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A Stereoselective Michael-Mannich Annelation Strategy for the Construction of Novel Tetrahydrocarbazoles
- Williams, David R., Bawel, Seth A., Schaugaard, Richard N.
- Organic letters 2017 v.19 no.19 pp. 5098-5101
- alkaloids, chemical reactions, chemical structure, stereoselective synthesis, stereoselectivity
- A novel annelation strategy has been devised for stereoselective synthesis of tetrahydrocarbazoles. The pathway features a regio- and stereocontrolled condensation of indole and its substituted derivatives with electron-deficient 1,3-dienes via a Michael–Mannich reaction sequence. An extension of this method to include cross-conjugated allenes as substrates also results in a Michael–Mannich–Michael cascade, incorporating 2 equiv of indole with increasing product complexity. The formal 4π + 2π cyclization describes a concise route to polycyclic alkaloids of this family.