Formation of spirocyclopentenonyl oxindole frameworks through piancatelli rearrangement Sourav Pramanik, Dr. Jaideep Saha Centre of Biomedical Research, India A new strategy for the access to spirocyclopentenonyl oxindole frameworks will be described. In earlier studies, such scaffolds were targeted via formal [3+2]-annulation/cycloaddition reactions. Previously, our group had reported a Lewis acid catalyzed [3+2]-annulation strategy where spirocyclopropyl oxindoles were employed as a C3 synthon in the form of dipolar donor-acceptor cyclopropane and exo -heterocyclic olefin was used as the partner. 1 Now we present that an assembly of suitably anchored furfuryl alcohol on C3 of an oxindole can render aza-Piancatelli rearrangement and furnish the corresponding spirocyclic aminocyclopentenone frameworks. Catalytic phosphomolybdic acid in 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) was found as the effective promoter for this reaction. 2 This development is expected to push the boundary of unexplored chemical space of spirocyclopentane oxindole-based structures.
References 1. Singh, K.; Pramanik, S.; Hamlin, T. A.; Mondal, B.; Das, D. and Saha, . Chem.Commun., 2019, 55, 7069-7072. 2. Pramanik, S.; Jagadeesh, C.; Chatterjee, A.; Debnath, S. C. and Saha, J. Org. Biomol. Chem., 2022,20,5249-5253.
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© The Author(s), 2022
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