Water → 1-(2-(Trimethylsilyl)ethyl) 1'-tert-butyl 5-(3-ethoxy-2-(ethoxycarbonyl)-3-oxopropyl)spiro[indoline-3,3'-pyrrolidine]-1,1'-dicarboxylate

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Reaction Steps

Diethyl malonate (183 mg, 1.14 mmol) was dissolved in ethanol (2 mL). Thereafter, sodium ethoxide (78.0 mg, 1.15 mmol) and an ethanol (2 mL) solution of 1-(2-(trimethylsilyl)ethyl) 1′-tert-butyl 5-(bromomethyl)spiro[indoline-3,3′-pyrrolidine]-1,1′-dicarboxylate (390 mg, 0.76 mmol) were added to the above obtained solution under cooling on ice, and the thus obtained mixture was then stirred at the same temperature as above for 1.5 hours. Thereafter, water was added to the reaction solution, and the mixed solution was then extracted with ethyl acetate. The organic layer was washed with brine, and was then dried over anhydrous sodium sulfate, followed by concentration in vacuo. The obtained residue was purified by silica gel column chromatography (hexane:ethyl acetate=3:1) to obtain 1-(2-(trimethylsilyl)ethyl) 1′-tert-butyl 5-(3-ethoxy-2-(ethoxycarbonyl)-3-oxopropyl)spiro[indoline-3,3′-pyrrolidine]-1,1′-dicarboxylate (300 mg, 67%) in the form of a colorless amorphous product.

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