Browsing by Subject "Isocyanide"

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    Heterocyclizations at the Isocyanide Carbon: Mechanistic Insights into the 2-Isocyanoaniline to Benzimidazole Conversion
    (American Chemical Society, 2026-01-15) Alajarín Cerón, Mateo; Marín Luna, Marta; Química Orgánica
    Benzo-fused heteroazacycles can form through spontaneous cyclizations of phenylisocyanides bearing some electron donor substituents at the ortho position. Although such reactions have been known since the 1970s, a clear mechanistic understanding of these transformations remains absent. Here, we disclose a detailed computational analysis aimed at elucidating the more plausible mechanism for one of these cyclizations, the o-isocyanoaniline to benzimidazole conversion. Our results show that a transient 1,4-diazabutatriene could play a key role in this cyclization by enabling a reaction pathway of lower barrier than the unimolecular concerted process.
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    Intramolecular cyclization of Azido-Isocyanides triggered by the Azide Anion: an experimental and computational study
    (American Chemical Society Publications, 2023-06-20) Alajarín Cerón, Mateo; Cutillas Font, Guillermo; López Leonardo, Carmen; Orenes, Raul-Angel; Marín Luna, Marta; Pastor Vivero, Aurelia; Química Orgánica
    This work describes the unprecedented intramolecular cyclization occurring in a set of alfa-azido-beta-isocyanides in the presence of catalytic amounts of sodium azide. These species yield the tricyclic cyanamides [1,2,3]triazolo[1,5-a]quinoxaline-5(4H)-carbonitriles, whereas in the presence of an excess of the same reagent, the azido-isocyanides convert into the respective C-substituted tetrazoles through a [3+2] cycloaddition between the cyano group of the intermediate cyanamides and the azide anion. The formation of tricyclic cyanamides has been examined by experimental and computational means. The computational study discloses the intermediacy of a long-lived N-cyanoamide anion, detected by NMR monitoring of the experiments, subsequently converting into the final cyanamide in the rate determining step. The chemical behavior of these azido-isocyanides endowed with an aryl-triazolyl linker, has been compared with that of a structurally identical azido-cyanide isomer, experiencing a conventional intramolecular [3+2] cycloaddition between its azido and cyanide functionalities. The synthetic procedures described herein constitute metal-free approaches to novel complex heterocyclic systems, such as [1,2,3]triazolo[1,5-a]quinoxalines and 9H-benzo[f]tetrazolo[1,5-d][1,2,3]triazolo[1,5-a][1,4]diazepines.