Several C-13 amidopaclitaxel analogs have been synthesized during the course of our structure-activity relationship study at the C-13 position. These include 4-deacetyl-13-amidopaclitaxel (4), 13-amidopaclitaxel 4-(methyl carbonate) derivatives (5a,b), and 13-amidopaclitaxel (6). None of these novel C-13 amidopaclitaxel analogs retain any activity in the tubulin polymerization assay or the in vitro cytotoxicity assay.