O-Xylene → Phthalazine

Beteiligte Stoffe

Reaktionsschritte

1,1′-Carbonyldiimidazole (1.011 g, 6.23 mmol) was added to a stirred solution of the preceding acid (0.755 g, 5.94 mmol) in DMF (20 ml) at room temperature under nitrogen. The solution was stirred for 1.1 h before adding 3-chloro-6-hydrazino-4,5-diazatricyclo[6.2.2.2.7]dodeca-2(7),3,5-triene (1.335 g, 5.94 mmol). After 2.5 h, the solvent was evaporated in vacuo and the residue triturated with water. The solid was filtered off, washed with water and hexane, and dried in vacuo to give the ketohydrazine (1.645 g, 83%), MS (ES+) m/e 334 [MH]+. A solution of the ketohydrazine (1.855 g, 5.56 mmol) and triethylamine hydrochloride (0.186 g, 0.556 mmol) in xylene (28 ml) was heated at reflux for 3 h. The solution was cooled to room temperature and the solvent evaporated in vacuo. The residue was dissolved in dichloromethane, washed with water (×3), dried (MgSO4) and evaporated in vacuo, and the crude product was chromatographed on silica gel, eluting with 7% methanol/dichloromethane, to give the title-phthalazine (0.917 g, 52%), 1H NMR (250 MHz, CDCl3) δ1.42-1.56 (4H, m, 2 of CH2), 1.92-2.04 (4H, m, 2 of CH2), 2.62 (3H, s, Me), 3.58 (1H, br s, CH), 4.09 (1H, br s, CH), 8.59 (1H, s, Ar—H); MS (ES+) m/e 316 [MH]+.

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