Photocyclization of N-Phenyl-1-Naphthamides

Photocyclization of N-Phenyl-1-Naphthamides

Author: ChemistryViews

Dehydrogenative 6π photocyclization reactions can be useful tools for the synthesis of polycyclic aromatic systems. They can lead to, e.g., natural products or pharmaceutically active species. Benzophenanthridinone derivatives such as 6-methylbenzo[i]phenanthridin-5(6H)-one (pictured), for example, are interesting targets in medicinal chemistry.

Xiaoying Niu, Xiu-Long Yang, Hebei University, Baoding, China, Qing-Yuan Meng, Beijing National Laboratory for Molecular Sciences and University of Chinese Academy of Sciences, Beijing, China, and colleagues have developed a method for the dehydrogenative 6π photocyclization of N-substituted naphthalene carboxamides that gives benzo[i]phenanthridin-5(6H)-ones. The team started from different N-phenyl-1-naphthamides, which were dissolved in dimethyl sulfoxide (DMSO) and subjected to purple light irradiation (405–410 nm) at room temperature under air.

Under these conditions, without any photosensitizers or additives, a broad range of N-phenyl-1-naphthamides were cyclized to give the desired products in moderate to high yields. The reaction was successfully performed on a gram scale, giving a yield of 84 %. According to the team, DMSO serves as both solvent and oxidant in the transformation. 


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