Synthesis of Helquats Based on Phenanthridinium Units: Four-Step Procedure to Novel Extended Helical Dications

Abstract

Three novel helical dications (helquats) containing phenanthridinium units have been synthesized from 6-(pyridin-2-ylethynyl)phenanthridine as a common precursor prepared by Sonogashira coupling of phenanthridin-6-yl triflate with 2-ethynylpyridine. Bisquaternization of the common precursor followed by rhodium-catalyzed [2+2+2] cycloisomerization led to the title helical dicationic scaffolds. The connectivity and spatial arrangement of the three target helquats were unambiguously established by X-ray crystal structure analysis.

Ambient Temperature Dehydrogenative C(Ar)–H Carbonylative Lactamization of 2-Arylanilines Using DMF as C1-Source

“…Phenanthridinones are significant and privileged structural units that widely occur in biologically active alkaloid natural products and pharmaceuticals . These moieties display a broad range of biological activities, such as antitumor activity, antiviral activity, and cytotoxicity . Accordingly, the development of practical synthetic strategies for constructing such molecular skeletons has been attractive to chemists.…”