Sodium borohydride → Rac-6-chloro-3-(3-chloro-benzyl)-1,3-dihydro-indol-2-one

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Reaction Steps

Sodium borohydride (12.4 g, 328 mmol) (Aldrich) was added in small portions to a suspension of E/Z-6-chloro-3-(3-chloro-benzylidene)-1,3-dihydro-indol-2-one (25 g, 86 mmol) (from Example 30a supra) in methanol (400 mL) at such a rate that gas evolution was not too vigorous. When addition was complete, mixture was stirred at room temperature for 3 hours. The solvent was evaporated under reduced pressure and the residue was partitioned between ethyl acetate and water. The aqueous layer was extracted with another two portions of ethyl acetate. The combined organic layers were washed with water, brine, dried over Na2SO4 and concentrated. The residue was purified by chromatography (ethyl acetate-dichloromethane, 1:2, V/V). The resulting yellow solid was recrystallized from ethyl acetate to give rac-6-chloro-3-(3-chloro-benzyl)-1,3-dihydro-indol-2-one as a pale yellow solid. (Yield 10 g, 40%).

Provenance & Evidence