Divergent Total Synthesis of Chaetoglines C to F

The first total syntheses of chaetoglines C–F via a bioinspired and divergent synthetic strategy are reported. Chaetolines C and D were obtained from the condensation of hemiacetal and tryptophan methyl ester building blocks followed by functional group transformations. The synthesis of chaetogline E employed the diastereoselective Pictet–Spengler reaction, and the tetrahydro-carboline skeleton was further utilized as a precursor for an oxidative aromatization reaction to introduce the β-carboline moiety of chaetogline F.