3,6-Dimethyl Pyridazine synthesis

Yield: 56%

Reaction Conditions:

Stage #1:2,5-hexanedione with hydrazine hydrate in ethanol for 3 h;Reflux;
Stage #2: with palladium 10% on activated carbon in ethanol;benzeneReflux;

Steps:

60.A
Step A:
A mixture of hexane-2,5-dione (6 mL, 51 mmol) and hydrazine monohydrate (2.5 mL, 51 mmol) in ethanol (50 mL) was brought to reflux for 3 h, then the solvent was removed under reduced pressure.
The residue was combined with 10% Pd/C (1.1 g) in anhydrous benzene (200 mL).
The reaction mixture was heated at reflux overnight, then cooled to room temperature and filtered through a pad of Celite.
The filtrate was concentrated and purified by silica gel column chromatography (6% MeOH in CH₂Cl₂) to provide 3,6-dimethylpyridazine (3.1 g, 56%) as a light brown oil. ¹H NMR (500 MHz, CDCl₃): δ 7.23 (2H, s), 2.69 (6H, s).

References:

PTC Therapeutics, Inc.;F. Hoffmann-La Roche AG;Woll, Matthew G.;Chen, Guangming;Choi, Soongyu;Dakka, Amal;Huang, Song;Karp, Gary Mitchell;Lee, Chang-Sun;Li, Chunshi;Narasimhan, Jana;Naryshkin, Nikolai;Paushkin, Sergey;Qi, Hongyan;Turpoff, Anthony A.;Weetall, Marla L.;Welch, Ellen;Yang, Tianle;Zhang, Nanjing;Zhang, Xiaoyan;Zhao, Xin;Pinard, Emmanuel;Ratni, Hasane US9617268, 2017, B2 Location in patent:Page/Page column 395; 396