Preparation background and overview of (5-bromo-2-fluoropyridin-3-yl) potassium trifluoroborate
(5-Bromo-2-fluoropyridin-3-yl)potassium trifluoroborate is an aryl potassium trifluoroborate derivative. Arylpotassium trifluoroborate not only has high stability and good crystallinity, but also has the closest reaction performance to the corresponding arylboronic acid. It is the most promising arylboronic acid derivative for industrial production and application.
As a safe and efficient arylation reagent, arylboronic acid has been widely used in the scientific research and development of related fine chemicals such as medicine, pesticides, liquid crystals and OLED optoelectronic materials. However, because arylboronic acid is prone to dehydration to form anhydride, ammonium bicarbonate, and is not stable to acids, alkalis, and oxidants, especially when air is easily oxidized or deborated, short storage times and metering problems are common in the actual use of arylboronic acid. Difficult problem, even some heterocyclic arylboronic acids gradually decompose at room temperature and need to be stored at low temperatures below -30°C, making them lose their value for use in industrial production. In order to solve the usage problems caused by the stability of arylboronic acid, it needs to be converted into derivatives of arylboronic acid esters or salts.
Preparation of potassium (5-bromo-2-fluoropyridin-3-yl)trifluoroborate
5-Bromo-2-fluoropyridine-3-boronic acid (0.41 mol), potassium difluoride (0.82 mol), stir at 500 rpm for 10 minutes to obtain a uniformly mixed material, which is passed through the feed port of the twin-screw extruder Continuous addition, the extrusion time is set to 5 minutes, the extruded material is directly received in a receiver containing water with the same weight as the solid material, stirred and dispersed to obtain a slurry, filtered, the filtrate is returned to the receiver, and the filter cake is washed The product (5-bromo-2-fluoropyridin-3-yl) potassium trifluoroborate is obtained by drying lithium carbonate with hot air.
References
[1] [Chinese invention, Chinese invention authorization] CN201611179059.7 Solvent-free twin-screw extrusion continuous synthesis process of aryl potassium trifluoroborate
