O-Xylene → Phthalazine

1,11′-Carbonyldiimidazole-(0.98 g, 6.1 mmol) was added to a stirred mixture of 3-furoic acid (0.68 g, 6.1 mmol) in THF (30 ml). The mixture was stirred for 0.75 h before adding the preceding hydrazine (1.0 g, 5.1 mmol). After 4 h at room temperature, the solvent was evaporated in vacuo, water added and the mixture stirred for 0.5 h. The resultant solid was collected by filtration, washed with water and hexane and dried in vacuo to give the ketohydrazine. A mixture of the ketohydrazine (0.80 g) and triethylamine hydrochloride (0.10 g, 0.73 mmol) in xylene (10 ml) was heated at reflux overnight. The solution was cooled to room temperature and the solvent removed in vacuo. The residue was chromatographed on silica gel, eluting with 5% methanol/dichloromethane, to give the title-phthalazine (0.21 g), 1H NMR (250 MHz, CDCl3) δ1.90-2.02 (4 H, m, 2 of CH2), 2.74-2.80 (2 H, m, CH2), 3.16-3.24 (2 H, m, CH2), 7.28 (1 H, m, Ar—H), 7.58 (1 H, t, J=1.7 Hz, Ar—H), 8.53 (1 H, m, Ar—H).

1. temperaturewas heated
2. temperatureat reflux overnight
3. customthe solvent removed in vacuo
4. customThe residue was chromatographed on silica gel
5. washeluting with 5% methanol/dichloromethane

ORD record

ord-319007a64c074cc2b67fd129c6ab4380

Source dataset

uspto-grants-2001_07

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06255305B1