Antineoplastic agents. 578. Synthesis of stilstatins 1 and 2 and their water-soluble prodrugs.

Efficient syntheses of 3,4-methylenedioxy-4′,5-dimethoxy-2′,3′-dihydroxy-Z-stilbene (stilstatin 1, 2), 3,4,4′-trimethoxy-2′,3′,5-trihydroxy-Z-stilbene (stilstatin 2, 5), and respective phosphate prodrugs have been summarized. Both 2 and 5 were accessed via a convergent step synthesis using phosphonium bromides 6 and 21 in Wittig reactions with 2,3-bis(tert-butyldimethylsilyloxy)-4′-methoxybenzaldehyde 14. Deprotection of silyl ethers 15 and 26 with TBAF furnished 2 and 5, respectively. Phosphorylation of 2 and 5 afforded the phosphoric acid intermediates 17 and 28 for prodrug development. These phosphoric acid precursors were employed in parallel series of reactions to produce a selection of metal cation prodrug candidates. The biological activities of stilstatins 1 (2) and 2 (5) and their respective prodrugs were evaluated against a panel of one murine (P388) and six human cancer cell lines. Compared to combretastatin A-2 (1), stilstatin 1 (2) has an additional vicinal hydroxy group on the B ring, the pr...