Selectfluor-triggered fluorination/cyclization of o-hydroxyarylenaminones: A facile access to 3-fluoro-chromones

Abstract

A fast and efficient Selectfluor-triggered fluorination/cyclization reaction of o-hydroxyarylenaminones has been successfully developed. The reaction successfully provides an expedient method for the synthesis of 3-fluoro-chromones promoted by potassium carbonate, which shows readily available starting materials and is easy to operate. In addition, a plausible mechanism of this tandem cyclization reaction was proposed where 4 H-chromen-4-one, 2-(dimethylamino)-3,3-difluorochroman-4-one, and 3,3-difluoro-2-hydroxychroman-4-one were not found to be the reactive intermediates. Moreover, these novel compounds have been obtained in moderate to good yields, and their structures have been confirmed by 1H NMR, 13C NMR, and high-resolution mass spectrometry.

3‐Halochromones Through Oxidative α‐Halogenation of Enaminones and its Photophysical Investigation: Another Case of Photo‐induced Partially Aromatised Intramolecular Charge Transfer?

“…[4][5] The presence of halogen atoms in position 3 of the chromone allows its conversion to 2-or 3-substituted chromones, [6][7][8][9] as well as the synthesis of other oxygen-containing heterocycles such as coumarones, chromanones, and furans and nitrogen-containing heterocycles such as imidazoles, pyrroles, pyrimidines, and pyridines. [10] The synthesis of 3-halochromones is usually performed from enaminones [11][12][13][14][15][16][17] due to their easy availability and good shelf stability. [18] The protocols provide an in situ electrophilic halogen species employing N-chlorosuccinimide (NCS) or N-bromosuccinimide (NBS), [12] HX/DMSO, [13] KX/PhI(OAc) 2 , [14] electrochemical oxidation of NaX [15] or other halogen sources as Br 2 [11] or t-butyl hypochlorite, [11] as depicted in Scheme 1.…”

Electrochemical C-H Halogenations of Enaminones and Electron-Rich Arenes with Sodium Halide (NaX) as Halogen Source for the Synthesis of 3-Halochromones and Haloarenes

“…In 1979, Gammill reported the 3-halochromone synthesis by employing molecular halogen via a two-step operation. Later, the hydrogen halide (HX), iodine chloride (ICl), and Selectfluor have also been used as halogen source for the synthesis of 3-halogenated chromones, respectively. In 2020, our group has also attempted the synthesis of 3-halochromones by using potassium halide (KX) as halogen source via a chemical oxidation tactic .…”