ethyl 4,4-diethoxy-3-oxobutanoate

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

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

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

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

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: To a mixture of ethyl 4,4-diethoxy-3-oxobutanoate (prepared according to the method of E. Graf, R. Troschutz, Synthesis, 1999, 7, 1216; 10.0 g, 46 mmol) and cyclopropane-carboximidamide monohydrochloride (Lancaster Synthesis, 5.0 g, 41 mmol) in methanol (100 mL) was added a methanol solution of sodium methoxide (5.4 M, 8.4 mL, 46 mmol). The reaction mixture was stirred overnight. The solvent was removed with a rotary evaporator. Dichloromethane was added and the mixture was filtered. The solvent from the filtrate was removed with a rotary evaporator. The residue was purified by medium pressure liquid chromatography (MPLC) (35→100% ethyl acetate in hexanes as eluant) to afford the title compound as a white solid (4.67 g). prepared Troschutz, Synthesis, 1999, 7, 1216 The solvent was removed with a rotary evaporator Dichloromethane was added the mixture was filtered The solvent from the filtrate was removed with a rotary evaporator The residue was purified by medium pressure liquid chromatography (MPLC) (35→100% ethyl acetate in hexanes as eluant)

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

Procedure: To a mixture of ethyl 4,4-diethoxy-3-oxobutanoate (prepared according to the method of E. Graf, R. Troschutz, Synthesis, 1999, 7, 1216; 10.0 g, 46 mmol) and cyclopropane-carboximidamide monohydrochloride (Lancaster Synthesis, 5.0 g, 41 mmol) in methanol (100 mL) was added a methanol solution of sodium methoxide (5.4 M, 8.4 mL, 46 mmol). The reaction mixture was stirred overnight. The solvent was removed with a rotary evaporator. Dichloromethane was added and the mixture was filtered. The solvent from the filtrate was removed with a rotary evaporator. The residue was purified by medium pressure liquid chromatography (MPLC) (35→100% ethyl acetate in hexanes as eluant) to afford the title compound as a white solid (4.67 g). prepared Troschutz, Synthesis, 1999, 7, 1216 The solvent was removed with a rotary evaporator Dichloromethane was added the mixture was filtered The solvent from the filtrate was removed with a rotary evaporator The residue was purified by medium pressure liquid chromatography (MPLC) (35→100% ethyl acetate in hexanes as eluant)

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

Procedure: A portion (˜40.4 mL) of the ethanol solution of cyclopropanecarboximidamide monohydrochloride as prepared in Example 1 was added to a portion (˜210 mL) of the solution of the sodium salt of ethyl 4,4-diethoxy-3-oxobutanoate as prepared in Example 2. The mixture was allowed to stir overnight at room temperature. The mixture was boiled for about 2 h and then allowed to cool to room temperature. The mixture was evaporated under reduced pressure, and the residue was redissolved in toluene (200 mL). A solution of ammonium chloride (0.68 g, 12.7 mmol) in water (30 mL) was added. After stirring for 10 minutes, the aqueous phase was removed. The organic phase was dried and evaporated to leave the product as pale yellow solid (27.27 g, 88% yield). Product recrystallized from hexanes melted at 111.5-112.0° C. as prepared in Example 2 The mixture was boiled for about 2 h to cool to room temperature The mixture was evaporated under reduced pressure the residue was redissolved in toluene (200 mL) After stirring for 10 minutes the aqueous phase was removed The organic phase was dried evaporated

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

Procedure: A portion (˜40.4 mL) of the ethanol solution of cyclopropanecarboximidamide monohydrochloride as prepared in Example 1 was added to a portion (˜210 mL) of the solution of the sodium salt of ethyl 4,4-diethoxy-3-oxobutanoate as prepared in Example 2. The mixture was allowed to stir overnight at room temperature. The mixture was boiled for about 2 h and then allowed to cool to room temperature. The mixture was evaporated under reduced pressure, and the residue was redissolved in toluene (200 mL). A solution of ammonium chloride (0.68 g, 12.7 mmol) in water (30 mL) was added. After stirring for 10 minutes, the aqueous phase was removed. The organic phase was dried and evaporated to leave the product as pale yellow solid (27.27 g, 88% yield). Product recrystallized from hexanes melted at 111.5-112.0° C. as prepared in Example 2 The mixture was boiled for about 2 h to cool to room temperature The mixture was evaporated under reduced pressure the residue was redissolved in toluene (200 mL) After stirring for 10 minutes the aqueous phase was removed The organic phase was dried evaporated

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

Procedure: 2-(i) To a mixture of methyl 2-formylbenzoate (4.92 g), ethyl 4,4-diethoxyacetoacetate (7.2 g) and acetic acid (0.36 g) in benzene (15 ml) was added portionwise each one third portion of a solution of piperidone (306 mg) in benzene (5 ml) for each 20 minutes' interval, and the mixture was heated to reflux for 3 hours under removing off azeotropically the resulting water. After cooling, the reaction mixture was diluted with additional benzene (25 ml), washed three times with water and successively with diluted aqueous sodium bicarbonate solution, water and saturated aqueous sodium chloride solution and dried over magnesium sulfate. The solvent was distilled off under reduced pressure to give reddish oil (12.7 g) of crude ethyl 2-(2-methoxycarbonylbenzyliden)-4,4-diethoxyacetoacetate which was used in the following reaction without any further purification. the mixture was heated to reflux for 3 hours under removing off azeotropically the resulting water After cooling the reaction mixture was diluted with additional benzene (25 ml) washed three times with water successively with diluted aqueous sodium bicarbonate solution, water and saturated aqueous sodium chloride solution and dried over magnesium sulfate The solvent was distilled off under reduced pressure

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

Procedure: A solution of thiophene-2-carbaldehyde (2.2430 g), ethyl 4,4-diethoxyacetoacetate (4.3648 g) and piperidine (4 drops) in benzene (20 ml) was refluxed under azeotropic dehydration for 4.5 hours. After cooling, to the resultant solution was added diethyl ether, and the solution was washed with water and dried. The solvent was removed from the reaction mixture to give oily ethyl 2-(2-thenylidene)-4,4-diethoxyacetoacetate. The mixture of the compound obtained above and ethyl 3-aminocrotonate (2.6 g) was heated in an oil bath (about 100° C.) for 7.5 hours. The resultant mixture was dissolved in diethyl ether, washed with water and dried. The solvent was removed to give brown oil (9.0 g). The oil was purified by column chromatography on silica gel with an eluent (benzene:ethyl acetate=20:1) to give diethyl 2-methyl-4-(2-thienyl)-6-diethoxymethyl-1,4-dihydropyridine-3,5-dicarboxylate. The product was recrystallized from n-hexane to give yellowish crystals (2.2056 g), m.p. 77° to 77.5° C. the solution was washed with water dried The solvent was removed from the reaction mixture