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

Autor: Rajendra M. Srivastava, Wagner M. Faustino, Gene B. Carpenter, Maria José da Silva, João R. de Freitas Filho, Suzana C. de Melo Souto
Rok vydání: 2004
Předmět:
Zdroj: Tetrahedron. 60:10761-10769
ISSN: 0040-4020
DOI: 10.1016/j.tet.2004.08.075
Popis: For synthesizing title compounds, first we carried out the Ferrier's rearrangement involving tri-O-acetyl- d -glucal 1 and alcohols 2a–e using Montmorillonite K-10 as a catalyst. This reaction gave diastereoisomeric mixture of 3a–e and 4a–e . Basic hydrolysis of each pair of diastereoisomeric mixture furnished title compounds 5a–e and 6a–e , which were separated very carefully over a silica gel column 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 results with the crystallographic data. We have also determined the rotational barrier of C(8) and O(9) bond in both (R) and (S) enantiomers of compounds 5a and 6a .
Databáze: OpenAIRE
Externí odkaz: