Abstract
An analytical solution for the dynamic kinetic resolution of enzyme-catalyzed irreversible acyl transfer was employed to study the side-reaction effects on the yield and optical purity of the desired enantiomeric product. A lipase-catalyzed enantioselective thiotransesterification between (R,S)-naproxen 2,2,2-trifluoroethyl thioester and 4-morpho-line ethanol with in situ racemization of (R)-thioester using trioctylamine as the racemization catalyst in isooctane was designed as a model system to compare the theoretical predictions. Under an initial water activity of 0.113, adding trioctylamine was found to have profound effects on the hydrolysis side-reactions, thus enhancing the chemoselectivity of the lipase to the alcohol in comparison with water. Theoretical analysis also indicated that the time-course yield and the enantiomeric excess for the desired enantiomer could be improved if the employed lipase had higher activity and enantioselectivity for the hydrolysis and esterification side-reactions, especially when the base had a similar racemization rate compared with the rate of the fast-reaction substrate.
| Original language | English |
|---|---|
| Pages (from-to) | 457-469 |
| Number of pages | 13 |
| Journal | Journal of the Chinese Institute of Chemical Engineers |
| Volume | 34 |
| Issue number | 4 |
| State | Published - 07 2003 |
| Externally published | Yes |
Keywords
- (S)-Naproxen ester
- Dynamic kinetic resolution
- Esterification
- Hydrolysis
- Lipase
- Thiotransesterification