Syntheses of 5a‘-<i>h</i><i>omo</i>-Vinblastine and Congeners Designed to Establish Structural Determinants for Isolation of Atropisomers
作者:Martin E. Kuehne、Scott D. Cowen、Feng Xu、Linda S. Borman
DOI:10.1021/jo000249z
日期:2001.8.1
The syntheses of 5a'-homo-vinblastine (3a) and its C-20' methyl congener 62a were achieved. In contrast to vinblastine, these compounds did not allow isolation of atropisomers because of their lower conformational inversion barrier. However, annelation of a six-membered ring to the conformationally mobile D'-piperidine ring provided an isolated atropisomer 81a, which could be converted to its lower energy conformation 65a on heating. The 5a'-homo-vinblastine congeners 3a, 62a, and 65a showed vinblastine-like inhibition of tubulin polymerization and cytotoxicity to L1210 leukemia cells, albeit at lower potency for the latter activity, than that found with the corresponding compounds in the vinblastine series.