[CH3:1][O:2][C:3]1[C:8]([C:9]2[C:22]3[C:17](=[CH:18][C:19]([O:25][CH2:26][CH3:27])=[C:20]([O:23][CH3:24])[CH:21]=3)[CH:16]3[CH:11]([CH2:12][CH2:13][CH:14]([O:28]C(=O)C)[CH2:15]3)[N:10]=2)=[CH:7][CH:6]=[C:5]([O:32][CH3:33])[N:4]=1.CO.C(=O)([O-])[O-].[Cs+].[Cs+]>ClCCl>[CH3:1][O:2][C:3]1[C:8]([C:9]2[C:22]3[C:17](=[CH:18][C:19]([O:25][CH2:26][CH3:27])=[C:20]([O:23][CH3:24])[CH:21]=3)[CH:16]3[CH:11]([CH2:12][CH2:13][CH:14]([OH:28])[CH2:15]3)[N:10]=2)=[CH:7][CH:6]=[C:5]([O:32][CH3:33])[N:4]=1423 mg of acetic acid (2RS,4aRS,10bRS)-6-(2,6-dimethoxy-pyridin-3-yl)-9-ethoxy-8-methoxy-1,2,3,4,4a,10b-hexahydro-phenanthridin-2-yl ester (compound 18) dissolved in 1 ml of dichloro-methane and 9 ml of methanol are added to 152 mg of cesium carbonate and the solution stirred for 19 h. The reaction mixture is adsorbed to silica gel and purified by flash chromatography to give 229 mg of the title compound as a colourless foam.
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