An Efficient Synthesis of (±)-Dehalo­perophoramidine

Perophoramidine and communesin F are structurally related indole alkaloids with an intriguing polycyclic core containing vicinal all-carbon quaternary stereocenters. Dehalopero­phoramidine is a dehalogenated synthetic analogue of perophoramidine. Synthetic studies toward the total synthesis of dehalopero­phoramidine have led to the discovery of two novel domino processes, the first encompassing four steps and resulting in the formation of an ortho-amide. A thorough study of the reactivity of the ortho-amide functionality revealed the second domino reaction and ultimately yielded the target molecule. The vicinal all-carbon quaternary stereocenters having trans relative stereochemistry are constructed early in the reaction sequence by employing Overman’s samarium mediated reductive dialkylation procedure. Described are the synthetic studies that led to the final eight-step synthesis of dehalopero­phoramidine.