P(Cl)(Cl)(OCl)=O.[CH2:7]([N:14]1[C:22]2[C:17](=[CH:18][CH:19]=[C:20]([CH2:23][C:24]([O:26][CH3:27])=[O:25])[CH:21]=2)[CH:16]=[CH:15]1)[C:8]1[CH:13]=[CH:12][CH:11]=[CH:10][CH:9]=1.[OH-].[Na+].CN(C)[CH:32]=[O:33]>>[CH2:7]([N:14]1[C:22]2[C:17](=[CH:18][CH:19]=[C:20]([CH2:23][C:24]([O:26][CH3:27])=[O:25])[CH:21]=2)[C:16]([CH:32]=[O:33])=[CH:15]1)[C:8]1[CH:9]=[CH:10][CH:11]=[CH:12][CH:13]=118 mg (0.12 mmol) of phosphoryl oxychloride was added gradually to 4 ml of a solution of 25 mg (0.09 mmol) of methyl (1-benzylindol-6-yl)acetate, as obtained in a) above, in dimethyl formamide, at room temperature, and the resulting mixture was stirred for 30 minutes. After this time, an excess of a 2N aqueous solution of sodium hydroxide was added to the mixture, which was then stirred for 10 minutes. The aqueous layer was extracted with methylene chloride and the extract was washed with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate and then the solvent was removed by evaporation under reduced pressure. The residue was subjected to column chromatography (eluent: a 25% v/v solution of ethyl acetate in hexane) to yield 23 mg (83%) of the title compound as an oil.
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