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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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BIMP‐Catalyzed 1,3‐Prototropic Shift for the Highly Enantioselective Synthesis of Conjugated Cyclohexenones
Abstract A bifunctional iminophosphorane (BIMP)‐catalysed enantioselective synthesis of α,β‐unsaturated cyclohexenones through a facially selective 1,3‐prototropic shift of β,γ‐unsaturated prochiral isomers, under mild reaction conditions and in short reaction times, on a range of structurally diverse substrates, is reported. α,β‐Unsaturated cyclohexenone products primed for downstream derivatisation were obtained in high yields (up to 99 %) and consistently high enantioselectivity (up to 99 %ee). Computational studies into the reaction mechanism and origins of enantioselectivity, including multivariate linear regression of TS energy, were carried out and the obtained data were found to be in good agreement with experimental findings.
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- Award ID(s):
- 1955876
- PAR ID:
- 10202041
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Angewandte Chemie
- Volume:
- 132
- Issue:
- 40
- ISSN:
- 0044-8249
- Page Range / eLocation ID:
- p. 17570-17575
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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