Handling Hazards Using Continuous Flow Chemistry: Synthesis of N1-Aryl-[1,2,3]-triazoles from Anilines via Telescoped Three-Step Diazotization, Azidodediazotization, and [3 + 2] Dipolar Cycloaddition Processes

Abstract

The conversion of commercially available anilines into triazole products was realized using a telescoped three-reactor flow diazotization, azidodediazotization, and [3 + 2] dipolar cycloaddition process. The diazotization–azidodediazotization sequence was accelerated by means of an ultrasonic bath resulting in a degassed, segmented effluent. An automated continuous flow unit controlled by custom software created in-house was used to collect the aryl azide stream and restore it to a continuous column of the reagent. When combined with a variety of dipolarophiles, 1-aryl-[1,2,3]-triazoles were thus assembled by either copper catalyzed alkyne–azide cycloaddition (CuAAC) or Huisgen cycloaddition reactions.