The Chemistry of the [1,2,3]Triazolo[1,5-a]pyridines: An Update

Crystal structure and Hirshfeld surface analysis of 5-oxo-7-phenyl-2-(phenyl-amino)-1H-[1,2,4]triazolo[1,5-a]pyridine-6,8-dicarbo-nitrile dimethyl sulfoxide monosolvate

In the title compound, C₂₀H₁₂N₆O·C₂H₆OS, the [1,2,4]triazolo[1,5-a]pyridine ring system is almost planar and makes dihedral angles of 16.33 (7) and 46.80 (7)°, respectively, with the phenyl-amino and phenyl rings. In the crystal, mol-ecules are linked by inter-molecular N-H⋯O and C-H⋯O hydrogen bonds into chains along the b-axis direction through the dimethyl sulfoxide solvent mol-ecule, forming C(10)R ² ₁(6) motifs. These chains are connected via S-O⋯π inter-actions, π-π stacking inter-actions between the pyridine rings [centroid-to-centroid distance = 3.6662 (9) Å] and van der Waals inter-actions. A Hirshfeld surface analysis of the crystal structure indicates that the most important contributions to the crystal packing are from H⋯H (28.1%), C⋯H/H⋯C (27.2%), N⋯H/H⋯N (19.4%) and O⋯H/H⋯O (9.8%) inter-actions.

Synthesis of 4-(tert-Butyldimethylsilyl)-4,5,6,7-tetrahydro-[1,2,3]triazolo[1,5-a]pyridine

SN2 rection between 4-(tert-butyldimethylsilyl)hex-5-yn-1-yl 4-methylbenzenesulfonate and NaN3 in DMF at 80 °C provided (6-azidohex-1-yn-3-yl)(tert-butyl)dimethylsilane intermediate, which underwent in situ intramolecular thermal Huisgen azide–alkyne cycloaddition reaction. This one-pot process gave 4-(tert-butyldimethylsilyl)-4,5,6,7-tetrahydro-[1,2,3]triazolo[1,5-a]pyridine in 78% yield.

A Predictive Chemistry DFT Study of the N2O Functionalization for the Preparation of Triazolopyridine and Triazoloquinoline Scaffolds

The whole reaction mechanism of the functionalization of N2O for the synthesis of triazolopyridine and triazoloquinoline scaffolds has been unveiled by means of DFT calculations. The rate determining step of...

Nitrous oxide as a diazo transfer reagent: the synthesis of triazolopyridines

Nitrous oxide is a potential diazo transfer reagent, but its applications in organic chemistry are scarce. Here, we show that triazolopyridines and triazoloquinolines are formed in the reactions of metallated 2-alkylpyridines or 2-alkylquinolines with N₂O. The reactions can be performed under mild conditions and give synthetically interesting triazoles in moderate to good yields.

Indium-mediated annulation of 2-azidoaryl aldehydes with propargyl bromides to [1,2,3]triazolo[1,5-a]quinolines

An efficient indium-mediated cascade annulation reaction of 2-azidoaryl aldehydes with propargyl bromides is reported. The aromatic 5/6/6-fused heterocycles, [1,2,3]triazolo[1,5-a]quinoline derivatives, could be constructed in one pot in moderate yields with a broad substrate scope. Mechanistic studies indicated that the reaction proceeded through allenol formation, azide-allene [3 + 2] cycloaddition, and dehydration. The synthetic potential of the products including the denitrogenative functionalization and the Pd-catalyzed coupling reactions has also been explored.

Denitrogenative Transformations of Pyridotriazoles and Related Compounds: Synthesis of N-Containing Heterocyclic Compounds and Beyond

The high demand for new and efficient routes toward synthesis of nitrogen-containing heterocyclic scaffolds has inspired organic chemists to discover several methodologies over recent years. This Perspective highlights one standout approach, which involves the use of pyridotriazoles and related compounds in denitrogenative transformations. Readily available pyridotriazoles undergo ring-chain isomerization to produce uniquely reactive α-diazoimines. Such reactivity, enabled by metal catalysts, additives, or visible-light irradiation, can be applied in transannulation, insertion, cyclopropanation, and many other transformations.

Metal-Free Denitrogenative C-C Couplings of Pyridotriazoles with Boronic Acids To Afford α-Secondary and α-Tertiary Pyridines

Pyridotriazoles are utilized as robust building blocks to access α-secondary and α-tertiary pyridines via the development of a simple yet practically useful metal-free denitrogenative C-C cross-coupling with boronic acids. The reaction shows a high level of functional tolerance, broad substrate scope, and facile scalability. The synthetic potential of the method is demonstrated by the strurctural modification of a bioactive molecule and concise synthesis of pheniramine analogs.

1,2,3-Triazole fused with pyridine/pyrimidine as new template for antimicrobial agents: Regioselective synthesis and identification of potent N-heteroarenes

The 1,2,3-triazole ring fused with pyridine/pyrimidine was explored as new template for the identification of potential antimicrobial agents. The regioselective synthesis of these pre-designed N-heteroarenes was achieved via exploring the application of Buchwald's strategy (i.e. C-N bond formation/reduction/diazotization/cyclization sequence) to the N-heteroarene system. Two of them showed promising antibacterial (comparable to streptomycin) and several showed potent antifungal (comparable to mancozeb) activities.

Cu-Catalyzed Transannulation Reaction of Pyridotriazoles with Terminal Alkynes under Aerobic Conditions: Efficient Synthesis of Indolizines

The Cu(I)-catalyzed denitrogenative transannulation reaction of pyridotriazoles with terminal alkynes en route to indolizines was developed. Compared to the previously reported Rh-catalyzed transannulation reaction, this Cu-catalyzed method features aerobic conditions and much broader scope of pyridotriazoles and alkynes.