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Updated: May 21, 2026

Efficient Construction of Drug-like Bispirocyclic Scaffolds Via Organocatalytic Cycloadditions of α-Imino γ-Lactones and Alkylidene Pyrazolones
Published on: February 7, 2019
Scalable Synthesis of Seven-Membered 3,4-Fused Tricyclic Indole Scaffolds Enabling Conformationally Fixed
Olga I Adaeva1, Dmitry V Demchuk1, Marina N Semenova1
1N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 119991 Moscow, Russian Federation.
Abstract:
We report an improved and scalable synthetic route to seven-membered 3,4-fused tricyclic indole scaffolds, providing practical access to the target framework with good overall efficiency and reproducibility. A key feature is Sc(OTf)3-promoted regioselective Fischer indolization of ortho-substituted phenylhydrazone 5b, which overrides the anomalous pathway observed under conventional acidic conditions. The synthetic utility of the scaffold was demonstrated through the preparation of aminobenzosuberene-inspired derivatives. Preliminary biological evaluation revealed that compound 1b exhibited antimitotic activity at 0.2 μM.
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