A one-pot oxygen-annulation couples chloroquinones with aromatic alcohols to efficiently construct π-expanded furans in yields up to 91%. Subsequent TIPS-acetylene functionalization and reductive aromatization enhance solubility and furnish bench-stable chromophores that absorb in the blue and exhibit strong fluorescence. Time-dependent density functional theory (TD-DFT) reveals low-energy, charge-transfer excitations in the quinone intermediates, which shift to higher-energy, localized π-π* transitions upon aromatization. Remarkably, these π-expanded furans withstand UV irradiation over 10-fold longer than TIPS-pentacene, highlighting their exceptional photostability.
Pareek et al. (Mon,) studied this question.