ethyl 6-chloro-1H-indole-2-carboxylate

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 stirred suspension-solution of ethyl 6-chloroindole-2-carboxylate (20.0 g, 89.4 mmol) in methanol (350 mL) under Ar was added magnesium turnings (21.7 g, 0.89 mol). After 10 min, the internal temperature had risen to 24° C. and effervescence was apparent. The mixture was to 10-15° C. and was maintained for 1.5 h. After this time, the reaction mixture was allowed to warm to ambient temperature, and was stirred for 1 h. The mixture was poured onto saturated aqueous ammonium chloride solution (1 L), and ethyl acetate (300 mL) was added. After 1.5 h sting, the layers were separated, and the aqueous layer was extracted with ethyl acetate (2×300 mL). The combined organic extracts were washed with brine (200 mL), dried (magnesium sulfate) and concentrated in vacuo to give a brown oil. Purification by flash column chromatography [SiO2; ethyl acetate-heptane (1:3)] afforded the title compound (12.0 g, 63%) as an orange oil which crystallised on standing: IR νmax (film)/cm−1 3375, 2953, 2851, 1737, 1610, 1486, 1438, 1321, 1287, 1204, 1161, 1069, 1011, 948, 906, 846, 796, 794, 594 and 548; NMR δH (400 MHz; CDCl3) 3.27 (1H, dd, J 16.0, 5.0 Hz), 3.34 (1H, ddd, J 16.0, 10.5, 1.0 Hz), 3.76 (3H, s), 4.40 (1H, dd, J 10.5, 5.0 Hz), 4.47 (1H, br s), 6.68 (1H, br d, J 2 Hz), 6.69 (1H, dd, J 7.5, 2.0 Hz) and 6.96 (1H, d, J 7.5 Hz); hplc [Chiralcel OD; hexane-isopropanol (90:10); 1 mL/min; 260 nm] 50% (10.04 min) and 5% (11.61 min). had risen to 24° C. was to 10-15° C. was maintained for 1.5 h was added After 1.5 h sting the layers were separated the aqueous layer was extracted with ethyl acetate (2×300 mL) The combined organic extracts were washed with brine (200 mL) dried (magnesium sulfate) concentrated in vacuo to give a brown oil Purification by flash column chromatography [SiO2; ethyl acetate-heptane (1:3)]

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

Procedure: To a stirred suspension-solution of ethyl 6-chloroindole-2-carboxylate (20.0 g, 89.4 mmol) in methanol (350 mL) under Ar was added magnesium turnings (21.7 g, 0.89 mol). After 10 min, the internal temperature had risen to 24° C. and effervescence was apparent. The mixture was cooled to 10-1S ° C. and was maintained for 1.5 h. After this time, the reaction mixture was allowed to warm to ambient temperature, and was stirred for 1 h. The mixture was poured onto saturated aqueous ammonium chloride solution (1 L), and ethyl acetate (300 mL) was added. After 1.5 h stirring, the layers were separated, and the aqueous layer was exacted with ethyl acetate (2×300 mL). The combined organic extracts were washed with brine (200 mL), dried (magnesium sulfate) and concentrated in vacuo to give a brown oil. Purification by flash column chromatography [SiO2; ethyl acetate-heptane (1:3)] afforded the title compound (12.0 g, 63%) as an orange oil which crystallised on standing: IR νmax (film)t/cm−1 3375, 2953, 2851,1737, 1610, 1486, 1438, 1321, 1287, 1204, 1161, 1069, 1011, 948, 906, 846, 796, 794, 594 and 548; NMR δH (400 MHz; CDCl3) 3.27 (1H, dd, J 16.0, 5.0 Hz), 3.34 (1H, ddd, J 16.0, 10.5, 1.0 Hz), 3.76 (3H, s), 4.40 (1H, dd, J 10.5, 5.0 Hz), 4.47 (H, br s), 6.68 (1H, br d, J 2 Hz), 6.69 (1H, dd, J 7.5, 2.0 Hz) and 6.96 (1H, d, J 7.5 Hz); hplc [Chiralcel OD; hexane-isopropanol (90:10); 1 mL/min; 260 nm] 50% (10.04 min) and 50% (11.61 min). had risen to 24° C. The mixture was cooled to 10-1S ° C and was maintained for 1.5 h was added After 1.5 h stirring the layers were separated The combined organic extracts were washed with brine (200 mL) dried (magnesium sulfate) concentrated in vacuo to give a brown oil Purification by flash column chromatography [SiO2; ethyl acetate-heptane (1:3)]

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 solution of 2.00 g (8.94 mmol) 6-chlorindole-2-carboxylic acid ethyl ester in 50 ml diethyl ether were added 0.475 g (12.5 mmol) lithium aluminum hydride at 0° C. The reaction mixture was heated at reflux for 45 min and quenched by consecutive addition of 10 ml water, 10 ml aqueous 2 M sodium hydroxide solution and 10 ml water at 0° C. The aqueous layer was extracted with tert-butyl methyl ether (3×100 ml). The combined organic layers were dried over sodium sulfate and concentrated in vacuo to give the crude title compound (1.64 g; 100%) as a white solid. The reaction mixture was heated at reflux for 45 min quenched by consecutive addition of 10 ml water, 10 ml aqueous 2 M sodium hydroxide solution and 10 ml water at 0° C The aqueous layer was extracted with tert-butyl methyl ether (3×100 ml) The combined organic layers were dried over sodium sulfate concentrated in vacuo

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

Procedure: To 6-chloro-1H-indole-2-carboxylic acid ethyl ester (8.57 g) in THF at 0° C. was added lithium aluminum hydride solution (1M, in THF) dropwise and the reaction mixture was stirred for 3.5 h. The mixture was quenched with H2O, 15% NaOH, and H2O before it was filtered and rinsed with THF. Evaporation of the solvent gave 7.77 g of the crude (6-Chloro-1H-indol-2-yl)-methanol which was used directly in the next step. The mixture was quenched with H2O, 15% NaOH, and H2O before it was filtered rinsed with THF Evaporation of the solvent

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

Procedure: To crude 3-(4-chloro-2-nitro-phenyl)-2-oxo-propionic acid ethyl ester (151 mmol) in ethanol:glacial HOAc (1:1, v/v, 560 mL) at rt was added iron powder (74.4 g) and the reaction mixture was stirred at reflux for 4 h. The mixture was filtered and evaporated to give a residue which was redistributed in dichloromethane/1N HCl. The organic layer was washed with 1N HCl, NaHCO3, and brine and dried. Evaporation followed by crystallization (DCM) gave 6-Chloro-1H-indole-2-carboxylic acid ethyl ester as a pale yellow solid (16.8 g, 50% over 2 steps). at reflux for 4 h The mixture was filtered evaporated to give a residue which The organic layer was washed with 1N HCl, NaHCO3, and brine dried Evaporation followed by crystallization (DCM)

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

Procedure: To crude 3-(4-chloro-2-nitro-phenyl)-2-oxo-propionic acid ethyl ester (151 mmol) in ethanol:glacial HOAc (1:1, v/v, 560 mL) at rt was added iron powder (74.4 g) and the reaction mixture was stirred at reflux for 4 h. The mixture was filtered and evaporated to give a residue which was redistributed in dichloromethane/1N HCl. The organic layer was washed with 1N HCl, NaHCO3, and brine and dried. Evaporation followed by crystallization (DCM) gave 6-Chloro-1H-indole-2-carboxylic acid ethyl ester as a pale yellow solid (16.8 g, 50% over 2 steps). at reflux for 4 h The mixture was filtered evaporated to give a residue which The organic layer was washed with 1N HCl, NaHCO3, and brine dried Evaporation followed by crystallization (DCM)

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

Procedure: To 6-chloro-1H-indole-2-carboxylic acid ethyl ester (8.57 g) in THF at 0° C. was added lithium aluminum hydride solution (1M, in THF) dropwise and the reaction mixture was stirred for 3.5 h. The mixture was quenched with H2O, 15% NaOH, and H2O before it was filtered and rinsed with THF. Evaporation of the solvent gave 7.77 g of the crude (6-Chloro-1H-indol-2-yl)-methanol which was used directly in the next step. The mixture was quenched with H2O, 15% NaOH, and H2O before it was filtered rinsed with THF Evaporation of the solvent