Investigations on the continuous flow generation of 2,6-dichloro-N-fluoropyridinium tetrafluoroborate using F2 gas

Abstract

An explorative study on the continuous flow generation of the N-F reagent 2,6-dichloro-1-fluoro-pyridinium tetrafluoroborate from 2-6-dichloropyridine and 10% F₂/N₂ and its telescoped downstream electrophilic fluorination reaction with an enamine is reported. The 2-step procedure was performed in a modular lab-scale silicon carbide flow reactor, which safely allowed processing corrosive F₂ and precise temperature control. Both reaction sequences turned out to be very fast when carried out in flow at − 10 °C: the N-F generation step could be done within 7.9 s and only 6.6 s were necessary for the fluorination of the enamine.

Graphical abstract