Reaction #8658

Reaction equation

Ethyl (2R/S) (+/−) 2-ethoxy-3-(4-hydroxyphenyl)propanoate

NaOH

→

(2S)-2-Ethoxy-3-(4-hydroxyphenyl)propanoic acid

Yield 40.8%

Solvents

phosphate

Conditions

Workup

1. 1
   Other100 mg of the lyophilised esterase preparation from Aspergillus oryzae
2. 2
   workup.ADDITIONwas added
3. 3
   OtherMost of the water was evaporated in vacuo
4. 4
   workup.ADDITIONMethanol was added to the remaining slurry in order
5. 5
   Otherthe hydrolysis
6. 6
   OtherThe precipitate, which formed
7. 7
   Filtrationwas filtered off
8. 8
   Otherthe methanol was evaporated in vacuo
9. 9
   workup.DISSOLUTIONThe remaining oil was dissolved in water
10. 10
    Extractionfollowed by extraction of unreacted ester with tert-butyl methyl ether (TBME) (eeester=87%, determined as in Example 2)
11. 11
    Extractionthe acid extracted with TBME
12. 12
    DryingAfter drying over Na2SO4 and evaporation of the TBME

Procedure

Ethyl (2R/S) (+/−) 2-ethoxy-3-(4-hydroxyphenyl)propanoate (5 g) was added to an aqueous 0.1 M phosphate buffer pH 7 (10 ml). 100 mg of the lyophilised esterase preparation from Aspergillus oryzae was added and the mixture was stirred for 18 hours at room temperature. During that time, the pH of the reaction mixture was kept constant at pH=6-8 by addition of NaOH. Most of the water was evaporated in vacuo. Methanol was added to the remaining slurry in order to stop the hydrolysis. The precipitate, which formed was filtered off and the methanol was evaporated in vacuo. The remaining oil was dissolved in water followed by extraction of unreacted ester with tert-butyl methyl ether (TBME) (eeester=87%, determined as in Example 2). The water phase was acidified to pH=3 and the acid extracted with TBME. After drying over Na2SO4 and evaporation of the TBME, 1.8 g (2S)-2-Ethoxy-3-(4-hydroxyphenyl)propanoic acid was obtained as an oil, which crystallized on standing (m.p.=105° C., eeacid=>99%, determined as in Example 2).

Source