Chemical versatility of azide radical: journey from a transient species to synthetic accessibility in organic transformations

Abstract

This review describes the characteristic features of simple and nascent N-centered azide radical, and its unique reactivity in fine chemical synthesis with detailed mechanistic discussions.

Rhodium-catalyzed coupling-cyclization ofo-alkynyl/propargyl arylazides oro-azidoaryl acetylenic ketones with arylisocyanides: synthesis of 6H-indolo[2,3-b]quinolines, dibenzonaphthyridones and dihydrodibenzo[b,g] [1,8]-naphthyridines

“…On the basis of the above experimental results and relevant literature precedents, 8–10,14 a possible mechanism for the formation of 3 , 5 and 7 is proposed in Scheme 3 (with the formation of 3 as an example). Initially, arylisocyanide 2 coordinates with [Rh(COD)Cl] 2 to give intermediate A , which coordinates with o -alkynyl arylazides 1 to generate B .…”

“…Isocyanides 8 and organic azides 9 have proven to be versatile synthetic intermediates for the synthesis of diverse nitrogen-containing heterocyclic systems. In this text, transition-metal-catalyzed reactions of organic azides with isocyanides have emerged as powerful tools for the construction of N-containing compounds employing carbodiimides generated by the coupling reaction of organic azides with isocyanides as a key intermediate.…”

Photogenerated Azido Radical Mediated Oxidation: Access to Carbonyl Functionality from Alcohols, Alkylarenes, and Olefins via Organophotoredox

“…Azide radical is a small and interesting all‐nitrogen polyatomic species with high electrophilicity, which shows different reaction pathways like addition, oxidation, and intermolecular H‐atom transfer (HAT) under certain circumstances [13] . Recently, we have described the chemical versatility of azide radical in the organic synthesis as a transient N‐centered radical in a review [13a] . Importantly, the unique ability of N 3 ⋅ to serve as a potent H‐atom abstractor is thought for utilization in various C−H functionalization reactions primarily by oxidation or trapping of these relayed radicals in novel ways [14] .…”

“…Importantly, the unique ability of N 3 ⋅ to serve as a potent H‐atom abstractor is thought for utilization in various C−H functionalization reactions primarily by oxidation or trapping of these relayed radicals in novel ways [14] . Very recently, mild protocols have been developed for the catalytic generation of N 3 • to explore its selective HAT ability for organic transformations [13a,14,15] . The essential factors to govern the selective C−H abstraction are the radical polarity (electronically matched) and larger BDE of H−N 3 (ca.…”

Cu-Electrocatalytic Diazidation of Alkenes at ppm Catalyst Loading

“…The 1,2-diamine moiety is featured in numerous natural products, pharmaceutical compounds, and molecular catalysts. − While numerous efforts have been devoted to the development of efficient and practical alkene diamination methods, it remains challenging to directly install two amino groups across the alkene system to provide 1,2-diamines, especially free primary 1,2-diamines. ,, Alkene 1,2-diazidation reactions provide an attractive alternative strategy for 1,2-diamine synthesis because the vicinal diazide can be easily reduced to free primary 1,2-diamines. Significant progress has been achieved over the past decade in alkene 1,2-diazidation reactions, , mainly through Pd-, Fe-, − and Cu-catalyzed − radical azidation (Figure A, top). Unfortunately, these methods still suffer from drawbacks such as the use of relatively high metal catalyst loading (1–10 mol %) and stoichiometric amounts of chemical oxidants (e.g., iodine­(III) reagents ,,, and organic peroxides ,, ) and limited compatibility of electron-deficient alkenes.…”