Enzymes in organic synthesis, 4. Investigation of the pancreatin-catalyzed acylation of cis-cyclopent-2-ene-1,4-diol with various trichloroethyl and vinyl Alkanoates
✍ Scribed by Theil, Fritz ;Schick, Hans ;Lapitskaya, Margarita A. ;Pivnitsky, Kasimir K.
- Book ID
- 102902336
- Publisher
- John Wiley and Sons
- Year
- 1991
- Tongue
- English
- Weight
- 668 KB
- Volume
- 1991
- Category
- Article
- ISSN
- 0947-3440
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✦ Synopsis
Abstract
During the pancreatin‐catalyzed acetylation of the meso‐diol 1 with 2,2,2‐trichloroethyl acetate (2a) in tetrahydrofuran/tri‐ethylamine, the enantiomeric monoacetates 3a and ent‐3a are formed at nearly equal rates. ent‐3a is rapidly acetylated in a second enzyme‐catalyzed step, forming 4a, whereas 3a resists further enzymatic acetylation. Thus, the monoacetate 3a can be obtained in 48% yield with an enantiomeric excess (e.e.) of more than 99%. 2,2,2‐Trichloroethyl propanoate and butanoate give the corresponding monoacylation products even in slightly better yield, whereas the octanoate affords the mono‐acylation product with a lower enantiomeric excess. 2,2,2‐Trichloroethyl monochloroacetate provides the monoacylation product in a 40% yield with an e.e. of 90%. The dichloroacetate, however, affords the diacylation product exclusively in an enzyme‐independent chemical reaction. With the 2,2,2‐trichloroethyl esters of isobutyric, phenylacetic, and benzoic acid no transesterification could be achieved within 24 hours. The application of vinyl acetate, however, represents a significant improvement in the synthesis of enantiomerically pure monoacetate 3a from meso‐diol 1.