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EXAMPLE 1 To the dried barks (50 g) of pine tree(Pinus densiflora Siebold et Zuccarini) was added 1000 ml of aqueous 50% ethanol solution, and the mixture was heated to about 70 C. for 4 hours and filtered. The filtrate was evaporated to give a concentrated extract. Each 500 ml of water and toluene was added to the concentrated extract(roughly 12 g) and a distribution was carried out to give an aqueous layer. A material(roughly 8 g) obtained by evaporating the aqueous layer was subjected to a chromatography on Lichrosorb RP-18 column(3.5*35 cm, Merck) employing as an eluant a mixture of water:acetonitrile:methanol=80:10:10% by weight to give active fractions containing 4-hydroxy-5-methyl-3[2H]-furanone. The active fractions are combined together, evaporated and recrystallized with methanol to give about 0.2 g(yield 0.4%) of 4-hydroxy-5-methyl-3[2H]-furanone.
0.4%
EXAMPLE 2 The dried needles (50 g) of pine tree(Pinus densiflora Siebold et Zuccarini) was immersed in 1000 ml of aqueous 50% acetone solution at room temperature for 7 days and the resulting solution was filtered. The filtrate was evaporated to give a concentrated extract. Each 500 ml of water and cyclohexane was added to the concentrated extract(roughly 14 g) and a distribution was carried out to give an aqueous layer. A material(roughly 10 g) obtained by evaporating the aqueous layer was subjected to a chromatography on Lichrosorb RP-18 column(3.5*35 cm, Merck) employing as an eluant a mixture of water:acetonitrile:methanol=95:2.5:2.5% by weight to give active fractions containing 4-hydroxy-5-methyl-3[2H]-furanone. The active fractions are combined together, evaporated and recrystallized with water to give about 0.2 g(yield 0.4%) of 4-hydroxy-5-methyl-3[2H]-furanone.
0.6%
EXAMPLE 3 The dried barks (50 g) of pine tree(Pinus rigida Mill) was immersed in 1000 ml of aqueous 90% methanol solution at about 70 C. for 4 hours and the resulting solution was filtered. The filtrate was evaporated to give a concentrated extract. Each 500 ml of water and benzene was added to the concentrated extract(roughly 15 g) and a distribution was carried out to give an aqueous layer. A material(roughly 10 g) obtained by evaporating the aqueous layer was subjected to a chromatography on Lichrosorb RP-18 column(3.5*35 cm, Merck) employing as an eluant a mixture of water:acetonitrile:methanol=70:20:10% by weight to give active fractions containing 4-hydroxy-5-methyl-3[2H]-furanone. The active fractions are combined together, evaporated and recrystallized with water to give about 0.3 g(yield 0.6%) of 4-hydroxy-5-methyl-3[2H]-furanone.
0.6%
EXAMPLE 4 The dried needles (50 g) of pine tree(Pinus rigida Mill) was immersed in 1000 ml of aqueous 30% propanol solution at room temperature for 10 days and the resulting solution was filtered. The filtrate was evaporated to give a concentrated extract. Each 500 ml of water and n-hexane was added to the concentrated extract(roughly 13 g) and a distribution was carried out to give an aqueous layer. A material(roughly 11 g) obtained by evaporating the aqueous layer was subjected to a chromatography on Lichrosorb RP-18 column(3.5*35 cm, Merck) employing as an eluant a mixture of water:methanol=70:30% by weight to give active fractions containing 4-hydroxy-5-methyl-3[2H]-furanone. The active fractions are combined together, evaporated and recrystallized with water to give about 0.3 g(yield 0.6%) of 4-hydroxy-5-methyl-3[2H]-furanone.
13 g (57%)
EXAMPLE 3 4-Hydroxy-5-methyl-3-oxo-2H-furan A solution of 37.2 g of 2-carbethoxy-5-methyl-3,4-dihydroxy furan and 32 g of sodium hydroxide in 450 ml of water is kept at room temperature, under nitrogen, for 20 hours. The reaction mixture is acidified (pH3) with concentrated hydrochloric acid, then stirred at 50 C. for 4 hours, and continuously extracted for 6 hours with ether. The ether extract is dried and concentrated under vacuum until the total volume of the solution is reduced to about 50 ml. The ether solution is cooled to -70 C. and filtered. The solid product is washed with pentane and dried, yielding 13 g (57%) of 4-hydroxy-5-methyl-3-oxo-2H-furan, recrystallized from alcohol-ether, m.p. 128.2-129.6 C. NMR (CDCl3), delta 2.26 (3H, t), 4.52 (2H, q), 6.9 (1H, broad).
(c) 1.07 g of the resulting cyanohydrin and 2.0 g of sodium gluconate are refluxed in 15 ml of water for 15 minutes. The mixture is extracted five times with ethyl acetate, the ethyl acetate phases are dried and concentrated, there being obtained 0.42 g of 4-hydroxy-5-methyl-3(2H)-furanone. The recrystallized material (melting point 111-120 C.) shows the following NMR (CDCl3): 7.3 ppm (singlet 1H, OH); 4.5-4.65 ppm (multiplet 3H, CH3).
EXAMPLE 4 4-Hydroxy-5-methyl-3-oxo-2H-furan In a 4 L three-necked flask fitted with a mechanical stirrer, a dropping funnel, a thermometer, a 30 cm Vigreux column connected to a deflegmator and a gas inlet tube, is placed a suspension of 408 g of sodium ethoxide in 3 L of dry toluene. To the stirred suspension is added, under nitrogen, at 0-5 C., 438 g of diethyl oxalate over a period of 75 minutes. To the yellow reaction mixture is then added, at 4-6 C., 612 g of diethyl alpha-methyldiglycolate over a period of 90 minutes. The reaction mixture is stirred at room temperature for an additional 2 hours. The reaction mixture is then warmed up gradually and the ethanol toluene mixture is distilled off till the vapour temperature reaches 107 C. The reaction is then cooled to room temperature and stirred for 30 minutes with 2 L of water. The reaction mixture is transferred to a separatory funnel, the toluene layer is separated off and the water layer is washed with ether. After an addition of 240 g of sodium hydroxide the aqueous layer is kept at room temperature, under nitrogen, for 20 hours. The reaction mixture is acidified (pH3) with concentrated hydrochloric acid, then stirred at 30 C. for 2 hours and continuously extracted for 10 hours with ether. The ether extract is dried and the solvent is removed under vacuum. The solid residue is recrystallized from ethanol yielding 243 g (71%) of 4-hydroxy-5-methyl-3-oxo-2H-furan, m.p. 130-130.5 C.
23
[ 98-01-1 ]
[ 19322-27-1 ]
2-[(2-furyl)methylidene]-4-hydroxy-5-methyl-2H-furan-3-one[ No CAS ]
(c) 3 g of the resulting cyanohydrin are dissolved together with 2.2 g of sodium acetate in 40 ml of water and the solution is heated to 70 C. for 15 minutes. The mixture is then extracted five times with 50 ml of methylene chloride each time. The dried and concentrated methylene chloride phases give 150 mg (6%) of crystalline 4-hydroxy-5-methyl-3(2H)-furanone, which is identical with the product obtained according to Example 2 (c).
34
diethyl α-methyldiglycolate[ No CAS ]
[ 95-92-1 ]
[ 19322-27-1 ]
Yield
Reaction Conditions
Operation in experiment
69 g (60%)
With sodium methylate; In methanol; sodium hydroxide;
EXAMPLE 6 4-Hydroxy-5-methyl-3-oxo-2H-furan In a 2 L three-necked flask fitted with a mechanical stirrer, a dropping funnel, a thermometer and reflux condensor is placed a solution of 108 g of sodium methoxide in 500 ml of methanol. To the stirred solution is added at 0-10 C., 146 g of diethyl oxalate over a period of 30 minutes. To the reaction mixture is then added at 0-10 C. 204 g of diethyl alpha-methyldiglycolate over a period of 120 minutes. The reaction mixture is then stirred at reflux temperature for an additional 13 hours. The solvent is distilled off and the residue is dried at 100 C. under vacuum. The dried residue is dissolved in 600 ml of 15% sodium hydroxide solution. The basic solution is kept at room temperature for 20 hours. The reaction mixture is then acidified and continuously extracted with ether. The ether extract is dried and the solvent is removed under vacuum. The solid residue is recrystallized from alcohol yielding 69 g (60%) of 4-hydroxy-5-methyl-3-oxo-2H-furan, m.p. 130-130.5 C.
EXAMPLE 5 4-Hydroxy-5-methyl-3-oxo-2H-furan Example 4 is repeated substituting dimethyl oxalate for diethyl oxalate and dimethyl alpha-methyldiglycolate for diethyl alpha-methyldiglycolate. There is obtained 253 g (74%) of 4-hydroxy-5-methyl-3-oxo-2H-furan, m.p. 129.5-130 C.