Brønsted Acid Catalyzed Friedel–Crafts‐Type Coupling and Dedinitrogenation Reactions of Vinyldiazo Compounds. (5th June 2020)

• Record Type: Journal Article
• Authors: Zheng, Haifeng; Dong, Kuiyong; Wherritt, Daniel; Arman, Hadi; Doyle, Michael P.
• Is Part Of: Angewandte Chemie. Volume 132:Number 32(2020)
• Page Start: 13715
• Page End: 13719
• Publication Date: 2020-06-05
• Subjects: Brønsted acids -- dedinitrogenation -- Friedel–Crafts coupling -- organocatalysis -- vinyldiazo compounds; Chemistry -- Periodicals; 540
• DOI: 10.1002/ange.202004328
• Languages: English
• ISSNs: 0044-8249

Abstract

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. Abstract : Brønsted acid catalysis provides direct Friedel–Crafts‐type coupling and dedinitrogenation reactions of vinyldiazo compounds, where vinyldiazo compounds serve as the precursor of vinyldiazonium ions, vinyl, and highly reactive allylic and homoallylic carbocation species. By choosing suitable nucleophilic reagents, trisubstituted α, β‐unsaturated esters, β‐indole‐substituted diazo esters, and dienes are obtained with good yields and selectivity.