Reaction #1435678

Reaction equation

sodium sulfide nonahydrate

methyl 2,3-diaminobenzoate

N-acetylpiperidine-4-carbaldehyde

hydrochloricacid

→

product

Yield 75.0%

Methyl 2-(N-acetylpiperidin-4-yl)benzimidazole-4-carboxylate

Yield 75.0%

Solvents

water

water

water

methanol

methanol

Conditions

Workup

1. 1
   workup.ADDITIONwere added dropwise
2. 2
   Temperaturethe whole was refluxed for 30 minutes
3. 3
   TemperatureAfter cooling
4. 4
   Temperaturethe whole was again refluxed
5. 5
   workup.ADDITIONwere then added dropwise
6. 6
   workup.WAITthe whole was boiled for a further 10 minutes
7. 7
   TemperatureAfter cooling
8. 8
   Otherthe reaction solution was evaporated down under reduced pressure
9. 9
   OtherThe residue obtained
10. 10
    Filtrationfiltered
11. 11
    Extractionwas extracted several times with ethyl acetate
12. 12
    WashThe combined organic phases were washed with water
13. 13
    Otherdried
14. 14
    Otherevaporated down under reduced pressure

Procedure

3.3 g (19.9 mmol) of methyl 2,3-diaminobenzoate were dissolved in 100 ml of methanol, and a solution of 4.0 g (25.8 mmol) of N-acetylpiperidine-4-carbaldehyde in 100 ml of methanol was added dropwise at room temperature. The whole was stirred for about 10 minutes at room temperature. Thereafter, 5.2 g (25.8 mmol) of copper(II) acetate, which was dissolved in 100 ml of water, were added dropwise and the whole was refluxed for 30 minutes. After cooling, 25 ml of concentrated hydrochloricacid were added carefully and the whole was again refluxed. 7.15 g (29.8 mmol) of sodium sulfide nonahydrate, dissolved in 100 ml of water, were then added dropwise and the whole was boiled for a further 10 minutes. After cooling, the reaction solution was evaporated down under reduced pressure. The residue obtained was dispersed in water and filtered. The filtrate was rendered alkaline with aqueous sodium bicarbonate solution and was extracted several times with ethyl acetate. The combined organic phases were washed with water, dried and evaporated down under reduced pressure. 4.5 g of the product were obtained.

Source