Ethanol → ethyl (3R)-4-benzoyl-8-(4-isopropylphenoxy)-1-thia-4-azaspiro[4.5]decane-3-carboxylate

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Reaction Steps

In 56 ml of methylene chloride was dissolved 2.80 g of (3R)-4-benzoyl-8-(4-isopropylphenoxy)-1-thia-4-azaspiro[4.5]decane-3-carboxylic acid, to which were successively added at 0-5° C. 0.56 ml of ethanol, 0.16 g of N,N-dimethylaminopyridine and 1.98 g of dicyclohexyl carbodiimide. After stirring the mixture at ambient temperature for 24 hours, the insoluble matter was filtered off. The filtrate was poured into ice water, pH was adjusted to 2.0 with 2 mol/L hydrochloric acid, and the organic layer was separated. The organic layer thus obtained was washed successively with water, saturated aqueous solution of sodium hydrogen carbonate and saturated aqueous solution of sodium chloride and dried over anhydrous magnesium sulfate, and the solvent was distilled off under reduced pressure. Purification of the residue by column chromatography [eluent: toluene:ethyl acetate=50:1] gave 0.85 g of ethyl (3R)-4-benzoyl-8-(4-isopropylphenoxy)-1-thia-4-azaspiro[4.5]decane-3-carboxylate as a colorless oily product.

Provenance & Evidence