Synthesis of Triazatriphenylene Derivative Through Multi‐Component Reaction of Aryl‐amine, Aldehyde, and Alkyne

Abstract

AbstractThe Povarov reaction is a representative multicomponent reaction used for synthesizing nitrogen‐containing aromatic compounds from aromatic amines, aldehydes, and dienophiles, such as electron‐rich alkenes and alkynes. In this study, we investigated a triple Povarov reaction of 1,3,5‐triaminobenzne with aromatic aldehydes and phenylacetylene to obtain triazatriphenylene derivatives. Reactions with arylaldehydes containing electron‐donating groups proceeded smoothly to provide triazatriphenylene derivatives. In contrast, reactions with arylaldehydes containing electron‐withdrawing groups resulted in low yields. Reactions with electron‐rich arylaldehydes are probably more favorable in terms of high stability of imine intermediates and smooth electrophilic cyclization. Single‐crystal X‐ray structure analysis revealed that the aryl groups derived from the aldehydes had small dihedral angles between with the triazatriphenylene core. The derivative with tertiary butyl groups (tBu‐TaT) had a high glass transition temperature, while that without tertiary butyl groups (H‐TaT) had a lower highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) level and served as an efficient hole‐blocking material with better electron transport properties than those of tBu‐TaT. This study provides insights into the scope and limitations of the multicomponent reactions based on the Povarov reaction, substituent dependence on the crystal structures, and physical properties of π‐extended nitrogen‐containing aromatic compounds.