Bredereck, Hellmut published the artcileRing cleavage of oxazoles with 2,4-dinitrophenylhydrazine, Synthetic Route of 20662-83-3, the publication is Chemische Berichte (1960), 2010-15, database is CAplus.
The ring cleavage of oxazoles with 2,4-(O2N)2C6H3NHNH2 (I) to the osazones of glyoxal derivatives is described. BzCHBrMe (63 g.), 96 g. HCO2NH4, 390 g. HOC2H, and 45 cc. Ac2O refluxed 5 hrs. and distilled gave 24 g. 5-methyl-4-phenyloxazole (II), b11 122°, m. 1°, n20D 1.5723. BzCH(OH)Ph (53 g.), 225 g. HCONH2, and 49 g. concentrated H2SO4 heated 1 hr. at 100-20° and 2 hrs. at 150° yielded 33.5 g. 4,5-diphenyloxazole (IIa), b0.002 115°, m. 44°. BzCH2Br (100 g.) and 50 g. AcNH2 heated 2 hrs. at 120-40° gave 35 g. 2-methyl-4-phenyloxazole (III), b11 116°, m. 42.5°. The appropriate oxazole (about 1 g.) in 10 cc. MeOH and 600 cc. reagent solution (cold-saturated solution of I in 2N HCl) kept at room temperature and filtered, and the residue washed with 2N HCl and H2O, dried, and recrystallized from HCONMe2 gave the corresponding cleavage product. III gave (during 2 weeks) phenylglyoxal 2,4-dinitrophenylosazone (IV), m. 299-300°, and benzoylcarbinol 2,4-dinitrophenylosazone (V), m. 234-5°. 4-Phenyloxazole (VI) gave (during 6 weeks) IV and V. 2-Methyl-4-carbethoxyoxazole (VII) gave (during 2 days) Et α-acetamido-α-formylacetate 2,4-dinitrophenylhydrazone (VIII), m. 185-6° (EtOAc), and (during 12 days) VIII and [2,4-(O2N)2C6H3NHN: CH]2 (IX), m. 328-30°. The appropriate oxazole (about 1 g.) refluxed with 400 cc. reagent solution (1% I in 2N HCl) and worked up in the usual manner gave the derivative of the cleavage product(s) in 75-95% yield. IIa gave [2,4-(O2N)2C6H3NHN:CPh]2, m. 310-11° (decomposition), which was also obtained by refluxing 2 g. Bz2, 5 g. I, and 400 cc. 6N HCl 10 hrs., and boiling the precipitate with 300 cc. EtOAc and recrystallizing it from HCONMe2. 4,5-Dimethyloxazole, b760 128°, n20D 1.4281, and 2,4,5-trimethyloxazole, b11 43°, n20D 1.4270, yielded similarly [2,4-(O2N)2C6H3NHN:-CMe]2, m. 330-3° (decomposition). II, 5-methyl-4-phenyloxazole, and 2,5-dimethyl-4-phenyloxazole gave methylphenylglyoxal 2,4-dinitrophenylosazone, m. 259°. VII gave IX, m. 328-30° (decomposition). III and VI yielded IV, m. 299-300°. 5-Ethyl-4-phenyloxazole and 2-methyl-5-ethyl-4-phenyloxazole yielded ethylphenylglyoxal 2,4-dinitrophenylosazone, m. 226°. 5-Propyl-4-phenyloxazole gave propylphenylglyoxal 2,4-dinitrophenylosazone, m. 244°. 4-Methyl-5-benzyl-, 2,4-dimethyl-5-benzyl-, and 2,5-dimethyl-4-benzyloxazole yielded methylbenzylglyoxal 2,4-dinitrophenylosazone, m. 264°. 4,5-Diethyloxazole, 2-methyl-4,5-diethyloxazole, b30 76°, n20D 1.4423, and 2,4,5-triethyloxazole, b30 85°, n20D 1.4494, gave [2,4-(O2N)2C6H3NHN:CEt]2, m. 290-1°.
Chemische Berichte published new progress about 20662-83-3. 20662-83-3 belongs to oxazolidine, auxiliary class Oxazole, name is 4,5-Dimethyloxazole, and the molecular formula is C5H7NO, Synthetic Route of 20662-83-3.
Referemce:
https://en.wikipedia.org/wiki/Oxazolidine,
Oxazolidine | C3H7NO – PubChem