Selective radical amination of aldehydic C(sp²)–H bonds with fluoroaryl azides via Co(<scp>ii</scp>)-based metalloradical catalysis: synthesis of N-fluoroaryl amides from aldehydes under neutral and nonoxidative conditions

Abstract

The Co(II) complex of the <i>D</i>_2h-symmetric amidoporphyrin 3,5-Di <i>^t</i> Bu-IbuPhyrin, [Co(<b>P1</b>)], has proven to be an effective metalloradical catalyst for intermolecular amination of C(sp²)-H bonds of aldehydes with fluoroaryl azides. The [Co(<b>P1</b>)]-catalyzed process can employ aldehydes as the limiting reagents and operate under neutral and non-oxidative conditions, generating nitrogen gas as the only byproduct. The metalloradical aldehydic C-H amination is suitable for different combinations of aldehydes and fluoroaryl azides, producing the corresponding <i>N</i>-fluoroaryl amides in good to excellent yields. A series of mechanistic studies support a stepwise radical mechanism for the Co(II)-catalyzed intermolecular C-H amination.