Reaction #56484

Reaction equation

hydrochloric acid

sodium sulfate

HSCH2CO2H

Ethyl 4-(4-oxobutyl)benzoate

1-amino-2-[1-(tetrahydro-2H-pyran-2-yloxy)cyclohexyl]ethane

→

title compound

Yield 32.0%

4-{3-[3-[2-(1-Hydroxycyclohexyl)ethyl]-4-oxo-2-thiazolidinyl]propyl}benzoic Acid

Yield 32.0%

Solvents

methanol

carbon tetrachloride

chloroform

water

Conditions

Workup

1. 1
   workup.STIRRINGStirring
2. 2
   workup.WAITis continued for 2 hours
3. 3
   OtherThe solid is removed by filtration
4. 4
   Washwashed with a small quantity of benzene
5. 5
   workup.ADDITIONThe combined filtrate and washings are diluted with benzene (70 ml.)
6. 6
   Temperaturerefluxed in a Dean-Stark apparatus for 16 hours
7. 7
   Temperatureto cool to room temperature
8. 8
   Washsubsequently washed with diluted hydrochloric acid and 5% sodium bicarbonate
9. 9
   Dryingdried over anhydrous magnesium sulfate
10. 10
    Filtrationfiltered
11. 11
    OtherEvaporation in vacuo
12. 12
    Otheraffords an oil residue which
13. 13
    workup.STIRRINGThe resulting mixture is stirred at ambient temperature for 3 hours
14. 14
    Extractionextracted with ether
15. 15
    ExtractionThe ethereal extract
16. 16
    Washis washed with diluted sodium bicarbonate
17. 17
    Dryingdried over anhydrous magnesium sulfate
18. 18
    Filtrationfiltered
19. 19
    Concentrationconcentrated
20. 20
    Otherto give an oil residue
21. 21
    WashElution with chloroform-methanol (100:1; v:v; 630 ml.)
22. 22
    Othergives impure material
23. 23
    WashFurther elution with the same eluant (300 ml.)

Procedure

Ethyl 4-(4-oxobutyl)benzoate (4.15 g., 18.8 mmol.) is added dropwise to a stirred solution of 1-amino-2-[1-(tetrahydro-2H-pyran-2-yloxy)cyclohexyl]ethane in carbon tetrachloride (1 ml.) maintained at 25° C. The resulting mixture is stirred for 30 minutes before being treated with anhydrous sodium sulfate (4 g.). Stirring is continued for 2 hours. The solid is removed by filtration and washed with a small quantity of benzene. The combined filtrate and washings are diluted with benzene (70 ml.), treated with HSCH2CO2H (1.84 g., 20 mmole.) in one portion, and then refluxed in a Dean-Stark apparatus for 16 hours. The reaction mixture is allowed to cool to room temperature, subsequently washed with diluted hydrochloric acid and 5% sodium bicarbonate, dried over anhydrous magnesium sulfate, and filtered. Evaporation in vacuo affords an oil residue which is dissolved in methanol (50 ml.) plus concentrated hydrochloric acid (0.2 ml.). The resulting mixture is stirred at ambient temperature for 3 hours, diluted with water, and extracted with ether. The ethereal extract is washed with diluted sodium bicarbonate, dried over anhydrous magnesium sulfate, filtered, and concentrated to give an oil residue. The oil residue is then applied to a silica gel column (120 g.) with chloroform. Elution with chloroform-methanol (100:1; v:v; 630 ml.) gives impure material. Further elution with the same eluant (300 ml.) provides the title compound (2.5 g., 5.96 mmol., 32%) as a pale yellow oil, pmr (CDCl3) δ1.38 (3H, t), 3.50 (2H, s), 4.40 (2H, q), 4.72 (1H, m), 7.23 (2 H, d), 8.00 (2H, d).

Source