An Fe/Cu-mediated one-pot ketone synthesis was reported; Unlike Ni- and Pd-mediated one-pot ketone syntheses, the reported Fe/Cu-mediated method allowed selective activation and coupling of alkyl iodides over vinyl iodides. The newly developed one-pot ketone synthesis was applied to a synthesis of vinyl iodide/ketone 13, the left half of halichondrin B, as well as vinyl iodide/ketone 8a, the C20-C26 building block of halichondrins.