La(OTf)3-catalysed one-pot synthesis of pyrazole tethered imidazo[1,2-a]azine derivatives and evaluation of their light emitting properties

Abstract

A facile and efficient protocol has been unfolded towards the diversity-oriented synthesis of highly fluorescent pyrazole C-3(5) tethered imidazo[1,2-a]azines via an La(OTf)₃ catalysed one-pot multicomponent assembly of pyrazole carbaldehydes, 2-aminoazines and isonitriles. This present protocol offers several advantages such as multiple bond formation in a single step, low catalyst loading, short reaction time, appreciable atom economy, good functional group tolerance, scalability and easy to perform reaction conditions. The optical properties of pyrazolyl imidazo[1,2-a]azines were also studied, and they exhibited an excellent fluorescence quantum yield (Φ_F up to 83%).