Enantioselective Formal Synthesis of (+)-Cycloclavine and Total Synthesis of (+)-5-epi-Cycloclavine

Starting from the commercially available 4-bromoindole, a concise and efficient enantioselective formal synthesis of (+)-cycloclavine (1) in 13 steps with 2.0% overall yield and a total synthesis of (+)-5-epi-cycloclavine (2) in 14 steps with 3.3% overall yield were achieved. Key features of the syntheses include the addition of a Grignard reagent to the CN/Heck reaction sequence to construct the fused 6–5–6 ring systems, cyclopropanation, an ester aminolysis reaction, and the first example of the construction of a 3-azabicyclo­[3,1,0]­hexane through an intramolecular [3 + 2] cycloaddition/nitrogen extrusion.