ethyl 2-oxobutanoate

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

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

Procedure: The p-chlorophenylhydrazone of ethyl 2-oxobutanoate was prepared by adaptation of the Japp-Klingemann reaction as described by lions and Hughes (J. Proc. Roy. Soc. N. S. Wales 1939, 71: 445) to p-chloroaniline and ethyl 2-ethylacetoacetate. This phenylhydrazone was treated with HCl-ethanol according to the procedure of lions and Hughes (J. Proc. Roy. Soc. N. S. Wales 1939, 71: 445) as applied therein to the corresponding bromophenylhydrazone. The title substance was collected by filtration as an orange solid after suspending the concentrated residue in water. The title substance was collected by filtration as an orange solid

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

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

Procedure: The 2-oxo-butyric acid ethyl ester prepared above was dissolved in chloroform (100 mL) and bromine (20.964 g, 131.19 mmol) was added dropwise at room temperature. The reaction mixture was allowed to stir for 18 h. Concentration of the reaction mixture under reduced pressure provided 12.0 g of the title compound as an orange oil. 1H NMR (CDCl3) δ 4.39 (q, 2H), 4.32 (q, 1H), 1.88 (d, 3H), 1.39 (t, 3H).

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

Procedure: 2-Oxo-butyric acid (10.0 g, 97.2 mmol) was dissolved in ethanol (100 mL) and p-toluene sulfonic acid mono hydrate (0.1 g) was added. The reaction mixture was heated to reflux for 48 h. After cooling the reaction mixture to room temperature, the ethanol was removed under reduced pressure to give 11.4 g of 2-oxo-butyric acid ethyl ester. The reaction mixture was heated to reflux for 48 h the ethanol was removed under reduced pressure

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

Procedure: 2-Oxo-butyric acid (10.0 g, 97.2 mmol) was dissolved in ethanol (100 mL) and p-toluene sulfonic acid mono hydrate (0.1 g) was added. The reaction mixture was heated to reflux for 48 h. After cooling the reaction mixture to room temperature, the ethanol was removed under reduced pressure to give 11.4 g of 2-oxo-butyric acid ethyl ester. The reaction mixture was heated to reflux for 48 h the ethanol was removed under reduced pressure

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

Procedure: The p-chlorophenylhydrazone of ethyl 2-oxobutanoate was prepared by adaptation of the Japp-Klingemann reaction as described by Lions and Hughes (J. Proc. Roy. Soc. N.S. Wales 1939, 71: 445) to p-chloroaniline and ethyl 2-ethylacetoacetate. This phenylhydrazone was treated with HCl-ethanol according to the procedure of Lions and Hughes (J. Proc. Roy. Soc. N.S. Wales 1939, 71: 445) as applied therein to the corresponding bromophenylhydrazone. The title substance was collected by filtration as an orange solid after suspending the concentrated residue in water. The title substance was collected by filtration as an orange solid

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

Procedure: The 2-oxo-butyric acid ethyl ester prepared above was dissolved in chloroform (100 mL) and bromine (20.964 g, 131.19 mmol) was added dropwise at room temperature. The reaction mixture was allowed to stir for 18 h. Concentration of the reaction mixture under reduced pressure provided 12.0 g of the title compound as an orange oil. 1H NMR (CDCl3) δ 4.39 (q, 2H), 4.32 (q, 1H), 1.88 (d, 3H), 1.39 (t, 3H).

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

Procedure: 2-Oxo-butyric acid (10.0 g, 97.2 mmol) was dissolved in ethanol (100 mL) and p-toluene sulfonic acid mono hydrate (0.1 g) was added. The reaction mixture was heated to reflux for 48 h. After cooling the reaction mixture to room temperature, the ethanol was removed under reduced pressure to give 11.4 g of 2-oxo-butyric acid ethyl ester. The reaction mixture was heated to reflux for 48 h the ethanol was removed under reduced pressure

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

Procedure: A reaction mixture consisting of 11 g. (0.085 mole) ethyl 2-oxobutyrate, 17 g. (0.077 mole) (2,4,6-trichlorophenyl)hydrazine, and 200 ml. benzene was heated at the reflux temperature with a Dean and Stark water trap attached to the reaction vessel. When all the water produced by the reaction had been removed, the benzene was removed by evaporation under reduced pressure. The oily residue that remained was dissolved in hot technical hexane, and this solution was allowed to cool. Crystals of the desired product separated and 15.2 g. were recovered. Recrystallization from methanol gave an analytical sample of ethyl 2-oxobutyrate 2-(2,4,6-trichlorophenyl)hydrazone having a melting point at 97° to 99° C. had been removed the benzene was removed by evaporation under reduced pressure The oily residue that remained was dissolved in hot technical hexane to cool Crystals of the desired product separated were recovered Recrystallization from methanol

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

Procedure: The p-chlorophenylhydrazone of ethyl 2-oxobutanoate was prepared by adaptation of the Japp-Klingemann reaction as described by lions and Hughes (J. Proc. Roy. Soc. N. S. Wales 1939, 71: 445) to p-chloroaniline and ethyl 2-ethylacetoacetate. This phenylhydrazone was treated with HCl-ethanol according to the procedure of lions and Hughes (J. Proc. Roy. Soc. N. S. Wales 1939, 71: 445) as applied therein to the corresponding bromophenylhydrazone. The title substance was collected by filtration as an orange solid after suspending the concentrated residue in water. The title substance was collected by filtration as an orange solid

Conditions: temp:70.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A 2.2 M solution of zinc(II)chloride (6.05 mL, 13.32 mmol) in diethyl ether was added to tin(II)chloride (2.53 g, 13.32 mmol) and activated 4 Å molecular sieve pellets (612.8 mg) under argon. Then, 5-bromo-2-nitro-benzaldehyde (612.8 mg, 2.66 mmol) and ethyl 2-oxobutanoate (346.7 mg, 2.66 mmol) in ethanol (13 mL) were added to the reaction mixture via canula. The mixture was heated at 70° C. in an oil bath for three hours, then allowed to cool to room temperature, and carefully quenched with saturated sodium bicarbonate. Ethyl acetate was added and the mixture was filtered through Celite®. The filtrate was extracted with ethyl acetate and the organic layer was dried over anhydrous magnesium sulfate, then filtered and concentrated. The residue was purified by silica gel chromatography eluting with 1:6 ethyl acetate:hexanes to give 137.9 mg (18%) of ethyl 6-bromo-3-methyl-2-quinolinecarboxylate as a solid. 1H NMR (400 MHz, d6-DMSO): δ 8.30 (s, 1H), 8.27 (d, J=2 Hz, 1H), 7.99 (d, J=9 Hz, 1H), 7.88 (dd, J=9, 2 Hz, 1H), 4.41 (q, J=7 Hz, 2H), 2.54 (s, 3H), 1.35 (t, J=7 Hz, 3H). ESI-LCMS m/z 294 (M+H)+. to cool to room temperature carefully quenched with saturated sodium bicarbonate Ethyl acetate was added the mixture was filtered through Celite® The filtrate was extracted with ethyl acetate the organic layer was dried over anhydrous magnesium sulfate filtered concentrated The residue was purified by silica gel chromatography eluting with 1:6 ethyl acetate