Synthesis, photophysical and redox properties of the 2,5,7-tri(het)aryl-[1,2,4]triazolo[1,5-a]pyrimidines

Abstract

A number of Y-type push-pull compounds based on the [1,2,4]triazolo[1,5-a]pyrimidine core, namely 5,7di(het)aryl-substituted 2-phenyl-[1,2,4]triazolo[1,5-a]pyrimidines, were obtained by transition metal free nucleophilic C-H functionalization. Substituents at both the C-5 and C-7 positions were introduced by successive treatment of the starting 6-bromo-2-phenyl-[1,2,4]triazolo[1,5-a]pyrimidine with Grignard reagents. In addition, the optical and electrochemical properties of the synthesized push-pull systems were studied.

Direct C7‐H Arylation of Pyrazolo[1,5‐a]azines with Aryl Chlorides

“…The authors have cited additional references within the Supporting Information. [23][24][25][26][27]…”

Ethynylation of [1,2,4]Triazolo[1,5‐a]pyrimidinesUsing Substituted Ethynylmagnesium Bromides

“…Considering our previous success of the addition of Grignard reagents to TAPs systems, [16] we decided to explore similar reaction with magnesium salts of mono-substituted acetylenes. Based on the 1 H and 13 C NMR spectra of compounds 3 and 4, the most electron-deficient position in both cases is C-7, therefore, a more preferable target for the attack of the nucteophile than the C-5 position of TAP. Indeed, the addition of ethynylmagnesium bromides to TAP 3 in THF solution at À 20°C proceeded smoothly regioselectively, thus giving corresponding N-magnesium salts of 7-substituted TAP σ H -adducts 5*a-c.…”

“…Description of the all procedures for obtaining ethynylated TAPs, copies of their 13 C and 1 H NMR spectra, FTIR spectroscopy data, absorption, excitation and emission spectra and CV curves available in Supporting Information. Deposition Numbers 2071318 (for 6c), 2071317 (for 12 bc) contains the supplementary crystallographic data for this paper.…”

“…Recently, we have described an effective synthetic route towards (hetero)aryl-substituted TAPs based on the transition-metal-free method of nucleophilic hydrogen substitution [12] as well as luminescent and electrochemical properties of the these π-extended TAPs have been investigated. [13] In this work we want to present a transitionmetal-free method for the preparation of 5,7-bis(ethynyl)-substituted TAPs by direct addition of ethynylmagnesium bromides.…”