A combined experimental and theoretical study of the thermal cycloaddition of aryl azides with activated alkenes

Abstract

Reactions were performed from aryl azides on the one hand, and activated alkenes coming from β-dicarbonyl compounds or malonodinitrile on the other hand, either with recourse to conventional heating or to microwave activation, to afford 1-aryl-1H-1,2,3-triazoles. The mechanism and the regioselectivity of the reactions involving β-dicarbonyl compounds have been theoretically studied using DFT methods at the B3LYP/6-31G* level: they are domino processes comprising a tautomeric equilibrium of the β-dicarbonyl compounds with their enol forms, a 1,3-dipolar cycloaddition of the enol forms with the aryl azides (high activation energy), and a dehydration process (lower activation energy). The effect of non-conventional activation methods on the degradation of 1,2,3-triazolines was next studied experimentally. Finally, some of the 1,2,3-triazoles such synthesized were evaluated for their bactericidal and cytotoxic activities.

Catalytic behavior of surfactant-containing-MCM-41 mesoporous materials for cycloaddition of 4-nitrophenyl azide

“…homogeneous [50], heterogeneous and mixed homogeneous/heterogeneous catalysts. Concerning the latter two catalysts, the reaction time and product yields of 3a-c have been improved in the following order: heterogeneous catalyst > mixed catalyst > homogeneous catalyst and, for the products 3d and 3e, the homogeneous/heterogeneous catalysis was superior than the catalysts used individually.…”

“…After removal of the solvent, the crude product was recrystallized from iPrOH. Characterization data associated with this article have been previously described [50], except in the case of 3c. …”

“…The reaction proved regioselective. The assignment of the stereochemistry was established by NMR (NOESY, HMBC, and HMQC) and was confirmed by XRD [50]. Table 3 depicts the results using both homogeneous (Et 3 N) and heterogeneous (MCM-41) basic catalysts.…”

“…Otherwise, triethylamine is at the origin of the irreversible water elimination step [50]. The latter may displace the reaction toward the formation of the final triazole, and thus help to perform more difficult reactions such as that giving 3e (absence of intramolecular hydrogen bond to favor the enimine form).…”

Synthesis of 1,2,3-Triazole Derivatives and Its Evaluation as Corrosion Inhibitors for Carbon Steel

“…The copper-catalyzed 1,3-dipolar cycloaddition reaction between an azide and an alkyne is widely used for the synthesis of compounds with the 1,2,3-triazole ring with substituents in position 4 [12]. Other methodology for the synthesis of this class of compounds is the reaction of an azide with methylenic activated compounds, using different catalysts generating a triazol with substituents in positions 4 and 5 [13].…”