Solid-State Melt Rearrangement of Azidofluorenes for the Synthesis of Phenanthridine Derivatives

Abstract

Phenanthridines are prevalent core in several natural products and staining agents that could be assembled in various manners. However, to our knowledge, the skeletal editing of azides via solid-state melt rearrangement (SSMR) without catalysts, bases, and additives to access phenanthridines is not reported in the literature. Herein, we report solvent-free and catalyst-free thermolytic SSMR of azidofluorenes to phenanthridine derivatives. This protocol successfully demonstrates 21 examples of phenanthridines by SSMR of symmetrical and unsymmetrical azidofluorenes in good to excellent yields. The green metrics of the developed protocol are in good accordance with ideal green chemistry metrics.