Dehydrogenation Coupling and [3 + 2] Cycloaddition of Indolizines with Allenes in the Presence of Piezoelectric Materials under Ball Milling Conditions.

A wide range of indolizines with allenes proceeded smoothly under mechanochemical-induced conditions via [3 + 2] annulation process, affording various substituted pyrrolo[2,1,5- cd ]indolizines with good yield. The reaction efficiency was greatly improved by using a piezoelectric material as the charge transfer catalyst. The photophysical properties of the resulting pyrrolo[2,1,5- cd ]indolizine was characterized.