This paper describes an efficient single step transformation of chiral carnitine and carnitine derivatives into stereoisomerically pure (S)- and (R)-β-substituted-γ-butyrolactones, obtained by intramolecular nucleophilic displacement. (S)- Or (R)-carnitine and (R)-aminocarnitine inner salts give β-hydroxy-γ-butyrolactone and β-amino-γ-butyrolactone respectively (82% and 77%) with the same configuration as the starting material. (R)-Acetylaminocarnitine inner salt gives (R)-β-acetylamino-γ-butyrolactone (90%), while (R)-acetylcarnitine gives 2(5H)-furanone under the same reaction conditions (77%, via cyclization and subsequent elimination reaction). (R)-N-Benzyloxycarnitineamide gives a mixture of pyrrolidinone (11%) and furanoyl imidate (50%) derivatives. The direct transformation of wast (S)-carnitine into the valuable (S)-β-hydroxy-γ-butyrolactone or (after acetylation) into the precious 2(5H)-furanone is of particular interest.
本文介绍了通过分子内亲核置换将手性肉碱和肉碱衍
生物高效地一步转化为立体异构纯(S)-和(R)-δ-取代-δ³
-丁内酯的方法。(S)-或(R)-肉碱和
(R)-氨基肉碱内盐分别得到δ-羟基-δ³
-丁内酯和δ-
氨基-δ³
-丁内酯(82%和 77%),其构型与起始原料相同。(在相同的反应条件下,(R)-乙酰基
氨基肉碱内盐可以得到(R)-δ-乙酰
氨基-δ
-丁内酯(90%),而(R)-
乙酰基肉碱通过环化和随后的消除反应可以得到
2(5H)-呋喃酮(77%)。(R)-N-苄氧基肉碱酰胺可以得到
吡咯烷酮(11%)和
呋喃酰亚胺酯(50%)衍
生物的混合物。废(S)-
卡尼汀直接转化为有价值的(S)-δ-羟基-δ
-丁内酯或(乙酰化后)转化为珍贵的
2(5H)-呋喃酮特别令人感兴趣。