Balanna, Kuruva ; Barik, Soumen ; Shee, Sayan ; Gonnade, Rajesh G. ; Biju, Akkattu T. (2022) Dynamic kinetic resolution of γ,γ-disubstituted indole 2-carboxaldehydes via NHC-Lewis acid cooperative catalysis for the synthesis of tetracyclic ε-lactones Chemical Science, 13 (39). pp. 11513-11518. ISSN 2041-6520
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Official URL: http://doi.org/10.1039/D2SC03745A
Related URL: http://dx.doi.org/10.1039/D2SC03745A
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: | Article |
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Source: | Copyright of this article belongs to Royal Society of Chemistry |
ID Code: | 128573 |
Deposited On: | 03 Nov 2022 05:59 |
Last Modified: | 03 Nov 2022 05:59 |
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