Hydrazine hydrate (1:1) → 2,4,4A,5,6,7-Hexahydro-benzo[6,7]cyclohepta[1,2-C]pyridazin-3-one

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Reaction Steps

A mixture of the compound of formula (Dc), 2-(5-oxo-6,7,8,9-tetrahydro-5H-benzo[7]annulen-6-yl)acetic acid, (5.7 g, 26.1 mmol) and hydrazine hydrate (1.6 mL, 32.7 mmol) in 20 mL of ethanol was refluxed for 2 h, cooled and filtered (washed with small amount of EtOH) to give the compound of formula (Dd), 4a,5,6,7-tetrahydro-2H-benzo[6,7]cyclohepta[c]pyridazin-3(4H)-one, as a white solid (4.7 g, 84%); 1H NMR (300 MHz, CDCl3) δ: 8.61 (bs, 1H), 7.53-7.14 (m, 4H), 2.98-2.75 (m, 3H), 2.58 (dd, J=15.3, 16.8 Hz, 1H), 2.31 (dd, J=12.0, 16.8 Hz, 1H), 1.96-1.59 (m, 4H); LC-MS: purity: 100%; MS (m/e): 215 (MH+).

Provenance & Evidence