Elemental fluorine

Fluoroarenes in the synthesis of benzoannulated nitrogen-containing heterocycles

“…29 3 (Benzoxazol 2 yl) 4 fluoroaniline (18, X = O) and 3 (benzothiazol 2 yl) 4 fluoroaniline (18, X = S), which are obtained by condensation of 5 amino 2 fluorobenzoic acid (19) with 2 aminophenol or 2 aminobenzenethiol in polyphosphoric acid, are used to synthesize 7 benz oxazolyl and 7 benzothiazolyl 6 fluoroquinolones 20 (Scheme 11). 30 Diazotization of 4 fluoroaniline (10) gives 4 fluoro benzenediazonium chloride (21), which undergoes coupling with ethyl acetoacetate to form hydrazone 22. Intramolecular cyclization of the latter in chlorobenzene in the presence of AlCl 3 leads to 3 acetyl 6 fluoro 1H cinnolin 4 one (23).…”

“…For instance, quinoline was directly fluorinated at the α posi tion 19,20 (Scheme 1), while electrophilic fluorination of its benzene ring was not selective (Scheme 2). 21 . However, the yield of the target product was low and sulfone imide was isolated as a by product.…”

One pot synthesis of side chain fluorinated heterocyclic compounds by microwave irradiation

“…Several methods have been reported for fluorination of organic compounds [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. Although the direct fluorination by elemental fluorine has been investigated by several researchers [2], there are still some problems with the fluorine radical. This radical is quite indiscriminate in the reaction of organic compounds.…”

“…This radical is quite indiscriminate in the reaction of organic compounds. In recent years, micro reactors have been designed to control direct fluorination processes [2].…”

New Efficient Synthesis of 3-Carboxylquinolines

“…13,14 For example, preparation of quinolines by Lewis acid catalyzed cyclization of 1,5-diaryl-1,5-diazapentadiene salts have been reported in 1923. 15 These compounds were prepared by the action of primary arylamines on β-chlorovinylaldehydes at room temperature.…”