58093-05-3

141-82-2

120-92-3

58093-05-3

The general procedure for the synthesis of 6,10-dioxaspiro[4.5]decane-7,9-dione from malonic acid and cyclopentanone is as follows: 1. In a dry reaction flask, 11.4 g (0.1095 mol) of malonic acid was dissolved in 25 mL of acetic anhydride, three drops of concentrated sulfuric acid was added as a catalyst, and the reaction was stirred for 2 hours at room temperature. 2. 9.7 mL (0.1095 mol) of cyclopentanone was slowly added to the above reaction mixture and stirring was continued at room temperature overnight. 3. Upon completion of the reaction, excess acetic anhydride was removed under reduced pressure using a rotary evaporator. 4. The residue was ground with hexane and the solid was collected by filtration. 5. The crude product was dissolved in ether and hexane was added slowly until brown crystals were observed, which were removed by filtration. 6. The filtrate was allowed to stand until white crystals precipitated, the crystals were collected using a sintered glass filter and washed with hexane. 7. After drying, 11.5 g (62% yield) of the target product 6,10-dioxaspiro[4.5]decane-7,9-dione was obtained. Product characterization: melting point 68 °C; mass spectrum (negative ion mode) ES (M-H)- 169; elemental analyses were in agreement with the theoretical values (C8H10O4-0.25H2O): calculated values C 55.01%, H 6.06%, N 0.00%; measured values C 54.75%, H 5.90%, N 0.00%. 1H-NMR (DMSO-d6) δ: 4.0 (s, 2H), 2.1 (m, 4H), 1.7 (m, 4H).