Mechanochemically Induced Dehydrogenation Coupling and [3+2] Cycloaddition of Indolizines with Allenes Using Piezoelectric Materials

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