Constructing fused N-heterocycles from unprotected mesoionic N-heterocyclic olefins and organic azides via diazo transfer

Abstract

Mesoionic N-heterocyclic olefins (mNHOs) were first reported last year and their reactivity remains largely unexplored. Herein we report the reaction of unprotected mNHOs and organic azides as a novel synthetic...

N2/CO Exchange at a Vinylidene Carbon Center: Stable Alkylidene Ketenes and Alkylidene Thioketenes from 1,2,3-Triazole Derived Diazoalkenes

“…In analogy to the recently described synthesis of imidazole-based diazoalkenes, the mechanism most likely involves initial attack of the strong carbon donor onto the terminal N atom of nitrous oxide ( I ), followed by proton migration to II and dehydration (Scheme ). , …”

“…In analogy to the recently described synthesis of imidazole-based diazoalkenes, the mechanism most likely involves initial attack of the strong carbon donor onto the terminal N atom of nitrous oxide (I), followed by proton migration to II and dehydration (Scheme 2). 40,41 The transfer of N 2 from N 2 O to form diazo species is typically a challenging process, 42 with few literature precedents. 43,44 Note, the analogy between the imidazole mNHO 39 and the 1,2,3-triazole mNHO-based reactions is not obvious, considering that the reaction of normal N-heterocyclic olefins (NHOs) with N 2 O gives dimeric species of the type R 2 C CH(NN)HCCR 2 and not the crucial diazoalkenes.…”

Nitrene formation is the first step of the thermal and photochemical decomposition reactions of organic azides

“…For example, they are important components in click chemistry 1–3 or synthesis of energetic materials. 4–12 Most of these applications as well as their exceptional reactivity arise from their ability to generate nitrene intermediates after N 2 extrusion. 13–17 Although organic azides are known for more than a century, 18 the decomposition reaction mechanism at an atomistic level is still under discussion.…”

Catalytic Isomerization of Unprotected Mesoionic N‐Heterocyclic Olefins and Their Lewis Adducts

“…[6] More recently, the novel C 5 -unprotected mNHO (Scheme 1) was also synthesized via the deprotonation of a 1,2,3-triazolium salt bearing a benzyl group at the C 4 -position, and it showed interesting reactivity towards CO 2 , D 2 O and various Lewis acids, [7] dioxygen, [8] and organic azides. [9] It is highly desirable to gain mechanistic insight into the potential tautomerization between the mNHO and the MIC forms of such unprotected mNHOs as well as their interesting reactivity towards various Lewis acids in solution. In contrast, many NHC-catalyzed reactions have been well understood by recent DFT studies.…”

“…Recently, C 5 ‐substituted mNHOs were reported to be useful ligands in rhodium and boron complexes [5] as well as organocatalysts in hydroboration reactions [6] . More recently, the novel C 5 ‐unprotected mNHO (Scheme 1) was also synthesized via the deprotonation of a 1,2,3‐triazolium salt bearing a benzyl group at the C 4 ‐position, and it showed interesting reactivity towards CO 2 , D 2 O and various Lewis acids, [7] dioxygen, [8] and organic azides [9] . It is highly desirable to gain mechanistic insight into the potential tautomerization between the mNHO and the MIC forms of such unprotected mNHOs as well as their interesting reactivity towards various Lewis acids in solution.…”