Originator
Mebron,Daiichi Seiyaku,Japan,1970
Manufacturing Process
A mixture of 16.3 g of 4-methyl-6-methoxy-2-pyrimidinyl-hydrazine,13.7 g of
ethyl acetoacetate and 16.3 ml of methanol was refluxed 2 hours on a water
bath. After a mixture of 4.7 g of sodium hydroxide, 4.7 ml of water and 27 ml
of methanol was added dropwise thereto at about 50°C, the reaction mixture
was refluxed for 2 hours more, then methanol was distilled off and the residue
was dissolved in 130 ml of water. The solution was adjusted to pH 6 with
acetic acid. The precipitate was filtered, washed with water and dried to give
24 g (yield: 95.3%) of crystals, MP 97° to 98°C. Recrystallization from ligroin
gave 1-(4'-methyl-6'-methoxy-2'-pyrimidinyl)-3-methyl-3-pyrazoline-5-one,
MP 102° to 103°C.
To a solution of 4.76 g of 1-( 4'-methyl-6'-methoxy-2'-pyrimidinyl)-3-methyl-
3-pyrazoline 5-one in 200 ml of ether was added an ether solution containing
6 molar equivalents of diazomethane and the reaction mixture was allowed to
stand at room temperature for 20 hours. After distilling off the solvent, the
residue was dissolved in 160 ml of water, made alkaline (pH 10) with sodium
hydroxide solution and extracted three times with 140 ml of benzene. The
extract was washed with a small amount of water, dried over sodium sulfate
and evaporated to give a crystalline mass. Recrystallization from
isopropylether gave 1-(4'-methyl-6'-methoxy-2'-pyrimidinyl)-3-methyl-5-
methoxypyrazole (3.96 g, 84%) as color less prisms, MP 90° to 92°C.
