반응 #58202

반응 방정식

N,4-dimethoxy-N-methylbenzamide

n-butyllithium

2-bromo-5-methoxybenzoic acid

cardice acetone

→

white crystals

수율 64.0%

5-methoxy-2-(4-methoxybenzoyl)benzoic acid

수율 64.0%

용매

THF

hexane

tetrahydrofuran

반응 조건

후처리

1. 1
   기타does not exceed −70° C
2. 2
   workup.ADDITIONAfter the addition
3. 3
   workup.STIRRINGThe reaction medium is stirred at −78° C. for 1 hour
4. 4
   기타the bath of cardice/acetone is then removed
5. 5
   workup.STIRRINGthe reaction medium is stirred
6. 6
   workup.WAITto return gradually to room temperature, for 18 hours
7. 7
   추출extracted with tert-butyl methyl ether
8. 8
   workup.ADDITIONThe aqueous phase containing the carboxylate
9. 9
   추출extracted with dichloromethane
10. 10
    세척The dichloromethane phase is washed with brine
11. 11
    건조dried over anhydrous sodium sulfate
12. 12
    여과filtered
13. 13
    기타evaporated
14. 14
    기타The product is crystallized from isopropyl ether
15. 15
    여과after filtering
16. 16
    기타drying

실험 절차

A solution of 18.5 g (80 mmol) of 2-bromo-5-methoxybenzoic acid in 150 mL of tetrahydrofuran is stirred under nitrogen at −78° C. in a bath of cardice/acetone. 100 mL (160 mmol) of a 1.6M solution of n-butyllithium in hexane are added dropwise over about 1 hour, while taking care to ensure that the temperature does not exceed −70° C. About half way through the introduction, the formation of a beige-coloured precipitate that corresponds to the formation of the lithium carboxylate is noted. After the addition, the mixture is stirred at −78° C. for 1 hour, and a solution of 15.9 g (80 mmol) of N,4-dimethoxy-N-methylbenzamide in 20 mL of THF is added dropwise. The reaction medium is stirred at −78° C. for 1 hour and the bath of cardice/acetone is then removed and the reaction medium is stirred, while allowing the temperature to return gradually to room temperature, for 18 hours. The mixture is hydrolysed with 100 mL of water, basified to pH=12 with 2N NaOH solution and then extracted with tert-butyl methyl ether. The aqueous phase containing the carboxylate is acidified with 5N HCl solution to pH 1 and extracted with dichloromethane. The dichloromethane phase is washed with brine, dried over anhydrous sodium sulfate, filtered and evaporated. The product is crystallized from isopropyl ether; after filtering and drying, 14.6 g of white crystals are obtained (yield=64%).

출처