2,4,4A,5,6,7-Hexahydro-benzo[6,7]cyclohepta[1,2-C]pyridazin-3-one → 6,7-dihydro-2H-benzo[6,7]cyclohepta[1,2-c]pyridazin-3(5H)-one

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Reaction Steps

A mixture of the compound of formula (Dd), 4a,5,6,7-tetrahydro-2H-benzo[6,7]cyclohepta[c]pyridazin-3(4H)-one (4.7 g, 22 mmol) and anhydrous copper(II) chloride (6 g, 44 mmol) was refluxed in acetonitrile (45 mL) for 2 hours. After cooling to ambient temperature, the mixture was poured into ice-water (200 g) and the solid obtained was washed with 10% HCl solution twice (about 20 mL×2) and cold water twice (about 20 mL×2). After freeze-drying, the compound of formula (De), 3-oxo-6,7-dihydro-5H-benzo[6,7]cyclohepta[1,2-c]pyridazine (4.2 g, 90%) was obtained as a white solid, 1H NMR (300 MHz, CDCl3) δ: 10.80 (bs, 1H), 7.53-7.21 (m, 4H), 6.77 (s, 1H), 2.66 (t, J=6.9 Hz, 2H), 2.45 (t, J=6.9 Hz, 2H), 2.14 (quant, J=6.9 Hz, 2H); LC-MS: purity: 100%; MS (m/e): 213 (MH+).

Provenance & Evidence