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Abstract The direct Friedel–Crafts‐type coupling and dedinitrogenation reactions of vinyldiazo compounds with aromatic compounds using a metal‐free strategy are described. This Brønsted acid catalyzed method is efficient for the formation of α‐diazo β‐carbocations (vinyldiazonium ions), vinyl carbocations, and allylic or homoallylic carbocation species via vinyldiazo compounds. By choosing suitable nucleophilic reagents to selectively capture these intermediates, both trisubstituted α,β‐unsaturated esters, β‐indole‐substituted diazo esters, and dienes are obtained with good to high yields and selectivity. Experimental insights implicate a reaction mechanism involving the selective protonation of vinyldiazo compounds and the subsequent release of dinitrogen to form vinyl cations that undergo intramolecular 1,3‐ and 1,4‐ hydride transfer processes as well as fragmentation.
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Functionalized vinyldiazo compounds: New players in asymmetric catalysis
The catalytic uses of metal carbenes for addition, insertion, and cycloaddition reactions are dependent on their carbene precursor. The limited methods available for the preparation of diazo esters, which are the most common carbene precursors, restricts their ability to impart structural diversity in metal carbene reactions. Here we report a new methodology for the preparation of diverse vinyldiazoacetate esters and their effective uses in highly enantiocontrolled cyclopropanation, N-H bond insertion, O-H bond insertion, and [3+2] cycloaddition reactions. 1,2,3-Triazine 1-oxides with a sp3-C-H bond at the 5-position undergo base catalyzed Dimroth-type rearrangement to form multiply substituted oximidovinyldiazoacetates in high yields at or below room temperature, and these diverse vinyldiazo compounds undergo catalytic metal carbene transformations to produce oximidovinylcyclopropanes, α-oximidovinyl-α-amino acids and α-hydroxy acids, as well as tricyclic indole derivatives in high yields and enantioselectivities. The new access to vinyldiazo compounds has applicability to a vast array of metal carbene transformations.
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- Award ID(s):
- 2054845
- PAR ID:
- 10528014
- Publisher / Repository:
- CELL Press
- Date Published:
- Journal Name:
- Chem Catalysis
- Volume:
- 3
- Issue:
- 10
- ISSN:
- 2667-1093
- Page Range / eLocation ID:
- 100770
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1016/j.checat.2023.100770
