title: Pressure-accelerated azide-alkyne cycloaddition: micro capillary versus autoclave reactor performance.
abstract: Pressure effects on regioselectivity and yield of cycloaddition reactions have been shown to exist. Nevertheless, high pressure synthetic applications with subsequent benefits in the production of natural products are limited by the general availability of the equipment. In addition, the virtues and limitations of microflow equipment under standard conditions are well established. Herein, we apply novel-process-window (NPWs) principles, such as intensification of intrinsic kinetics of a reaction using high temperature, pressure, and concentration, on azide-alkyne cycloaddition towards synthesis of Rufinamide precursor. We applied three main activation methods (i.e., uncatalyzed batch, uncatalyzed flow, and catalyzed flow) on uncatalyzed and catalyzed azide-alkyne cycloaddition. We compare the performance of two reactors, a specialized autoclave batch reactor for high-pressure operation up to 1800 bar and a capillary flow reactor (up to 400 bar). A differentiated and comprehensive picture is given for the two reactors and the three methods of activation. Reaction speedup and consequent increases in space-time yields is achieved, while the process window for favorable operation to selectively produce Rufinamide precursor in good yields is widened. The best conditions thus determined are applied to several azide-alkyne cycloadditions to widen the scope of the presented methodology.
authors.affiliation: Department of Chemical Engineering and Chemistry, Micro Flow Chemistry and Process Technology, Eindhoven University of Technology, Den Dolech 2, 5612AZ, Eindhoven (The Netherlands).
authors.forename: Svetlana
authors.initials: S
authors.lastname: Borukhova
authors.forename: Andreas D
authors.initials: AD
authors.lastname: Seeger
authors.forename: Timothy
authors.initials: T
authors.lastname: Noël
authors.forename: Qi
authors.initials: Q
authors.lastname: Wang
authors.forename: Markus
authors.initials: M
authors.lastname: Busch
authors.forename: Volker
authors.initials: V
authors.lastname: Hessel
mesh_terms: D000480:Alkynes / Q000737:chemistry*; D001386:Azides / Q000737:chemistry*; D002384:Catalysis; D061565:Cycloaddition Reaction / Q000295:instrumentation*; D007700:Kinetics; D011312:Pressure; D013237:Stereoisomerism; D013696:Temperature
chemical_list: D000480:Alkynes; D001386:Azides
keywords: 1,3-dipolar cycloaddition; high pressure; microflow chemistry; novel process windows; rufinamide