Reactions of the hydrazine derivatives. XXV. Action of acetic anhydride and polyphosphoric acid on acylhydra-zones was written by Sagitullin, R. S.;Kost, A. N.. And the article was included in Vestnik Moskovskogo Universiteta, Seriya Matematiki, Mekhaniki, Astronomii, Fiziki, Khimii in 1959.Recommanded Product: 2,5-Di(pyridin-4-yl)-1,3,4-oxadiazole This article mentions the following:
In the interaction of various acylhydrazones (containing the NH group) with Ac2O, independent of the structure of the acyl residue and the carbonyl components (acetone, cyclohexanone, or benzaldehyde), cyclization took place to yield N-acetyl-oxadiazolines. Under the action of polyphosphoric acid (I) as condensing agent, disproportionation, with the formation of diacylhydrazine and azine, took place; the diacylhydrazine, under the conditions of reaction, separated H2O to give an oxadiazole. Acetone acetylhydrazone (II) (50 g.) and 60 ml. Ac2O was refluxed 45 min., cooled, 100 ml. H2O added, the mixture neutralized with KOH, the oil separated, the aqueous layer extracted twice with Et2O, the combined extracts dried over KOH, the Et2O evaporated, and the residue distilled to yield 70% 2,2,5-trimethyl-3-acetyl-1,3,4-oxadiazoline, b18 88-90°, m. 23-4°, n20D 1.4627, d20 1.0547, MRD 40.75. Cyclohexanone acetylhydrazone, m. 124° (alc.), (2 g.) and 2.5 g. Ac2O was refluxed 1 hr., cooled, 30 ml. H2O added, the mixture neutralized with KOH, and the oil cooled with ice water to yield 51% 5-methyl-2,2-pentamethylene-3-acetyl-1,3,4-oxadiazoline, m. 63-5° (petr. ether). In an analogous manner, 3.5 g. benzaldehyde acetylhydrazone and 7 g. Ac2O was boiled 40 min. to yield 80% 5-methyl-2-phenyl-3-acetyl-1,3,4-oxadiazoline, m. 90-2° (alc.). Acetone benzoylhydrazone (2.5 g.) and 3 g. Ac2O yielded 83% 5,5-dimethyl-2-phenyl-3-acetyl-1,3,4-oxadiazoline, m. 49-50° (petr. ether), λ 292, 305 mμ, log ε 4.176, 4.041. Cyclohexanone benzoylhydrazone (2.5 g.) and 3.3 g. Ac2O yielded (30 min. boiling) 84% 5-phenyl-2,2-pentamethylene-3-acetyl-1,3,4-oxadiazoline, m. 79-80 (petr. ether). Benzaldehyde benzoylhydrazone (15 g.) and 30 g. Ac2O boiled 40 min. yielded 94% 2,5-diphenyl-3-acetyl-1,3,4-oxadiazoline, m. 92-4° (aqueous alc.), λ 290 mμ, log ε 4.16. Cyclohexanone isonicotinoylhydrazone (1 g.) and 2 g. Ac2O yielded 84% 3-acetyl-5-(4-pyridyl)-2,2-pentamethylene-1,3,4-oxadiazoline, m. 104-5°. II (50 g.) and 100 g. I heated 1 hr. at 150-60°, while stirring occasionally the mixture dissolved in 200 ml. H2O, saturated with KOH, the upper oily layer separated, dried thoroughly over KOH, and distilled yielded 82% 3,5,5-trimethylpyrazoline, m. 158-63°; HCl salt m. 168-71°. Acetone benzoylhydrazone (4.5 g.) and 17 g. I was heated 1 hr. at 180-90°, cooled, and poured into cold H2O to yield quant. 2,5-diphenyl-1,3,4-oxadiazole, m. 138-39°, λ 280 mμ, log ε 4.43; traces only of 3,5,5-trimethylpyrazoline were found in the filtrate. In an analogous manner, 15 g. cyclohexanone benzoylhydrazone and 45 g. I boiled 1 hr. at 140-50° yielded 65% 2,5-diphenyl-1,3,4-oxadiazole, m. 137.5-8°; the aqueous solution after the separation of the oxadiazole was neutralized with KOH, extracted with Et2O, the Et2O layer dried over KOH, and Et2O evaporated to yield 1.5 g. cyclohexanone azine, b7 140-3°. Acetone isonicotinoylhydrazone (2.1 g.) and 11 g. I kept 2 hrs. at 170-80° yielded 42% 2,5-di(4-pyridyl)-1,3,4-oxadiazole, m. 185-6° (MeOH). In the experiment, the researchers used many compounds, for example, 2,5-Di(pyridin-4-yl)-1,3,4-oxadiazole (cas: 15420-02-7Recommanded Product: 2,5-Di(pyridin-4-yl)-1,3,4-oxadiazole).
2,5-Di(pyridin-4-yl)-1,3,4-oxadiazole (cas: 15420-02-7) belongs to pyridine derivatives. The pyridine ring occurs in many important compounds, including agrochemicals, pharmaceuticals, and vitamins. Reduced pyridines, namely tetrahydropyridines, dihydropyridines and piperidines, are found in numerous natural and synthetic compounds. The synthesis and reactivity of these compounds have often been driven by the fact many of these compounds have interesting and unique pharmacological properties. Recommanded Product: 2,5-Di(pyridin-4-yl)-1,3,4-oxadiazole