METHYL 5-(BENZYLOXYCARBONYL)-2,4-DIMETHYL-3-PYRROLEPROPIONATE

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: 4-(2-methoxycarbonyl-ethyl)-3,5-dimethyl-1H-pyrrole-2-carboxylic acid benzyl ester (390 mg, 1.24 mmol) was dissolved in anhydrous MeOH (20 mL). The solution was evacuated and rinsed with argon several times. 120 mg of palladium on charcoal (10%) were added and again the mixture was evacuated and rinsed with argon several times. Finally argon was exchanged by hydrogen (balloon filled with hydrogen) and the mixture was stirred for 3 h at room temperature. The reaction mixture was filtered over celite and the filter residue was washed with MeOH (150 mL). The filtrate was concentrated in vacuo to give pure 4-(2-methoxycarbonyl-ethyl)-3,5-dimethyl-1H-pyrrole-2-carboxylic acid as a colorless solid (263 mg). MS (ESI−): m/e=225 [M−H]−. The solution was evacuated rinsed with argon several times 120 mg of palladium on charcoal (10%) were added again the mixture was evacuated rinsed with argon several times The reaction mixture was filtered over celite the filter residue was washed with MeOH (150 mL) The filtrate was concentrated in vacuo

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

Procedure: 2-Benzyloxycarbonyl-3,5-dimethyl-4-(2-methoxycarbonylethyl)pyrrole (Aldrich, 2.0 g) was hydrogenated over 0.2 g of 10% palladium on carbon in 40 mL of methanol for 2 hours at room temperature. The catalyst was removed by filtration and washed with 40 mL of methanol. The filtrate was evaporated to dryness and dried overnight in a vacuum oven to give 1.3 g (92% yield) of 2-carboxy-3,5-dimethyl-4-(2-methoxycarbonylethyl)pyrrole. The catalyst was removed by filtration washed with 40 mL of methanol The filtrate was evaporated to dryness dried overnight in a vacuum oven

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

Procedure: Methyl 5-(benzyloxycarbonyl)-2,4-dimethyl-3-pyrrolepropionate (3.1 g, 9.8 mmol) was dissolved in acetone (100 mL). This solution was added with 10% Pd—C, and stirred at room temperature under hydrogen gas. When the starting material disappeared, the reaction mixture was filtered, and the filtrate was distilled under reduced pressure. The residue was added with trifluoroacetic acid (10 mL), and heated at 40° C. for 10 minutes under an argon flow. The reaction mixture was added with chloroform, and washed once with water, and the aqueous layer was extracted twice with chloroform. The organic phases were combined, washed once with aqueous Na2CO3 and once with water, dried over anhydrous Na2SO4, and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (developing solvent: CH2Cl2) to obtain the target compound as brown liquid (1.6 g, yield: 90%). the reaction mixture was filtered the filtrate was distilled under reduced pressure The residue was added with trifluoroacetic acid (10 mL) heated at 40° C. for 10 minutes under an argon flow The reaction mixture was added with chloroform washed once with water the aqueous layer was extracted twice with chloroform washed once with aqueous Na2CO3 and once with water dried over anhydrous Na2SO4 concentrated under reduced pressure The residue was purified by silica gel column chromatography (developing solvent: CH2Cl2)