Usage And Synthesis
50.0 g of maleic anhydride and 180 ml of methanol are heated for 1 h under
reflux while stirring. The reaction mixture is cooled to room temperature and
the excess methanol is evaporated under reduced pressure. 67.0 g of
monomethyl maleate are obtained. The monomethyl maleate is then cooled to
0°C after which 90 ml of triethylamine and then 34.0 g of isobutylamine are
introduced over a period of 1 h. The reaction mixture is heated under reflux
for 1 h, then cooled to 50°C and 200 ml of acetone added; as a result of
filtering off the crystals which separate there are obtained 73.7 g of methyl Nisobutyl-
β-aspartate, melting point 250°C.
Over a period of 10 min 860 ml of concentrated hydrochloric acid are added to a suspension of 340.0 g of methyl N-isobutyl-β-aspartate in 860 ml of water whilst stirring. The solution is cooled to 0°C and 128.0 g of sodium nitrite dissolved in 280 ml of water are introduced over a period of 1 h 20 min. The reaction mixture is stirred for 2 h at 0°C and extraction is then carried out thrice with a total of 3000 ml of diethyl ether. The organic phase is thrice washed with a total of 1500 ml of water, dried over magnesium sulfate and the ether evaporated under reduced pressure. The residue, when dissolved in a mixture of 1400 ml of petroleum ether and 230 ml of ether, gives, after cooling to 3°C, 325.0 g of methyl N-isobutyl-N-nitroso-β-aspartate, melting point 95°C.
Over a period of 15 min and whilst stirring 158.0 g of methyl N-isobutyl-Nnitroso- β-aspartate are added to 340 ml of acetic anhydride and then, drop by drop, 0.95 ml of 70% perchloric acid. The reaction mixture is then stirred for 2 h at room temperature. The acetic anhydride is evaporated under reduced pressure, and the residue is then successively dissolved once in 100 ml of chloroform, thrice in 100 ml of benzene each time and twice in 100 ml of diethyl ether each time, the solvent being evaporated each time under reduced pressure. 155.0 g of red oil are obtained which are dissolved in 2 volumes of hot di-isopropyl ether and cooled. After 1 min at 3°C the crystals which separate are filtered and there are thus obtained 78.0 g of methyl 3- isobutyl-4-sydnonyl acetate, melting point 39°C.
120.0 g of methyl 3-isobutyl-4-sydnonylacetate and 110.0 g of diphenylacetylene dissolved in 600 ml of xylene are heated under reflux whilst being stirred for 70 h. The solution is cooled to room temperature and the xylene is evaporated under reduced pressure. The residue is dissolved in a mixture of 800 ml of 1 N sodium carbonate and 800 ml of acetone. The resulting solution is heated under reflux for 4 h whilst stirring and is then cooled to room temperature and separated. The aqueous phase has 1000 ml of water added thereto and is then extracted thrice with a total of 900 ml of benzene. The aqueous phase is then made acid by the addition of 68 ml of concentrated hydrochloric acid. The oil which separates from the acidified mixture is extracted using a total of 1000 ml of chloroform in five extractions. The combined chloroform extracts are dried over magnesium sulfate and the chloroform is evaporated under reduced pressure. 78.0 g of a brown oil are obtained which are submitted to chromatography upon silica gel using a mixture of chloroform-methanol 99:1 parts. So the 1-isobutyl-3,4- diphenylpyrazolyl-5-acetic acid, melting point 181°C (recrystallisation from acetonitrile) is obtained.
Over a period of 10 min 860 ml of concentrated hydrochloric acid are added to a suspension of 340.0 g of methyl N-isobutyl-β-aspartate in 860 ml of water whilst stirring. The solution is cooled to 0°C and 128.0 g of sodium nitrite dissolved in 280 ml of water are introduced over a period of 1 h 20 min. The reaction mixture is stirred for 2 h at 0°C and extraction is then carried out thrice with a total of 3000 ml of diethyl ether. The organic phase is thrice washed with a total of 1500 ml of water, dried over magnesium sulfate and the ether evaporated under reduced pressure. The residue, when dissolved in a mixture of 1400 ml of petroleum ether and 230 ml of ether, gives, after cooling to 3°C, 325.0 g of methyl N-isobutyl-N-nitroso-β-aspartate, melting point 95°C.
Over a period of 15 min and whilst stirring 158.0 g of methyl N-isobutyl-Nnitroso- β-aspartate are added to 340 ml of acetic anhydride and then, drop by drop, 0.95 ml of 70% perchloric acid. The reaction mixture is then stirred for 2 h at room temperature. The acetic anhydride is evaporated under reduced pressure, and the residue is then successively dissolved once in 100 ml of chloroform, thrice in 100 ml of benzene each time and twice in 100 ml of diethyl ether each time, the solvent being evaporated each time under reduced pressure. 155.0 g of red oil are obtained which are dissolved in 2 volumes of hot di-isopropyl ether and cooled. After 1 min at 3°C the crystals which separate are filtered and there are thus obtained 78.0 g of methyl 3- isobutyl-4-sydnonyl acetate, melting point 39°C.
120.0 g of methyl 3-isobutyl-4-sydnonylacetate and 110.0 g of diphenylacetylene dissolved in 600 ml of xylene are heated under reflux whilst being stirred for 70 h. The solution is cooled to room temperature and the xylene is evaporated under reduced pressure. The residue is dissolved in a mixture of 800 ml of 1 N sodium carbonate and 800 ml of acetone. The resulting solution is heated under reflux for 4 h whilst stirring and is then cooled to room temperature and separated. The aqueous phase has 1000 ml of water added thereto and is then extracted thrice with a total of 900 ml of benzene. The aqueous phase is then made acid by the addition of 68 ml of concentrated hydrochloric acid. The oil which separates from the acidified mixture is extracted using a total of 1000 ml of chloroform in five extractions. The combined chloroform extracts are dried over magnesium sulfate and the chloroform is evaporated under reduced pressure. 78.0 g of a brown oil are obtained which are submitted to chromatography upon silica gel using a mixture of chloroform-methanol 99:1 parts. So the 1-isobutyl-3,4- diphenylpyrazolyl-5-acetic acid, melting point 181°C (recrystallisation from acetonitrile) is obtained.
Preparation Products And Raw materials
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