Synthesis of Enantiomerically Purecis- andtrans-4-Amino-1-oxyl-2,2,6,6-tetramethylpiperidine-3-carboxylic Acid: A Spin-Labelled, Cyclic, Chiral β-Amino Acid, and 3D-Structural Analysis of a Doubly Spin-Labelled β-Hexapeptide
作者:Karen Wright、Matthieu Sarciaux、Augustin de Castries、Michel Wakselman、Jean-Paul Mazaleyrat、Antonio Toffoletti、Carlo Corvaja、Marco Crisma、Cristina Peggion、Fernando Formaggio、Claudio Toniolo
DOI:10.1002/ejoc.200700153
日期:2007.7
established by X-ray diffraction analysis of one of them, combined with 1H NMR spectroscopic studies after nitroxide reduction. Removal of the chiral auxiliary from the separated diastereomers of 3 by hydrogenation and regeneration of the nitroxide radical gave expected amino esters 4. A model β-hexapeptide containing (3R,4S)-β-TOAC combined with (1S,2S)-2-aminocyclohexane carboxylic acid was synthesised
3-羧甲基-1-氧基-2,2,6,6-四甲基-4-哌啶酮 (1) 与 (R)- 或 (S)-α-甲基苄胺的胺化得到相应的烯胺 2。而用 NaBH3CN 还原/CH3COOH 主要提供 3, (1'R,3S,4S)/(1'R,3R,4R) 或 (1'S,3R,4R)/(1'S,3S) 的两种可能的顺式非对映异构体的混合物,4S),可通过其 HCl 盐的结晶进行分离,使用 NaBH4/(CH3)2CHCOOH 作为还原剂产生 3 (1'R,3S,4R) 的一种反式和一种顺式非对映异构体的混合物)/(1'R,3R,4R) 或 (1'S,3R,4S)/(1'S,3S,4S) 的比例取决于所使用的条件。3 的四种非对映异构体的立体化学通过其中一种的 X 射线衍射分析明确确定,并结合硝基氧还原后的 1 H NMR 光谱研究。