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Updated: Aug 18, 2025

Protocol for the Synthesis of Ortho-trifluoromethoxylated Aniline Derivatives
Published on: January 19, 2016
Asymmetric synthesis of the perhydroepoxyethanoindole core via sequential [4 + 2]-addition/reduction/fluoroannulation
Madavi S Prasad1, Murugesan Sivaprakash1
1Asymmetric synthesis and catalysis laboratory, Department of Chemistry, Central University of Tamil Nadu (CUTN), Tiruvarur-610 005, India. shivaprasad@cutn.ac.in.
Abstract:
Herein, we present the sequential aminocatalytic [4 + 2]-addition/reduction and fluoroannulation reactions to afford a novel class of bridged fluoro-perhydroepoxyethanoindole spiropyrazolone and fluoro-perhydroepoxyethanoindole spirooxindole moieties with six contiguous stereocenters. An array of perhydroepoxyethanoindole core derivatives (up to 31 examples) mimicking aspidosperma alkaloids were obtained with moderate to good yields and excellent enantio- and diastereo-selectivities (up to 69% overall yield, up to 99.9% ee and up to >20 : 1 dr). Furthermore, we have also disclosed the synthesis of the unexpected tribromo derivative of hexahydroepoxyethanoindole spiropyrazolone in a moderate yield with excellent selectivity by employing the developed protocol in sequential bromoannulation reactions.
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