Pnictogen bonding enabled photosynthesis of chiral selenium-containing pyridines from pyridylphosphonium salts

Abstract

Pyridylphosphonium salts, which are readily available and air and thermally stable, have been used to effectively synthesize structurally diverse pyridines. Herein, we report the pnictogen bonding (PnB) enabled photoactivation of pyridylphosphonium salts with catalytic potassium carbonate to generate pyridyl radical for pyridine synthesis. Remarkably, this light-driven transformation allowed chiral pool synthesis with excellent chirality retention, giving a wide range of chiral selenium-containing pyridines. On the basis of our combined computational and experimental studies, we propose that the PnB between pyridylphosphonium salts and potassium carbonate enables access to the photoactive charge transfer complex, which is able to undergo single electron transfer to generate pyridyl radical for its transformation.

Keywords

• Pyridylphosphonium salts
• Visible light-induced synthesis
• Selenium-containing pyridines
• Pnictogen bonding
• Charge transfer complex