Ultrasound-promoted regioselective synthesis of chalcogeno-indolizines by a stepwise 1,3-dipolar cycloaddition

Abstract

A series of new organochalcogen derivatives of indolizines was synthesized in moderate to excellent yields from pyridinium salts and chalcogeno-alkynes. The reaction can be carried out under thermal conditions or by sonochemical processes in short reaction times. The stepwise cycloaddition reaction forming chalcogeno-indolizines is regioselective and extends to a broad range of functional groups. Furthermore, novel chalcogeno-alkynes are reported and the first derivatives of teluro-indolizine are described. The influence of selenium functionalization on the photophysical properties of indolizines is also described, in which the compounds showed absorption in the UV–Vis region around 360 nm and emission in the blue-to-green region. Relatively low fluorescence quantum yield (ϕfl) values were calculated, in agreement with the chalcogen effect on other heterocycles.