Balanna, K and Barik, S and Shee, S and Gonnade, RG and Biju, AT (2022) Dynamic kinetic resolution of γ,γ-disubstituted indole 2-carboxaldehydes via NHC-Lewis acid cooperative catalysis for the synthesis of tetracyclic ϵ-lactones. In: Chemical Science .
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Abstract
The ubiquity of ϵ-lactones in various biologically active compounds inspired the development of efficient and enantioselective routes to these target compounds. Described herein is the enantioselective synthesis of indole-fused ϵ-lactones by the N-heterocyclic carbene (NHC)-Lewis acid cooperative catalyzed dynamic kinetic resolution (DKR) of in situ generated γ,γ-disubstituted indole 2-carboxaldehydes. The Bi(OTf)3-catalyzed Friedel-Crafts reaction of indole-2-carboxaldehyde with 2-hydroxy phenyl p-quinone methides generates γ,γ-disubstituted indole 2-carboxaldehydes, which in the presence of NHC and Bi(OTf)3 afforded the desired tetracyclic ϵ-lactones in up to 93 yield and >99 : 1 er. Moreover, preliminary studies on the mechanism of this formal 4 + 3 annulation are also provided.
| Item Type: | Journal Article |
|---|---|
| Publication: | Chemical Science |
| Publisher: | Royal Society of Chemistry |
| Additional Information: | The copyright for this article belongs to the Author(s). |
| Keywords: | Bioactivity; Catalysis; Enantioselectivity; Esters; Friedel-Crafts reaction; Polycyclic aromatic hydrocarbons; Quinone, Biologically active compounds; Cooperative catalysis; Dynamic kinetic resolution; Enantioselective; Enantioselective synthesis; Friedel-Craft reactions; Lewis Acid; N-heterocyclic carbenes; p-Quinone methides; Target compound, Synthesis (chemical) |
| Department/Centre: | Division of Chemical Sciences > Organic Chemistry |
| Date Deposited: | 10 Nov 2022 06:19 |
| Last Modified: | 10 Nov 2022 06:19 |
| URI: | https://eprints.iisc.ac.in/id/eprint/77855 |
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