I2/H2O2 mediated synthesis and photophysical properties of imidazole-fused heterocycles via [4+1] cyclization approach

• DOI: 10.3762/bxiv.2024.8.v1
• Publication Date: 2024-02-07T08:19:52Z
• Authors: Haonan Li; Chenping Gao; Qingjie Liu; Yanchun Guo; Shuxia Cao; Yufen Zhao

An efficient I2 (10 mmol%)/H2O2 mediated oxidative formal [4+1] cyclization of 2-pyridinemethylamine or o-phenylenediamine (2-aminobenzenethiol) with benzaldehyde via C-N bond formation has been developed. This strategy offers a straightforward approach to imidazo[1,5-a]pyridine and benzimidazole (benzothiazole) derivatives in 65% to 98% yields. Several heterocyclic products exhibit promising blue luminous performance with satisfactory fluorescence quantum yields of up to 64%, large Stokes shifts, and a longer lifetime (7.35 ns). The band gap energies obtained from DFT are also consistent with the absorption spectra.