Diazonium salts Baltz-Schiemann reaction

The most widely used method for the substitution of nitrogen-containing functional groups by fluorine is the thermal or photochemical decomposition of diazonium salts, the Baltz-Schiemann reaction (see Section 1.1.8 ). 

One of the typical examples of the Baltz-Schiemann reaction is synthesis of fluoro-substituted pyridines 26 from aminopyridines 25 (Scheme 6.10). In this variation, the Baltz-Schiemann reaction is most often used for the synthesis of 2-fluoropyridines. In the first step, a diazonium tetrafluoroborate is generated from 2-aminopyridine, NaN02, and solution of HF and BF3 (HBF4), while subsequent thermal decomposition of the diazonium salt leads to formation of 2-fluoropyridines. In this chapter, we present several literature examples of synthesis of 2-fluoropyridines and examples of specific use of the Baltz-Schiemann reaction for preparation of biologically active derivatives of 2-fluoropyridines. 

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See also in sourсe #XX -- [ ]

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