Willy Walther

Enzymatic preparation of chiral 3-(hydroxymethyl)piperidine derivatives

Abstract t-Butyl (R)-3-(hydroxymethyl)-1-piperidinecarboxylate was prepared with lipase P in up to 98 % ee by means of enantioselective esterification of the racemic alcohol as well as by enantioselective hydrolysis of the corresponding butyryl ester and subsequent chemical hydrolysis of the retained (R)-ester. A work-up procedure feasible on the kg-scale is described.

Die Massenspektren der Pyrrolidide einiger aliphatisch-alicyclischer Carbonsäuren

The mass spectra of the pyrrolidides of some long-chain carboxylic acids with alicyclic residues attached to their ω-end are discussed and compared with the spectra of the corresponding esters. Fragmentation triggered by the pyrrolidide group generates a series of peaks, which clearly exhibits the size and the structure of the carbon chain.

ENZYMATIC PREPARATION OF (R)-3- HYDROXY-2-METHYLPROPYL BUTYRATE BY ASYMMETRIC HYDROLYSIS

(R)-3-Hydroxy-2-methylpropyl butyrate was formed by asymmetric hydrolysis of the corresponding prochiral diester with lipase P (Amano) in high enantiomeric excess. Various physical and chemical reaction parameters were altered in order to optimize the stereoselectivity of the enzymatic reaction; low temperature (0d`C) combined with the application of salting-in salts or (polyhydric) alcohols turned out to be the most suitable systems providing the monobutyrate in 96% ee. Attempts towards chiral monobutyrate by enzymatic esterification of the corresponding prochiral diol were unsuccessful.