1-(Imidazol-1-yl)-indolizines—two-step synthesis and optical properties

A one-pot process leading to complex aromatic heterocyclic compounds has been designed. Kröhnke methodology has been used to synthesize indolizines bearing an aldimino-substituent at position 1. Further reaction of these compounds with 1,2-diketones and ammonium acetate led to tetra-substituted imidazoles in 5–28% overall yield. The resulting compounds display strong absorption of UV radiation and emission of a blue light accompanied with large Stokes shifts. Replacing the aryl substituents with thiophene at position 3 of the indolizine and position 2 of the imidazole produce a further red shift of the absorption (vs products with substituted benzene rings) as a result of a more planar conformation in the ground state.