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温度

0 °C

1-(Cyano-dimethyl-methyl)-1H-indole-2,6-dicarboxylic acid diethyl ester (238, 0.725 mmol) was suspended in 3 mL of MeOH and 2 mL of THF, and 188 mg (1.45 mmol) of CoCl2 was added. While the mixture was stirred in a 0° C. bath, 274 mg (7.25 mmol) of NaBH4 was carefully added in small portions. The cold bath was removed and the mixture was stirred for 30 min. The vessel was sealed and heated to 60° C. with stirring for 4 h. The mixture was cooled and partitioned between EtOAc and saturated aqueous NaHCO3. The organic phase was then washed with 1 M NaHSO4 and brine, dried with Na2SO4, filtered, and concentrated. The residue was chromatographed (1-5% MeOH in CH2Cl2) to provided 65 mg of 4,4-dimethyl-1-oxo-1,2,3,4-tetrahydro-pyrazino[1,2-a]indole-7-carboxylic acid ethyl ester. ESI-MS m/z 287 [M+H]+.

1. customThe cold bath was removed
2. stirringthe mixture was stirred for 30 min
3. customThe vessel was sealed
4. temperatureheated to 60° C.
5. stirringwith stirring for 4 h
6. temperatureThe mixture was cooled
7. custompartitioned between EtOAc and saturated aqueous NaHCO3
8. washThe organic phase was then washed with 1 M NaHSO4 and brine
9. dry with materialdried with Na2SO4
10. filtrationfiltered
11. concentrationconcentrated
12. customThe residue was chromatographed (1-5% MeOH in CH2Cl2)