Synthesis of 7β-Sulfur Analogues of Paclitaxel Utilizing a Novel Epimerization of the 7α-Thiol Group
作者:Harold Mastalerz、Guifen Zhang、John Kadow、Craig Fairchild、Byron Long、Dolatrai M. Vyas
DOI:10.1021/ol015727m
日期:2001.5.1
[GRAPHICS]90 degreesCPaclitaxel analogues with a sulfur group at the 7 beta position were required for SAR studies, Attempts to generate these compounds by displacing a 7 alpha leaving group with sulfur nucleophiles were unsuccessful. Instead, these compounds were successfully prepared from a 7 beta -thiol intermediate that was obtained by a base-catalyzed epimerization of the 7 alpha -thiol derivative. The epimerization presumably proceeds through a thioaldehyde intermediate and exhibits the opposite stereochemical preference of its oxygen counterpart.