Synthesis, separation and configuration determination of diastereoisomers of (R,S)-1-methyl-3-[3-(aryl)-1,2,4-oxadiazol-5-yl] propyl 2,3-dideoxy-α-d-erythro-hex-2-enopyranosides
作者:Rajendra M. Srivastava、João R. de Freitas Filho、Maria José da Silva、Suzana C. de Melo Souto、Gene B. Carpenter、W.M. Faustino
DOI:10.1016/j.tet.2004.08.075
日期:2004.11
yielding all diastereoisomers in the pure form. One of them 5d was subjected to a single crystal X-ray analysis to determine the correct configuration at the asymmetric carbon atom of the aglycone. The methyl signals of the diastereomers helped to assign the configuration of each diastereoisomer. Molecular orbital calculations of 5d using the semi-empirical method (AM1) has been performed to compare its
为了合成标题化合物,首先我们进行的费里尔的重排涉及三ö乙酰基d-己烯糖1和醇2A - ë使用蒙脱土K-10作为催化剂。该反应得到3a - e和4a - e的非对映异构体混合物。每对非对映异构混合物的碱性水解均提供标题化合物5a – e和6a – e,将其在硅胶柱上非常仔细地分离,得到所有纯净形式的非对映异构体。其中5d对其进行单晶X射线分析,以确定糖苷配基在不对称碳原子上的正确构型。非对映异构体的甲基信号有助于分配每个非对映异构体的构型。已经使用半经验方法(AM1)对5d进行了分子轨道计算,以将其结果与晶体学数据进行比较。我们还确定了化合物5a和6a的(R)和(S)对映异构体中C(8)和O(9)键的旋转势垒。