Synthesis of triazene-substituted homoconjugated push-pull chromophores by formal [2 + 2] cycloadditions

Abstract 1-(4-Ethynylphenyl)-3,3-dialkyltriaz-1-enes, well-known building blocks for branched dendrimer syntheses, were utilized as a new type of electron-donor component in formal [2 + 2] cycloadditions. The click-type, atom-economic reactions proceed efficiently under ambient conditions without any catalyst. The resulting products are structurally interesting push-pull chromophores and were investigated in the context of optoelectronic properties using UV/Vis spectroscopy, NMR studies, and computational chemistry.