12-Aza-epothilones ('Azathilones') 1 and 2 have been prepared through ring-closing olefin metathesis or macrolactonization-based cyclization reactions. While RCM of the respective dienes 9 and 12 was found to be very effective and produced macrocyclic olefins
with high E selectivity, the subsequent reduction of the 9,10-double bond proved to be unexpectedly difficult and low-yielding. Preparation of azathilone 2 was also accomplished via macrolactonization and this approach was found to be more effective. Compound 2
is a highly potent inhibitor of human cancer cell growth in vitro. The activity of this analog is comparable with that of Epo A, both in terms of cytotoxicity against drug-sensitive human cancer cells as well as its tubulin-polymerizing activity. However, in contrast to Epo A, 2
is considerably less potent against multidrug-resistant cancer cells.
12-Aza-epothilones(“Azathilones”)1和2通过环内烯烃交换或基于大环内酯化反应的环化反应制备。虽然分别使用双烯烃9和12的RCM非常有效,并产生高E选择性的大环烯烃,但随后的9,10-双键还原被证明出乎意料地困难和低产率。通过大环内酯化也成功制备了azathilone 2,这种方法被发现更有效。化合物2是体外人类癌细胞生长的高效抑制剂。这种类似物的活性与Epo A相当,无论是对于药物敏感的人类癌细胞的细胞毒性还是其微管聚合活性。然而,与Epo A相比,2对多药耐药癌细胞的作用显著较弱。