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Construction of Seven-Membered Oxacycles Using a Rh(I)-Catalyzed Cascade C–C Formation/Cleavage of Cyclobutenol Derivatives
- Source :
- The Journal of Organic Chemistry; April 2024, Vol. 89 Issue: 7 p4647-4656, 10p
- Publication Year :
- 2024
-
Abstract
- Herein, we describe the synthesis of substituted oxepane derivatives through the skeletal remodeling of 4-hydroxy-2-cyclobutenones, which are readily prepared from commercially available dialkyl squarates upon their reaction with acrylonitrile. Mechanistically, a Rh(I)-catalyzed C–C bond formation and cleavage cascade is proposed. Specifically, a fused [3.2.0] bicycle is proposed to form from dialkyl squarate-derived cyclobutenols via an unusual Rh(I)-catalyzed intermolecular oxa-Michael addition of a tertiary alcohol with acrylonitrile, followed by an intramolecular conjugate addition/migratory insertion. Subsequent C(sp3)–C(sp3) bond cleavage through a Rh-catalyzed β-carbon elimination is then theorized to furnish the oxepane scaffold. Computational studies support the formation of an intermediate [3.2.0] bicycle but also point to an alternative pathway for the formation of the oxepane products involving a Rh(III) intermediate. Additional studies have shown the overall process to be stereoretentive. The functional groups that are introduced in this process can be leveraged to form fused or bridged ring systems.
Details
- Language :
- English
- ISSN :
- 00223263
- Volume :
- 89
- Issue :
- 7
- Database :
- Supplemental Index
- Journal :
- The Journal of Organic Chemistry
- Publication Type :
- Periodical
- Accession number :
- ejs65788860
- Full Text :
- https://doi.org/10.1021/acs.joc.3c02914