An unprecedented route to achieve persistent 1H-azirine

Abstract

1H-azirine, a highly reactive, antiaromatic, and unstable tautomer of the aromatic, stable, and (sometimes) isolable 2H-azirine, is stabilized, both thermodynamically and kinetically, via an unprecedented route, where the latter serves...

3-Fluoro-2H-azirine: Generation, Characterization, and Photochemistry

“…Three-membered organic heterocycles are versatile building blocks that have attracted considerable interest in synthetic and biological chemistry. − 2 H -Azirine, the simplest unsaturated heterocycle consisting of a nitrogen atom, has been the target of numerous experimental and theoretical studies since its first synthesis in 1932 by Neber. − These intensive studies mostly originate from the high strain of the three-membered azirine ring in combination with sufficient stability for chemical modification, rendering 2 H -azirines widely applicable in the synthesis of functionalized amino compounds, heterocycles, and substituted allenes and aziridines. − In addition to their use as versatile synthetic blocks, 2 H -azirines are recognized as biologically active compounds. Recently, a novel reactive 2 H -azirine-based probe has been designed and utilized in the chemoselective modification of carboxyl groups in proteins under both in vitro and in situ conditions with excellent efficiency. , Medicinally, the azirine unit can also be found in natural antibiotics including ( R )-(−)- and ( S )-(+)-dysidazirine. , …”

“…Recently, the structure, spectroscopic data, and formation mechanism of 3-hydroxyl-2 H -azirine have been comprehensively explored by using quantum chemical calculations, and the results suggest that it might be formed through the reaction between 2 H -azirine and an OH radical at the surface of cold interstellar ices . Similarly, the collisional reaction between azirine and the F atom in the ISM could furnish the fluorine-substituted azirine, as F-bearing species have already been identified under astrophysical conditions. − More recently, the molecular structures and stability of 1-fluoro-1 H -azirine ( A ) and 2-fluoro-2 H -azirine have ( B ) been theoretically studied . To the contrary, the isomeric 3-fluoro-2 H -azirine ( C ) remains barely studied (Scheme ), whereas the nitrile isomer CH 2 FCN is a stable compound that has been well characterized …”

“…41−43 More recently, the molecular structures and stability of 1-fluoro-1H-azirine (A) and 2-fluoro-2H-azirine have (B) been theoretically studied. 13 To the contrary, the isomeric 3-fluoro-2H-azirine (C) remains barely studied (Scheme 1), whereas the nitrile isomer CH 2 FCN is a stable compound that has been well characterized. 44 In this article, we report the first generation of 3-fluoro-2Hazirine (cyclic NCH 2 CF, i) through the stepwise decomposition of the acryloyl azide precursor CH 2 CFC(O)N 3 (a, Scheme 2).…”