- Expanding the Balz–Schiemann Reaction: Organotrifluoroborates Serve as Competent Sources of Fluoride Ion for Fluoro-Dediazoniation
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The Balz–Schiemann reaction endures as a method for the preparation of (hetero)aryl fluorides yet is eschewed due to the need for harsh conditions or high temperatures along with the need to isolate potentially explosive diazonium salts. In a departure from these conditions, we show that various organotrifluoroborates (RBF3?s) may serve as fluoride ion sources for solution-phase fluoro-dediazoniation in organic solvents under mild conditions. This methodology was successfully extended to a one-pot process obviating aryl diazonium salt isolation. Sterically hindered (hetero)anilines are fluorinated under unprecedentedly mild conditions in good-to-excellent yields. Taken together, this work expands the repertoire of RBF3?s to act as fluorine ion sources in an update to the classic Balz–Schiemann reaction.
- Mohy El Dine, Tharwat,Sadek, Omar,Gras, Emmanuel,Perrin, David M.
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supporting information
p. 14933 - 14937
(2018/09/25)
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- Rapid Synthesis of Aryl Fluorides in Continuous Flow through the Balz–Schiemann Reaction
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The Balz–Schiemann reaction remains a highly utilized means for preparing aryl fluorides from anilines. However, the limitations associated with handling aryl diazonium salts often hinder both the substrate scope and scalability of this reaction. To address this, a new continuous flow protocol was developed that eliminates the need to isolate the aryl diazonium salts. The new process has enabled the fluorination of an array of aryl and heteroaryl amines.
- Park, Nathaniel H.,Senter, Timothy J.,Buchwald, Stephen L.
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supporting information
p. 11907 - 11911
(2016/11/17)
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- 167. Dediazoniation of Arenediazonium Ions. Part XXII. Reactions of 2,6-Dialkyl-Substituted Benzenediazonium Ions in Super Acids. Acetonitrile and Acetone
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Reactions of 2,4,6-trimethylbenzenediazonium (1), 2,6-diethylbenzenediazonium (2) and 2,6-diisopropylbenzenediazonium (3) tetrafluoroborates were studied in magic acid, SbF5/SO2ClF, acetonitrile and acetone by 1H-NMR and by analysis of the dediazoniation products.The Nα-Nβ rearrangement of β-N15-labelled tetrafluoroborates 1-3 was followed by 15N-NMR of the corresponding arylazonaphthols, as well as by MS analysis of the anilines obtained by reduction of the azo compounds.Diazonium salts 2 and 3 were synthesized for the first time and the steric effect substituents at C(2) and C(6) on the reactions under study is discussed.All the results obtained can be rationalized by heterolytic dediazoniation of diazonium salts 1-3 and product formation from the corresponding aryl cations.
- Laali, Khosrow,Szele, Ivanka,Zollinger, Heinrich
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p. 1737 - 1747
(2007/10/02)
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