[reaction: see text] The O-directed hydrostannation of various propargyloxy substrates is reported with Ph(3)SnH/Et(3)B.

Asymmetric total syntheses of (+)-azinothricin and (+)-kettapeptin have been completed through a common new pathway that exploits a highly chemoselective coupling reaction between the fully elaborated cyclodepsipeptide 5 and the glycal activated esters 3 and 4 at the final stages of both respective syntheses.

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The synthesis of three potent new antitumor agents is described: the A83586C-citropeptin hybrid (1), the A83586C-GE3 hybrid (2), and l-Pro-A83586C (3). Significantly, compounds 1 and 2 function as highly potent inhibitors of beta-catenin/TCF4 signaling within cancer cells, while simultaneously downregulating osteopontin (Opn) expression. A83586C antitumor cyclodepsipeptides also inhibit E2F-mediated transcription by downregulating E2F1 expression and inducing dephosphorylation of the oncogenic hyperphosphorylated retinoblastoma protein (pRb).

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