[CH2:1]([N:3]1[C:11]2[C:6](=[CH:7][C:8]([OH:15])=[C:9]([CH2:12][CH:13]=[CH2:14])[CH:10]=2)[CH2:5][C:4]1=[O:16])[CH3:2].B.O1CCCC1.[OH-].[Na+].OO>O1CCCC1>[CH2:1]([N:3]1[C:11]2[C:6](=[CH:7][C:8]3[O:15][CH2:14][CH:13]=[CH:12][C:9]=3[CH:10]=2)[CH2:5][C:4]1=[O:16])[CH3:2]
To a solution of 3.0 g. (13.8 mmoles) of 1-ethyl-5-hydroxy-6-allyloxindole (Preparation W2) in 30 ml. of tetrahydrofuran at 0° C. was slowly added 13.8 ml. (13.8 mmoles) of a 1M borane-tetrahydrofuran solution. The reaction was stirred for 30 minutes followed by the addition of 50 ml. of 1N sodium hydroxide solution and 25 ml. of a 30% hydrogen peroxide solution. After stirring the reaction for 5 minutes it was acidified with 25 ml. of 4N hydrochloric acid and extracted with methylene chloride (10×50 ml.). The extracts were combined, dried and concentrated to give the crude product, which was purified by chromatographing on 120 g. of silica gel using 5% methanol-methylene chloride as the eluent to give 1.85 g. (56% yield) of the desired product.
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