate was concentrated
5. customthe residue was purified on silica gel (100% hexanes
6. custom9:1 Hexanes-Ethyl acetate) to provide a 26 g fraction
7. additiona more polar fraction (7.5 g) containing mainly compound T-1 (25% yield) as a yellow oil (70% purity)