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Condensation of methyl 3 ,4-diaminobenzoate with diethyl oxalate (8.0 equivalents) in toluene (10 volumes) was carried out at reflux for 88 hours. After complete conversion, the mixture was concentrated to a residue which was washed with MTBE. After drying intermediate 184 was obtained in 90percent yield.
90%
for 88 h; Reflux
Condensation of methyl 3,4-diaminobenzoate with diethyl oxalate (8.0 equivalents) in toluene (10 volumes) was carried out at reflux for 88 hours. After complete conversion, the mixture was concentrated to a residue which was washed with methyl tert-butyl ether. After drying intermediate 25 was obtained in 90percent yield.
Condensation of methyl 3 ,4-diaminobenzoate with diethyl oxalate (8.0 equivalents) in toluene (10 volumes) was carried out at reflux for 88 hours. After complete conversion, the mixture was concentrated to a residue which was washed with MTBE. After drying intermediate 184 was obtained in 90% yield.
90%
In toluene; for 88.0h;Reflux;
Condensation of methyl 3,4-diaminobenzoate with diethyl oxalate (8.0 equivalents) in toluene (10 volumes) was carried out at reflux for 88 hours. After complete conversion, the mixture was concentrated to a residue which was washed with methyl tert-butyl ether. After drying intermediate 25 was obtained in 90% yield.
for 3.0h;Heating / reflux;
Step A A mixture of methyl-3,4-diaminobenzoate (4.5 g) in diethyloxalate (50 ML) was heated at reflux for three hrs.After cooling to 23 C., the solid was isolated by filtration, affording 2,3-dioxo-1,2,3,4-tetrahydro-quinoxaline-6-carboxylic acid methyl ester as a light yellow solid. MS (M-H)-=219.1.
With thionyl chloride; N,N-dimethyl-formamide; In thionyl chloride; N,N-dimethyl-formamide; at 23℃; for 18.0h;Heating / reflux;
Step B DMF (5 drops) was added to a suspension of 2,3-dioxo-1,2,3,4-tetrahydro-quinoxaline-6-carboxylic acid methyl ester (650 mg) in thionyl chloride (6.7 ML) at 23° C. The reaction mixture was then heated to reflux for 18 hrs.After cooling to 23° C. and concentration, the residue was dissolved in chloroform and washed sequentially with portions of saturated aqueous sodium bicarbonate and brine.Drying over sodium sulfate and concentration afforded 2,3-dichloro-quinoxaline-6-carboxylic acid methyl ester as a white solid. MS (M+H)+=257.1.
Intermediate 184 was dissolved in 1,2-dichloroethane (10 volumes). Then, dimethylformamide was added (1.0 equivalent) followed by thionyl chloride (4.0 equivalents). The mixture was heated to 80 C for 3 hours, cooled to 15 C and water (5 volumes) was slowly added. After phase separation, the organic layer was washedtwice with water (10 volumes) and the solvent was exchanged to 2-Me-THF (15 volumes). Triethylamine was added (3.0 equivalents) followed by morpholine (1.0 equivalents) and the reaction was stirred at room temperature. After complete conversion, water (10 volumes) was added and the leyers were separated. Then, the aqueous phase was washed with 2-MeTHF (5 volumes). The combined organic layerswere washed with water (5 volumes), concentrated to a residue to obtain a solid which was slurried in MTBE (5 volumes). The precipitate was filtered and dried to give intermediate 185 in 70% yield.
70%
Intermediate 25 was dissolved in 1 ,2-dichloroethane (10 volumes). Then, dimethylformamide was added (1.0 equivalent) followed by thionyl chloride (4.0 equivalents). The mixture was heated to 80 C for 3 hours, cooled to 15 C and water (5 volumes) was slowly added. After phase separation, the organic layer was washed twice with water (10 volumes) and the solvent was exchanged to Me-THF (15 volumes). Triethylamine was added (3.0 equivalents) followed by morpholine (1.0 equivalents) and the reaction was stirred at room temperature. After complete conversion, water (10 volumes) was added and the leyers were separated. Then, the aqueous phase was washed with Me-THF (5 volumes). The combined organic layers were washed with water (5 volumes), concentrated to a residue to obtain a solid which was slurried in methyl tcrt-butyl ether (5 volumes). The precipitate was filtered and dried to give intermediate 26 in 70% yield.
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