butane-2,3-dione

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:25.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A mixture of 0,5 g (2,6 mmol) 5,6-diamino-2,3-dihydroxyquinoxaline and 10 ml water was at 50° C. added a solution of 0,45 g (5,2 mmol) 2,3-butanedione in 5 ml water. The reaction mixture was stirred at 50° for 4 h. After cooling to 25° C., the precipitate was filtered off and washed with water. The crude product was dissolved in 2N sodium hydroxide and reprecipitated with 2N hydrochloric acid to pH 6-7 to give 0,4 g (64%) 2,3-dihydroxy-8,9-dimethylpyrazino(2,3-f)quinoxaline, m.p.>300° C. NMR (DMSO-d6): 7.27 (1H,d), 6.93 (1H,d), 2.07 (6H,s). was at 50° C. the precipitate was filtered off washed with water The crude product was dissolved in 2N sodium hydroxide reprecipitated with 2N hydrochloric acid to pH 6-7

Conditions: temp:50.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A mixture of 0,5 g (2,24 mmol) 5,6-diamino-7-chloro-2,3-dihydroxyquinoxaline in 10 ml water was at 50° C. added a solution of 0,4 g (4,6 mmol) 2,3-butanedione in 5 ml water. The reaction mixture was stirred at 50° C. for 24 h. After cooling to 25° C., the precipitate was filtered off and washed with water and ethanol to give 0,3 g (50%) 6-chloro-2,3- dihydroxy-8,9-dimethylpyrazino(2,3-f)quinoxaline, m.p.>300° C. NMR (DMSO-d6) 8.47 (1H,s), 2.60 (3H,s), 2.53 (3H,s). was at 50° C. After cooling to 25° C. the precipitate was filtered off washed with water and ethanol

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A mixture of 6-chloropyrimidine-4,5-diamine (1.4 g, 10 mmol) and 2,3-butanedione (2.0 g, 23 mmol) in toluene (35 mL) and methanol (10 mL) was stirred at reflux for 1 h. Upon cooling, the product precipitated and was collected by suction filtration and rinsed with a MeOH/Et2O mixture (ca. 1:2), then air dried to afford 6,7-dimethylpteridin-4-ol (1.4 g, 72%) as a gold powder. at reflux for 1 h Upon cooling the product precipitated was collected by suction filtration rinsed with a MeOH/Et2O mixture (ca. 1:2) air dried

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Using Method A above, (Z)-4,5-diamino-1,3-dihydro-3-[(3-methoxy-1H-pyrrol-2-yl)methylene]-2H-indol-2-one (60 mg, 0.22 mmol) (Starting Material 5) was condensed with 2,3-butanedione (135 μL) (Aldrich) in ethanol (3 ml) at reflux to give (Z)-7,9-dihydro-2,3-dimethyl-9-[(3-methoxy-1H-pyrrol-2-yl)methylene]-8H-pyrrolo-[3,2-f]quinoxalin-8-one in 100% yield. at reflux

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: The reaction of ethyl 2-methylundecanoate (11.4 g, 0.05 mole) with 2,3-butanedione (4.73 g, 0.055 mole) is conducted in the manner described in Example I, and 16.6 g of a crude oil is obtained. The crude oil product is subjected to high pressure liquid chromatography on silica gel using 5% ethyl acetate in hexane as the eluant, yielding a pure product (9.2 g, 59%), b.p. 100° C. (Kugelrohr air bath temperature) at 0.01 mm Hg. 16.6 g of a crude oil is obtained

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: The reaction of ethyl 2-methylundecanoate (11.4 g, 0.05 mole) with 2,3-butanedione (4.73 g, 0.055 mole) is conducted in the manner described in Example I, and 16.6 g of a crude oil is obtained. The crude oil product is subjected to high pressure liquid chromatography on silica gel using 5% ethyl acetate in hexane as the eluant, yielding a pure product (9.2 g, 59%), b.p. 100° C. (Kugelrohr air bath temperature) at 0.01 mm Hg. 16.6 g of a crude oil is obtained

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: The Grignard reagent (6.13 moles) was added to 480 g of 2,3-butanedione dissolved in 1.95 L of THF and 3.25 L of PhMe while maintaining the temperature at -6° C.±4° C. After the reaction was complete, it was quenched with 5% sulfuric acid to pH=4.5±1, then worked up as in Example I to give 689 g of crude product. Vacuum distillation (88°-93° C., 1.2-3 mm Hg) gave 3-hydroxy-3-phenylbutan-2-one in 56.6% yield. it was quenched with 5% sulfuric acid to pH=4.5±1 to give 689 g of crude product Vacuum distillation (88°-93° C., 1.2-3 mm Hg)

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: The Grignard reagent (6.13 moles) was added to 480 g of 2,3-butanedione dissolved in 1.95 L of THF and 3.25 L of PhMe while maintaining the temperature at -6° C.±4° C. After the reaction was complete, it was quenched with 5% sulfuric acid to pH=4.5±1, then worked up as in Example I to give 689 g of crude product. Vacuum distillation (88°-93° C., 1.2-3 mm Hg) gave 3-hydroxy-3-phenylbutan-2-one in 56.6% yield. it was quenched with 5% sulfuric acid to pH=4.5±1 to give 689 g of crude product Vacuum distillation (88°-93° C., 1.2-3 mm Hg)

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: The process can also be run in mixtures of tetrahydrofuran and toluene, thereby making the process more economical. When 1.1 equivalent of phenylmagnesium bromide (1.9M in 50% THF/PhMe) was added to 2,3-butanedione in 50% THF/PhMe, crude product was isolated in 82.4% yield (Run 10, Table IV) after work-up. Short path vacuum distillation gave 3-hydroxy-3-phenylbutan-2-one in 68% yield. Alternatively, preparation of phenylmagnesium bromide in 38% THF/PhMe, followed by reaction with 2,3-butanedione in 38% THF/PhMe afforded 3-hydroxy-3-phenylbutan-2-one in 66.4% yield (Run 11, Table IV) after work-up and distillation. Similarly phenylmagnessium bromide in 25% THR/PheMe reacted with 2,3-butanedione in 25% THF/PheMe yielded 3-hydroxy-3-phenylbutan-2-one in 56.9% yield after work-up and distillation.

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: The process can also be run in mixtures of tetrahydrofuran and toluene, thereby making the process more economical. When 1.1 equivalent of phenylmagnesium bromide (1.9M in 50% THF/PhMe) was added to 2,3-butanedione in 50% THF/PhMe, crude product was isolated in 82.4% yield (Run 10, Table IV) after work-up. Short path vacuum distillation gave 3-hydroxy-3-phenylbutan-2-one in 68% yield. Alternatively, preparation of phenylmagnesium bromide in 38% THF/PhMe, followed by reaction with 2,3-butanedione in 38% THF/PhMe afforded 3-hydroxy-3-phenylbutan-2-one in 66.4% yield (Run 11, Table IV) after work-up and distillation. Similarly phenylmagnessium bromide in 25% THR/PheMe reacted with 2,3-butanedione in 25% THF/PheMe yielded 3-hydroxy-3-phenylbutan-2-one in 56.9% yield after work-up and distillation.

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: The process can also be run in mixtures of tetrahydrofuran and toluene, thereby making the process more economical. When 1.1 equivalent of phenylmagnesium bromide (1.9M in 50% THF/PhMe) was added to 2,3-butanedione in 50% THF/PhMe, crude product was isolated in 82.4% yield (Run 10, Table IV) after work-up. Short path vacuum distillation gave 3-hydroxy-3-phenylbutan-2-one in 68% yield. Alternatively, preparation of phenylmagnesium bromide in 38% THF/PhMe, followed by reaction with 2,3-butanedione in 38% THF/PhMe afforded 3-hydroxy-3-phenylbutan-2-one in 66.4% yield (Run 11, Table IV) after work-up and distillation. Similarly phenylmagnessium bromide in 25% THR/PheMe reacted with 2,3-butanedione in 25% THF/PheMe yielded 3-hydroxy-3-phenylbutan-2-one in 56.9% yield after work-up and distillation. crude product was isolated in 82.4% yield (Run 10, Table IV) after work-up Short path vacuum distillation