Hydrazine hydrate (1:1) → 4-Methyl-6-phenyl-4,5-dihydropyridazin-3(2H)-one

Participants

Reaction Steps

(Hansen, K B et al. Org. Process Res. Dev., 2005, 9, 634-639, Nelson, D A. US 20050137397A1). A 250 ml three-neck round bottom flask fit with a temperature probe and condenser was charged with 7.7 g (40 mmol) of 2-methyl-4-oxo-4-phenylbutanoic acid 12 and 20 ml of ethanol (95%). The suspension was cooled to below 10° C. and 2.2 ml (42 mmol, 1.05 equiv) of hydrazine monohydrate in 10 ml of ethanol was added dropwise. After addition, the reaction mixture was heated to reflux and stirred for 2 h. The reaction mixture was cooled to ambient temperature and forming white crystals were collected by filtration. The solid was then washed with 2N NaHCO3 (1×30 mL), Milli-Q water (3×60 mL) and dried over a medium frit sintered glass funnel in vacuo to give the desired product 13 in 96.1% yield. 1H NMR, (DMSO-d6): δ 10.84 (s, 1H), 7.75 (m, 2H), 7.41 (m, 3H), 3.12 (m, 1H), 2.60 (m, 1H), 2.50 (m, 1H), 1.13 (d, J=7 Hz, 3H). HPLC (tr/purity): PENDING min, >95%; ESI (MeOH) 189.08 (MH+)

Provenance & Evidence