Ethanol → 5-methoxy-2-(tetrahydro-2H-pyran-2-yl)-3(2H)-pyridazinone

Participants

Reaction Conditions

Reaction Steps

4-Chloro-5-methoxy-2-(tetrahydro-2H-pyran-2-yl)-3(2H)-pyridazinone (2486 g, 10.16 moles), ethanol (8 L), triethylamine (2L, 14.23 moles), and 5% Pd-C (100 g of 50% water-wet Pd-C) were added to a 22 L autoclave. The mixture was hydrogenated at 50-60 psi (345-414 kilopascals) of H2 and heated to a maximum temperature of 43° C. After 24 h, the reaction was complete. The reaction mixture was diluted with a small amount of water and vacuum filtered through celite. The filtrate was concentrated and partitioned with 10 L of ethyl acetate and 8 L of H2O. The aqueous phase was extracted with ethyl acetate (2×2 L). The combined organics were washed with 5 L brine, dried (MgSO4), and vacuum filtered. The solution was concentrated in vacuo to give 2133 g (100% yield) of 5-methoxy-2-(tetrahydro-2H-pyran-2-yl)-3(2H)-pyridazinone as a dark oil which later crystallized to give a tan product suitable for further transformations. The product was purified by recrystallization from ethyl acetate/cyclohexane to give a white solid, mp=76°-78° C.

Provenance & Evidence