2H-Bis-1,2,3-triazolo-isoquinoline: Design, Synthesis, and Photophysical Study

A transition-metal-free azide-alkyne cycloaddition/hydroamination cascade reaction for the construction of triazole-fused piperazin-2-ones

A time-dependent, divergent synthesis of highly functionalized [1,2,3]triazolo[1,5-a]pyrazin-4(5H)-one (reaction time: 12 h) or 6,7-dihydro-[1,2,3]triazolo[1,5-a]pyrazin-4(5H)-one (reaction time: 2 h) scaffolds via a cascade azide-alkyne cycloaddition/hydroamination protocol is reported. The transformation features good functional group compatibility, broad substrate scope, high atom economy and avoidance of the use of transition-metal catalysts.

Copper(I)-Catalyzed Radical Carbamylation/Cyclization of 2-Aryl-N-methacryloylindoles with Substituted Formamides to Assemble Amidated Indolo[2,1-a]isoquinolin-6(5H)-ones

An efficient synthesis of amidated indolo[2,1-a]isoquinolin-6(5H)-ones has been achieved via copper(I)-catalyzed radical carbamylation/cyclization of 2-aryl-N-methacryloylindoles with substituted formamides. In this reaction, an isoquinoline ring was constructed by carbamylation of a carbon-carbon double bond in 2-arylindoles. This strategy successfully introduces the substituted amide group into the indolo[2,1-a]isoquinoline skeleton and has advantages such as wide substituent scope, mild reaction conditions, high regioselectivity, and good to excellent yields.

An Unusual Rearrangement of Pyrazole Nitrene and Coarctate Ring-Opening/Recyclization Cascade: Formal CH-Acetoxylation and Azide/Amine Conversion without External Oxidants and Reductants

We report an unusual transformation where the transient formation of a nitrene moiety initiates a sequence of steps leading to remote oxidative C-H functionalization (R-CH3 to R-CH2OC(O)R') and the concomitant reduction of the nitrene into an amino group. No external oxidants or reductants are needed for this formal molecular comproportionation. Detected and isolated intermediates and computational analysis suggest that the process occurs with pyrazole ring opening and recyclization.

Acid-Switchable Synthesis of Trifluoromethylated Triazoles and Isoxazoles via Reaction of CF3-Ynones with NaN3: DFT Study of the Reaction Mechanism

A detailed study of the reaction of CF₃-ynones with NaN₃ was performed. It was found that the reaction permits the selective synthesis of either 4-trifluoroacetyltriazoles or 5-CF₃-isoxazoles. The chemoselectivity of the reaction was switchable via acid catalysis. The reaction of CF₃-ynones with NaN₃ in EtOH produced high yields of 4-trifluoroacetyltriazoles. In contrast, the formation of 5-CF₃-isoxazoles was observed under catalysis by acids. This acid-switchable procedure can be performed at sub-gram scale. The possible reaction mechanism was supported by DFT calculations. The synthetic utility of the prepared 4-trifluoroacetyltriazoles was demonstrated.

Synthesis of blue light emitting heterocycles via cyclization of 2-pyridine derived 4-azido-r1,2,3-triazoles

An efficient synthesis of 2-pyridine derived 4-azido-1,2,3-triazoles was elaborated using the corresponding dichlorodiazadienes as precursors. The reaction of the prepared 2-azine substituted diazadienes with sodium azide permits the preparation of target triazoles isolated in up to 92% yield. Subsequent thermal cyclization was studied. Elimination of molecular nitrogen promoted the cyclization of nitrene at the azine nitrogen. As a result, a family of 2H-[1,2,3]triazolo[4',5':3,4]pyrazolo[1,5-a]pyridin-5-ium-4-ides was prepared. The synthesized compounds are members of a new heterocyclic system. Moreover, these compounds are new attractive blue light emitting molecules.

C(sp2) – H functionalization of aldimines and related compounds: advances and prospects

This is the first systematic review of the most relevant approaches to direct C(sp2)–H bond functionalization of azomethine derivatives. The scope of the applicability of various transformations is analyzed. The review assesses prospects of the application of this functionalization strategy in the multistep synthesis of valuable compounds for use in medicinal chemistry, materials science and related areas.

The bibliography includes 124 references.