Citric Acid → 8-Ethyl-1,4-dioxaspiro[4,4]nonane-7-carboxylic acid

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Reaction Steps

A round bottom flask was charged with ethyl 8-ethyl-1,4-dioxaspiro[4.4]nonane-7-carboxylate (0.32 g, 1.4 mmol) and aqueous sodium hydroxide (1 N, 14.0 mL, 14.0 mmol). The solution was stirred overnight at rt. To the solution was added DCM (30 mL) followed by the addition of 20% aqueous citric acid (about 20 mL) to reach pH of about 2. The layers were separated and the aqueous solution was extracted with DCM (2×30 mL) and DCM/EtOAc (1:1, 30 mL). The combined extracts were dried over anhydrous MgSO4, filtered, and concd under reduced pressure to give 8-ethyl-1,4-dioxaspiro[4.4]nonane-7-carboxylic acid as a clear, colorless oil (0.27 g, 96%): LC/MS (Table 1, Method c) Rt=1.20 min; MS m/z: 201 (M+H)+.

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