Grignard addition of 8 to 9 and detosylation afforded amine derivative 19. Pictet-Spengler cyclization of 19 with Eschenmoser's salt and subsequent hydrolysis gave enantiomerically pure (-)-brunsvigine (1). For the total synthesis of (-)-manthine (2), the key intermediate 7 was hydrolyzed to diol 21. Conversion of 21 into 22 followed by regioselective cleavage with DIBAL furnished alcohol 25. Alcohol 25 was
10 μM to explore their cytotoxic activities against a panel of eight cancer cell lines and one non-cancer cell line. Among montanine and its analogues, montanine and its derivatives 12 and 14 showed the highest cytostaticactivity in the initial single-dose screening. However, the native montanine exhibited the greatest antiproliferative activity against cancer cells, with a lower mean IC50 value of
In a search of small molecules active against apoptosis-resistant cancer cells, a skeletal rearrangement of alkaloid haemanthamine was utilized to generate a series of compounds possessing the alkaloid montanine ring system. The synthesized compounds were found to inhibit proliferation of cancer cells resistant to apoptosis at micromolar concentrations. Selected compounds were also active against patient-derived glioblastoma cells expressing stem-cell markers. This is the first report describing the preparation of synthetic analogues of the montanine-type alkaloids with antiproliferative activity. The compounds prepared in the current investigation appear to be a useful starting point for the development of agents to fight cancers with apoptosis resistance, and thus, associated with poor prognoses. (C) 2018 Elsevier Ltd. All rights reserved.
Structures of Montanine, Coccinine, and Manthine<sup>1</sup>
作者:Y. INUBUSHI、H. M. FALES、E. W. WARNHOFF、W. C. WILDMAN