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

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

Scalable Synthesis of Functionalized Ferrocenyl Azides and Amines Enabled by Flow Chemistry

A scalable access to functionalized 1,1’- and 1,2-ferrocenyl azides has been realized in flow. By halogen‒lithium exchange of ferrocenyl halides and subsequent reaction with tosyl azide, a variety of functionalized ferrocenyl azides was obtained in high yields. To allow a scalable preparation of these potentially explosive compounds, an efficient flow protocol was developed accelerating the reaction time to minutes and circumventing accumulation of potentially hazardous intermediates. Switching from homogeneous to triphasic flow amidst process was key for handling a heterogeneous reaction mixture formed after a heated reactor section. The corresponding and synthetically versatile ferrocenyl amines were then prepared by a reliable reduction process