Sodium Hydroxide → 2,8-Dimethyl-1-oxa-8-azaspiro[4.5]decan-3-one

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Reaction Steps

Ethyl 2,8-dimethyl-3-oxo-1-oxa-8-azaspiro[4,5]decane-4-carboxylate (3.08 g) was dissolved in 50 ml of 1N-HCl, and the solution was heated under reflux for eight hours. The reaction mixture was allowed to cool to room temperature, then cooled in an ice-water bath, and basified by addition of 20% aqueous solution of caustic soda. This alkaline solution was extracted thrice with about 80 ml of chloroform, and the combined extract was washed with saturated aqueous solution of sodium chloride and dried over anhydrous magnesium sulfate. Distilling off the solvent under reduced pressure from the dried solution left 2 g of yellow residue, which was purified by silica gel column chromatography by using, as eluent, a mixed solvent of chloroform/methanol (20:1 by volume), giving 1.8 g of 2,8-dimethyl-1-oxa-8-azaspiro[4,5]decan-3-one as oil. It was dissolved in ether, and ethanolic hydrogen chloride was added, thus giving its hydrochloride as crystals.

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