A Stereospecific Route for the Preparation of \u3cem\u3etrans\u3c/em\u3e-Combretastatin Analogs: Synthesis and Cytotoxicity

The stereospecific synthesis of nine trans-combretastatin analogs (5 - 13) is described. The trans geometry of these products was ascertained by the vinylenic proton NMR coupling constants of 15 - 16 Hz, and also by a single crystal x-ray structure of the tetramethoxy compound 6. Continuous 3-day exposure of murine B16 melanoma cells to the trans-combretastatin analogs 5 - 13 showed that two of the analogs (2 and 4) had good cytotoxicity. According to a MTT assay, the IC50 values for compounds 2 and 4 were 4.5 μM and 13.5 μM, respectively. Compounds that exhibited cytotoxic properties contain a 4,4-dimethoxy-transstilbene skeleton