Réaction #81098

Équation de réaction

cis-2-aminocyclohexanol

racemic trans-2-benzamidocyclohexanol

H2SO4

NaOH

→

cis-2-benzamidocyclohexanol

Rendement 33.0%

Solvants

H2O

H2O

Conditions de réaction

Traitement

1. 1
   Températurethe mixture was heated
2. 2
   Températureunder reflux for 15 hours
3. 3
   Lavagewashed with 20mL of methylene chloride
4. 4
   AutreThe acidic aqueous phase was separated
5. 5
   Extractionthe mixture extracted with a total of 60 mL of methylene chloride at 30°-35° C
6. 6
   SéchageThe combined extracts were dried over anhydrous Na2SO4
7. 7
   Filtrationfiltered
8. 8
   ConcentrationThe filtrate was concentrated in vacuo
9. 9
   Autreto provide crude product
10. 10
    Autrewas isolated
11. 11
    Autrepurified by flash chromatography on silica gel with ethyl acetate-hexane (1:1)

Mode opératoire

A mixture of 24 g (11 mmol) of racemic trans-2-benzamidocyclohexanol and 12 g of 90% H2SO4 (110 mmol) was stirred at 75°-80° for 6 hours. After the addition of 22 mL of H2O, the mixture was heated under reflux for 15 hours. The mixture was cooled to room temperature and washed with 20mL of methylene chloride. The acidic aqueous phase was separated, treated with 12.6 mL of 50% NaOH solution (240 mmol) at <40° C., 30mL of H2O was added and the mixture extracted with a total of 60 mL of methylene chloride at 30°-35° C. The combined extracts were dried over anhydrous Na2SO4 and filtered. The filtrate was concentrated in vacuo to provide crude product containing cis-2-aminocyclohexanol which was isolated and purified by flash chromatography on silica gel with ethyl acetate-hexane (1:1) to provide 792 mg of cis-2-benzamidocyclohexanol (33% of theory). Proton and C13NMR were consistent with the proposed structure.

Source