Stereoselective Total Synthesis and Structural Elucidation of (-)-Indoxamycins A-F

In this study, a concise and stereoselective approach for the divergent total synthesis of (-)-indoxamycins A-F is described. The key steps of the strategy include an Ireland-Claisen rearrangement, an enantioselective 1,6-enyne reductive cyclization, and a tandem 1,2-addition/oxa-Michael/methylenation reaction. The relative and absolute configuration of these natural products has been unambiguously elucidated, and their cytotoxic activities against HT-29 and A-549 tumor cell lines are also reported.