Fluoroaromatics from Arylamines, a Convenient One-Pot Conversion Using Nitrosonium Tetrafluoroborate

Conversion of Benzal Halides to Benzaldehydes in the Presence of Aqueous Dimethylamine

“…When the reactions of 19 and 24 were extended to 2 hours, substitution of the corresponding p-fluoro groups by dimethylamine occurred in good yield (>80%). At least an hour was required for complete conversions of 25 and 27 to aldehydes 26 22,23 and 28, 13,19,24 respectively. Extending the reaction time to 8 hours completely converted 27 to 29 (94%) 25,26 but substitution of 25 by dimethylamine to give 26a 27 was never observed (Scheme 5).…”

“…experiment, in which 4-fluorobenzal chloride(24), 3-fluorobenzal chloride(25) and 2-fluorobenzal chloride(27) were reacted together with aqueous dimethylamine at 60°C for an hour, provided interesting results. The conversion rate of 24 was the fastest, as expected.…”

Balz-Schiemann Reaction

“…The risk on spontaneous and/or violent decomposition of arenediazonium tetrafluorobarates is a major safety concern of Balz-Schiemann reaction. To avoid the isolation and drying of arenediazonium tetrafluoroborates, other diazotization reagents such as NOBF 4 [10] and the combination of tBuONO/BF 3 ÁEt 2 O [11] have been used for diazoniation in organic systems, and thus anilines can be transformed into aryl fluorides in one pot.…”

Where Does the Fluorine Come From? A Review on the Challenges Associated with the Synthesis of Organofluorine Compounds

“…Aside from the HALEX reaction, one of the most common methods is the Balz–Schiemann reaction where an aniline is diazotized and decomposed with heat or light in the presence of a fluoride source, namely, tetrafluoroborate or hexafluorophosphate (Scheme ). ,− While the reaction reliably provides the desired fluoroarene, its limitations include the availability of starting aniline and the inherent instability and often explosivity of the diazo intermediate.…”