Díaz-Salazar H, Rodríguez-Colín JC, Vazquez-Chavez J, Hernández-Rodríguez M. The Chameleonic Nature of the Nitro Group Applied to a Base-Promoted Cascade Reaction To Afford Indane-Fused Dihydrofurans.
J Org Chem 2023;
88:8150-8162. [PMID:
37341114 DOI:
10.1021/acs.joc.3c00132]
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Abstract
We disclose a Michael/Conia-ene/SN2 cascade reaction for the synthesis of Indane-fused dihydrofurans from 1,3-dicarbonyl compounds and 2-alkynylnitrostyrenes promoted by potassium carbonate in DMSO at room temperature. In this reaction, the nitro group has a chameleonic role, first as an electron-withdrawing group for the Michael addition, then the nitronate behaves as a nucleophile, and finally, the allylic nitro acts as a leaving group. The product is obtained as a single diastereomer, affording up to 82% with 1,3-keto esters and 58% with 1,3-diketones. Furthermore, DFT calculations of the reaction mechanism explained the chemoselective addition of the nitronate over the enolate to the unactivated triple bond, with the enolate addition being highly endothermic.
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