Scalable Synthesis of Benzotriazoles via [3+2] Cycloaddition of Azides and Arynes in Flow

Abstract

A method for the metal-free synthesis of benzotriazoles in flow is reported. Using azides and in situ generated arynes, benzotriazoles are formed in a [3+2] cycloaddition within minutes. Employing different substitution patterns of the azide and aryne coupling partners, a modular access to benzotriazoles is provided. Thermal strain of hazardous azides and accumulation of reactive intermediates is minimized by short reaction times in flow, improving the safety profile of the process. The scalability of the reaction is demonstrated.