Method for the preparation of N-substituted 4-ketoproline derivatives
AssigneeDegussa AG
InventorsKarlheinz Drauz, Matthias Kottenhahn, Klaus Stingl
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Abstract
Method for the preparation of N-protected 4-ketoproline derivatives of formula I ##STR1## by oxidation of the corresponding N-protected 4-hydroxyproline derivatives of ##STR2## using the system TEMPO (2,2,6,6-tetramethylpiperidinyl oxy free radical)/NaOCl.
Claims8
A process for the preparation of N-substituted 4-ketoproline derivatives of the general formula I ##STR8## by oxidation of the corresponding N-substituted 4-hydroxyproline derivatives of the general formula III ##STR9## wherein R.sup.1 is (C.sub.1 -C.sub.6) alkyl, CO-R.sup.3 or fluorenylmethoxycarbonyl,
- R.sup.2 is NH.sub.2, OR.sup.4,
- R.sup.3 is (H), (C.sub.1 -C.sub.6) aikyl, phenyl, benzyl, benzyloxy, NH.sub.2, NO2-phenyloxy, NO.sub.2 -benzyloxy, (C.sub.1 -C.sub.6) alkoxy or phenyloxy,
- and R.sup.4 is (C.sub.1 -C.sub.6) alkyl, benzyl, phenyl, NO.sub.2 -benzyl, NO.sub.2 -phenyl or alkyl,
- wherein the reaction is carried out in the presence of 2,2,6,6-tetramethylpiperidinyl oxy free radical (TEMPO) and a hypohalide solution.
An (2S)-N-benzyloxycarbonyl-4-oxoproline Isopropyl ester or an (25)-N-benzyloxycarbonyl-4-oxoproline n-butyl ester, which is produced by oxidation of the corresponding N-substituted 4-hydroxyproline derivative compound of the general formula III ##STR10## wherein R.sup.1 is (C.sub.1 -C.sub.6) alkyl CO--R.sup.3 or fluorenylmethoxycarbonyl,
- R.sup.2 is NH.sub.2, OR.sup.4,
- R.sup.3 is (H), (C.sub.1 -C.sub.6) alkyl, phenyl, benzyl, benzyloxy, NH.sub.2, NO2-phenyloxy, NO.sub.2 -benzyloxy, (C.sub.1 -C.sub.6) alkoxy or phenyloxy,
- and R.sup.4 is (C.sub.1 -C.sub.6) alkyl, benzyl, phenyl, NO.sub.2 -benzyl, NO.sub.2 -phenyl or alkyl,
- wherein the reaction is carried out in the presence of 2,2,6,6-tetramethylpiperidinyl oxy free radical (TEMPO) and a hypohalide solution.
Dependencies are inferred from the claim text.