Talik, Zofia published the artcile2,6-Dimethyl-3-fluoro-4-nitropyridine N-oxide, Category: pyridine-derivatives, the publication is Roczniki Chemii (1965), 39(4), 601-6, database is CAplus.
Reactivity of the fluorine atom in I was found to be lower than in the 3-fluoro-4-nitropyridine N-oxide. A series of substitution reactions of F or NO2-group was carried out. A mixture of 25 g. 2,6-dimethyl-3-aminopyridine in 150 ml. EtOH, 150 ml. HBF4, prepared from 140 ml. 48% HF and 45 g. H3BO3, was treated at 0°, during 90 min. with EtONO, kept 10 min. at 50°, cooled to 0°, treated again during 2 hrs. with EtONO, and distilled under reduced pressure to remove EtOH. The residue was made alk. with aqueous KOH and steam-distilled The distillate saturated with NaCl and extracted with Et2O gave 11 g. 2,6-dimethyl-3-fluoropyridine (II), b. 136-8°. A cold solution of 25 g. II in 150 ml. Ac2O was treated with 150 ml. 30% H2O2, left for a few hrs. at room temperature, then kept 30 hrs. at 60° and distilled under reduced pressure to remove AcOH and AcOOH. The whole was dissolved, below 10° in 30 ml. concentrated H2SO4 and 30 ml. 20% oleum, then added carefully to 60 ml. 20% oleum and 90 ml. HNO3 (d. 1.52), kept 1 hr. on a water bath, poured onto 300 g. ice, and neutralized with solid (NH4)2CO3 to give 24 g. I, m. 136° (H2O). I (1 g.) and 30 ml. alc. NH3, saturated at 0°, was autoclaved 4 hrs. at 120-30° and evaporated to dryness. The residue triturated with small amount H2O, cooled, and filtered gave 0.8 g. 2,6-dimethyl-3-amino-4-nitropyridine N-oxide (III), m. 189-90° (H2O). III (0.4 g.), 1 ml. PCl3, in 15 ml. CHCl3 was refluxed 1 hr., evaporated, and the residue neutralized with aqueous KHCO3 to afford 0.3 g. 2,6-dimethyl-3-amino-4-nitropyridine, m. 112° (H2O). III (0.3 g.) reduced in 10 ml. of boiling AcOH with 0.6 g. Fe dust, kept 30 min. on a water bath, made alk. with 50% KOH, and extracted with Et2O gave 0.2 g. 2,6-dimethyl-3,4-diaminopyridine, m. 181° (C6-H6-EtOH); picrate m. 215°. Similarly, reduction of 1 g. I with 2 g. Fe in 25 ml. AcOH afforded 0.7 g. 2,6-dimethyl-3-fluoro-4-aminopyridine, m. 92° (H2O); picrate m. 235° (alc.). Heating of 0.5 g. I and 5 ml. PhNH2 during 2 hrs. at 120-30°, followed by pouring into H2O and acidifying with HCl, yielded 90.3% 2,6-dimethyl-3-phenylamino-4-nitropyridine N-oxide, m. 146° (EtOH-H2O). A solution of 1.5 g. KOH in 13 ml. H2O, treated successively with 2 ml. 30% H2O2 and 1 g. I, kept 30 min. on a water bath, cooled, and filtered, gave 0.8 g. 2,6-dimethyl-8-hydroxy-4-nitropyridine N-oxide, m. 99° (H2O). A mixture of 1 g. I and MeONa, prepared from 0.15 g. metallic Na and 20 ml. MeOH, refluxed 1 hr., evaporated, and extracted with CHCl3, afforded 0.9 g. 2,6-dimethyl-3-methoxy-4-nitropyridine N-oxide, m. 137° (H2OEtOH). Similarly, substitution of F atom in I using EtONa yielded 94.2% 2,6-dimethyl-3-ethoxy-4-nitropyridine N-oxide, m. 103° (aqueous alc.). I (5 g.) refluxed 1 hr. with 10 ml. PCl3 in 10 ml. CHCl3, evaporated, and the residue decomposed with ice and neutralized with Na2CO3 was steam-distilled to give in the distillate 2.5 g. 2,6-dimethyl-3-fluoro-4-chloropyridine, b. 174-5°; picrate m. 125° (alc.). Similarly, I and PBr3 yielded 54.7% 2,6-dimethyl-3-fluoro-4-bromopyridine, m. 67° (ligroine); picrate m. 140° (alc.).
Roczniki Chemii published new progress about 3726-08-7. 3726-08-7 belongs to pyridine-derivatives, auxiliary class Pyridine,Fluoride,Bromide, name is 4-Bromo-3-fluoro-2,6-dimethylpyridine, and the molecular formula is C17H20ClN3, Category: pyridine-derivatives.
Referemce:
https://en.wikipedia.org/wiki/Pyridine,
Pyridine | C5H5N – PubChem