Reaction #5361

Reaction equation

HCl

1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride

4-(chlorophenoxy]pentanoic acid

thiotetronic acid

triethylamine

dimethylformamide

→

4-hydroxy-3-[5-(4-chlorophenoxy)-1-oxopentyl]-2(5H)-thiophenone

Yield 24.0%

Conditions

Workup

1. 1
   Extractionextracted three times with ether
2. 2
   DryingThe combined organic layers are dried over Na2SO4
3. 3
   Concentrationconcentrated in vacuo
4. 4
   Othergiving a yellow solid
5. 5
   OtherThe residue is recrystallized from ethyl acetate/hexane at -78° C.

Procedure

To a stirring solution of 224 mg (1.89 mmol) of thiotetronic acid in 10 mL of dimethylformamide is added 290 μL (2.08 mmol) of triethylamine and 77 mg (631 μmol) of 4-dimethylaminopyridine at 0° C. Next, 440 mg (2.29 mmol) of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 530 mg (2.32 mmol) of 5-[4-(chlorophenoxy]pentanoic acid are added and the reaction mixture is stirred overnight at room temperature. The reaction is acidified with 1.0N HCl and extracted three times with ether. The combined organic layers are dried over Na2SO4 and concentrated in vacuo giving a yellow solid. The residue is recrystallized from ethyl acetate/hexane at -78° C. to give 150 mg (24%) of 4-hydroxy-3-[5-(4-chlorophenoxy)-1-oxopentyl]-2(5H)-thiophenone.

Source