C1CCCCC1.[C:7]([O:11][C:12]([N:14]1[C:22]2[C:17](=[C:18]([C:23]#[C:24][Si](C)(C)C)[CH:19]=[CH:20][CH:21]=2)[CH:16]=[C:15]1[CH3:29])=[O:13])([CH3:10])([CH3:9])[CH3:8].[OH-:30].[Na+].[OH:32]O>O1CCCC1>[C:7]([O:11][C:12]([N:14]1[C:22]2[CH:21]=[CH:20][CH:19]=[C:18]([CH2:23][C:24]([OH:32])=[O:30])[C:17]=2[CH:16]=[C:15]1[CH3:29])=[O:13])([CH3:10])([CH3:9])[CH3:8]A solution of cyclohexane (16.1 ml) in tetrahydrofuran (160 ml) was cooled at −10° C., and then to the mixture was added dropwise borane-tetrahydrofuran complex (1M, 80 ml), and the mixture was stirred at 0° C. for 1 hour. To the solution was added dropwise a solution of 1-t-butoxycarbonyl-2-methyl-4-(2-trimethylsilylethynyl)indole (13.1 g; prepared in Reference Example 3) in tetrahydrofuran (60 ml), the mixture was stirred for 1 hour at room temperature. To a reaction solution was added dropwise 3N aqueous solution of sodium hydroxide (40 ml) and 30% hydrogen peroxide (in water, 45 ml), successively, and the mixture was stirred for 12 hours. The reaction mixture was extracted with water—diethyl ether. The aqueous layer was adjusted to acidic condition with hydrochloric acid and then extracted with ethyl acetate. The extraction was washed with water and a saturated aqueous solution of sodium chloride, successively, dried and concentrated under reduced pressure to give the title compound (10.4 g; crude).
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