dimethyl 2-bromopropanedioate

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

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

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

Procedure: By following the procedure of D. T. Warner, cited above, used for preparing diethyl 2-formylcyclopropane-1,1-dicarboxylate from acrolein but using equivalent amount of dimethylbromomalonate and methanol instead of diethylbromomalonate and ethanol, respectively, the title compound, nmr (CDCl3) δ 1.98 (m,2H), 2.80(m, 1H), 3.79(s,6H), 8.82(d, J = 4 cps, 1H), is obtained.

Conditions: temp:0.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Dimethyl bromomalonate (6.6 ml.) was added to a stirred solution of L-alanyl-L-proline t-butyl ester (22.9 g.) in dichloromethane (40 ml.) which was cooled to 0° C., and the mixture was allowed to warm up to laboratory temperature and stirred at that temperature for 16 hours, then diluted with dichloromethane (150 ml.). The solution was washed successively twice with aqueous 0.5N-citric acid solution (150 ml. each time), water (200 ml.) and saturated aqueous sodium chloride solution (200 ml.), dried over magnesium sulphate and evaporated to dryness. The residue was purified by chromatography on a silica gel column using a 4:1 v/v mixture of dichloromethane and ethyl acetate as eluant, and there was thus obtained as an oil N-(dimethoxycarbonylmethyl)-L-alanyl-L-proline t-butyl ester. to warm up to laboratory temperature The solution was washed successively twice with aqueous 0.5N-citric acid solution (150 ml each time), water (200 ml.) and saturated aqueous sodium chloride solution (200 ml.), dried over magnesium sulphate evaporated to dryness The residue was purified by chromatography on a silica gel column a 4:1 v/v mixture of dichloromethane and ethyl acetate as eluant

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

Procedure: By following the procedure of D. T. Warner, cited above, used for preparing diethyl 2-formylcyclopropane-1,1-dicarboxylate from acrolein but using equivalent amount of dimethylbromomalonate and methanol instead of diethylbromomalonate and ethanol, respectively, the title compound, nmr (CDCl3) δ1.98 (m,2H), 2.80(m, 1H), 3.79(s,6H), 8.82(d, J = 4 cps, 1H), is obtained.

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

Procedure: By following the procedure of D. T. Warner, cited above, used for preparing diethyl 2-formylcyclopropane-1,1-dicarboxylate from acrolein but using equivalent amount of dimethylbromomalonate and methanol instead of diethylbromomalonate and ethanol, respectively, the title compound, nmr (CDCl3) δ1.98 (m,2H), 2.80(m, 1H), 3.79(s,6H), 8.82(d, J = 4 cps, 1H), is obtained.

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

Procedure: A stirring suspension of 5-methylsalicylaldehyde (1.0 mg, 7.5 mmol), K2CO3 (1.55 g, 11.0 mmol), and Bu4NBr (322 mg, 1 mmol) in toluene (30 ml) was treated with dimethylbromomalo-nate (1.06 ml, 8.0 mmol). The suspension was heated to reflux with a Dean-Stark trap for 20 h. The brown suspension was cooled to 25° C. and concentrated in vacuo. The residue was taken in DCM and filtered. The filtrate was washed with H2O, 1N NaOH and brine. The organic layer was dried over magnesium sulfate, filtered and concentrated. The crude residue was purified by column chromatography (10% ethyl acetate/hexane) to afford the title compound 583 (600 mg, 42% yield). LRMS: 190.2 (Calc.); 191.1 (found). The suspension was heated to reflux with a Dean-Stark trap for 20 h concentrated in vacuo filtered The filtrate was washed with H2O, 1N NaOH and brine The organic layer was dried over magnesium sulfate filtered concentrated The crude residue was purified by column chromatography (10% ethyl acetate/hexane)

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

Procedure: A stirring suspension of 5-methylsalicylaldehyde (1.0 mg, 7.5 mmol), K2CO3 (1.55 g, 11.0 mmol), and Bu4NBr (322 mg, 1 mmol) in toluene (30 ml) was treated with dimethylbromomalo-nate (1.06 ml, 8.0 mmol). The suspension was heated to reflux with a Dean-Stark trap for 20 h. The brown suspension was cooled to 25° C. and concentrated in vacuo. The residue was taken in DCM and filtered. The filtrate was washed with H2O, 1N NaOH and brine. The organic layer was dried over magnesium sulfate, filtered and concentrated. The crude residue was purified by column chromatography (10% ethyl acetate/hexane) to afford the title compound 583 (600 mg, 42% yield). LRMS: 190.2 (Calc.); 191.1 (found). The suspension was heated to reflux with a Dean-Stark trap for 20 h concentrated in vacuo filtered The filtrate was washed with H2O, 1N NaOH and brine The organic layer was dried over magnesium sulfate filtered concentrated The crude residue was purified by column chromatography (10% ethyl acetate/hexane)

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

Procedure: By following the procedure of D. T. Warner, cited above, used for preparing diethyl 2-formylcyclopropane-1,1-dicarboxylate from acrolein but using equivalent amounts of dimethylbromomalonate and methanol instead of diethylbromomalonate and ethanol, respectively, the title compound, nmr (CDCl3) δ 1.98 (m, 2H), 2.80 (m, 1H), 3.79 (s, 6H), 8.82 (d, J = 4 cps, 1H), is obtained.

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

Procedure: By following the procedure of D. T. Warner, cited above, used for preparing diethyl 2-formylcyclopropane-1,1-dicarboxylate from acrolein but using equivalent amounts of dimethylbromomalonate and methanol instead of diethylbromomalonate and ethanol, respectively, the title compound, nmr (CDCl3) δ 1.98 (m, 2H), 2.80 (m, 1H), 3.79 (s, 6H), 8.82 (d, J = 4 cps, 1H), is obtained.

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

Procedure: To a solution of 2-(3,5-dibromo-4-methoxybenzoyl)-4,5-dimethoxy-benzoic acid (6.30 g) in dimethylformamide (50 ml) are added potassium carbonate (4.04 g) and dimethyl bromomalonate (3.43 g), and the mixture is stirred at room temperature overnight. To the reaction mixture are added ethyl acetate and water. The ethyl acetate layer is separated, washed, dried, and concentrated under reduced pressure. To the residue are added dioxane (30 ml) and conc. hydrochloric acid (30 ml), and the mixture is heated under reflux for five hours. The reaction mixture is cooled, and thereto are added ethyl acetate and water. The ethyl acetate layer is separated, and washed. The remaining aqueous layer is acidified with 10% hydrochloric acid, and then extracted with ethyl acetate. The extract is washed, and dried. The extracts are combined, and concentrated under reduced pressure. The residue is crystallized from ether to give 4(3,5-dibromo-4-methoxyphenyl)-6,7-diethoxy-isocoumarin-3-carboxylic acid (1.32 g) as listed in Table 58. The ethyl acetate layer is separated washed dried concentrated under reduced pressure To the residue are added dioxane (30 ml) and conc. hydrochloric acid (30 ml) the mixture is heated under reflux for five hours The reaction mixture is cooled are added ethyl acetate and water The ethyl acetate layer is separated washed extracted with ethyl acetate The extract is washed dried concentrated under reduced pressure The residue is crystallized from ether

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

Procedure: To a solution of 2-(3,5-dibromo-4-methoxybenzoyl)-4,5-dimethoxy-benzoic acid (6.30 g) in dimethylformamide (50 ml) are added potassium carbonate (4.04 g) and dimethyl bromomalonate (3.43 g), and the mixture is stirred at room temperature overnight. To the reaction mixture are added ethyl acetate and water. The ethyl acetate layer is separated, washed, dried, and concentrated under reduced pressure. To the residue are added dioxane (30 ml) and conc. hydrochloric acid (30 ml), and the mixture is heated under reflux for five hours. The reaction mixture is cooled, and thereto are added ethyl acetate and water. The ethyl acetate layer is separated, and washed. The remaining aqueous layer is acidified with 10% hydrochloric acid, and then extracted with ethyl acetate. The extract is washed, and dried. The extracts are combined, and concentrated under reduced pressure. The residue is crystallized from ether to give 4(3,5-dibromo-4-methoxyphenyl)-6,7-diethoxy-isocoumarin-3-carboxylic acid (1.32 g) as listed in Table 58. The ethyl acetate layer is separated washed dried concentrated under reduced pressure To the residue are added dioxane (30 ml) and conc. hydrochloric acid (30 ml) the mixture is heated under reflux for five hours The reaction mixture is cooled are added ethyl acetate and water The ethyl acetate layer is separated washed extracted with ethyl acetate The extract is washed dried concentrated under reduced pressure The residue is crystallized from ether