反应详情

温度

0 °C

To a stirred solution of diisopropylamine (22 ml) in dry tetrahydrofuran (160 ml) cooled to 0° C. under an inert atmosphere was added n-butyl lithium (2.5M, 67 ml) dropwise. The solution was stirred for 30 minutes at 0° C., then added to a solution of methyl 2,6-dichlorobenzoate (26.62 g) in dry tetrahydrofuran (160 ml) cooled to -78° C. under an inert atmosphere. After 1.5 hours at this temperature the mixture was poured onto excess solid carbon dioxide and left to stand overnight. The solvent was evaporated in vacuo and the residue acidified with 2N hydrochloric acid. This was then extracted with ethyl acetate, dried over anhydrous magnesium sulphate and evaporated in vacuo to yield 2,4-dichloro-3-methoxycarbonylbenzoic acid (32.37 g) as a solid, NMR (DMSO D6) δ3.93 (3H,s), 7.70 (1H, d), 7.91 (1H,d).

1. temperaturecooled to -78° C. under an inert atmosphere
2. waitleft
3. waitto stand overnight
4. customThe solvent was evaporated in vacuo
5. extractionThis was then extracted with ethyl acetate
6. dry with materialdried over anhydrous magnesium sulphate
7. customevaporated in vacuo