Synthesis of Luminescent Indolo[2,1- b ]quinazolin-6(12 H )-ones via a Sequential Ugi/Iodine-Promoted Cyclization/Staudinger/Aza-Wittig Reaction.

A new efficient synthesis of indolo[2,1- b ]quinazolin-6(12 H )-ones via a sequential Ugi/iodine-promoted cyclization/Staudinger/aza-Wittig reaction was developed. The acid catalyzed three-component reactions of 2-azidobenzaldehydes, 2-[2-(trimethylsilyl)ethynyl]benzenamines (or o -aminoacetophenones), and isocyanides gave Ugi-3CR intermediates, which reacted subsequently with I 2 /DMSO and triphenylphosphine to produce indolo[2,1- b ]quinazolin-6(12 H )-ones in good overall yields. The obtained indolo[2,1- b ]quinazolin-6(12 H )-ones were all colored in bright red or orange. Their luminescent property was studied preliminarily and some of them showed high molar absorption coefficients, strong fluorescence emission intensity, and good absolute light quantum yields.