Recent Advances in Denitrogenative Reactions of Pyridotriazoles

Diazo compounds display versatile reactivity and therefore are widely used in organic synthesis. Diazo compounds bearing a 2-pyridyl or a related azine moiety on the diazo carbon exist in the form of fused 1,2,3-triazoles. In this short review, we summarize the recent advances in denitrogenative reactions of [1,2,3]triazolo[1,5-a]pyridines (‘pyridotriazoles’) and related fused 1,2,3-triazoles. Over the past decade, there has been a surge of activity in this field, with novel denitrogenative reactions of pyridotriazoles induced by metal compounds, light, and Brønsted and Lewis acids having been devised. As a result, heterocyclic compounds and functionalized α-picolines as well as bio­active molecules have been synthesized. In the review, emphasis is also placed on the mechanisms of the new reactions.1 Introduction2 Ring-Chain Isomerization of Pyridotriazoles3 Metal-Catalyzed Reactions3.1 Rh(II) Catalysis3.2 Rh(III) Catalysis3.3 Cu Catalysis3.4 Pd Catalysis3.5 Catalysis by Other Metals4 Metal-Free Reactions5 Conclusion

Highly branched unsaturated polyethylenes achievable using strained imino-cyclopenta[b]pyridyl-nickel precatalysts

Highly branched and unsaturated PEs with narrow PDIs have been obtained using nickel catalysts that display high activities, rapid regeneration of active species and high rates of chain isomerization.

Constraining the Conformational Landscape of a Polyether Building Block by Raman Jet Spectroscopy

Collisionally induced chain isomerization of CH

Synthesis and crystal structures of two novel triazolopyridine compounds solved by local L.S. minimizations from powder diffraction data

The heteroaryl-substituted triazolopyridines 3-phenyl-7-(pyrazin-2-yl)-[1,2,3]triazolo[1,5-a]pyridine (2) and 3-[6-(pyridazin-3-yl)-pyridin-2-yl]-[1,2,3]triazolo[1,5-a]pyridine (4) have been synthesized and characterized (by HRMS, IR, 1H and 13C NMR, XRPD, melting point). The crystal structures have been solved from laboratory powder X-ray diffraction data with the direct-space strategy TALP for molecular compounds based on fast local least-squares minimizations. The crystal structure confirmed the formation of the tridentate compound 4 from a ring chain isomerization process. The almost planar arrangement of atoms in both the structures favors the presence of intermolecular π–π interactions, although weak C–H···N electrostatic interactions seem to be also important for the stabilization of the structure. Powder diffraction data have also proved to be sensible enough to determine the relative rotations of the six-membered rings despite the weak difference in scattering power between C and N atoms.