Synthesis, Conformational Properties, and Synthetic Applications of Novel Optically Pure α,α-Disubstituted (<i>R</i>)- and (<i>S</i>)-Glycines (‘α-Chimeras’) Combining Side Chains of Asp, Glu, Leu, Phe, Ser, and Val
作者:Daniel Obrecht、Christine Abrecht、Michael Altorfer、Udo Bohdal、Alfred Grieder、Martina Kleber、Patrick Pfyffer、Klaus Müller
DOI:10.1002/hlca.19960790508
日期:1996.8.7
auxiliary, a novel azlactone/dihydrooxazole interconversion reaction to synthesize optically pure α-substituted (R)- and (S)-serine derivatives coupled with succinimide-ring formation of aspartic-acid derivatives. Based on X-ray structures of (R,S)-9b, (R,S)-11c, (R,S)-18, and (S,S)-30, the absolute configuration of these novel amino-acid building blocks could be unambiguously determined and their preferred
一系列结合Asp,Glu,Leu,Phe,Ser和Val侧链的新型开链和环状构象约束的α,α-二取代(R)-和(S)-甘氨酸衍生物('α-嵌合体')通过外消旋的4-单取代的2-苯基-1,3-恶唑-5(4H)-的5型α-烷基化反应,与(S)-苯丙氨酸环己酰胺(8)反应后拆分得到高效合成辅助,新型的内酯/二氢恶唑互变反应合成光学纯的α-取代的(R)-和(S)-丝氨酸衍生物与天冬氨酸衍生物的琥珀酰亚胺环形成。基于(R,S)-9b,(R,S)-11c,(R,S)-18和(S,S)-30的X射线结构,这些新型氨基酸的绝对构型可以明确地确定嵌段,并评估其在结晶状态下的优选构象。开链衍生物(R,S)-1,(S,S)-3和(R,S)-11c的高度偏爱对于β-转角I型构象,以及琥珀酰亚胺衍生物(R,S)-2,(S,S)-19,(S,S)-24,(S,S,S)-26,和(R,S)-29用于β-转角II型构象以