8,8-difluoro-1,4-dioxaspiro[4.5]decane

4746-97-8

176251-49-3

The general procedure for the synthesis of 8,8-difluoro-1,4-dioxaspiro[4.5]decane from 1,4-cyclohexanedione monoethyleneglycol ketal was as follows: method B: Ketone 6 (4.40 g, 28.2 mmol) was dissolved in anhydrous CH2Cl2 (100 mL) under argon gas protection and cooled to 0 °C. Morph-DAST (11.85 g, 67.7 mmol, 2.4 eq.) was slowly added dropwise under stirring conditions. Subsequently, the reaction mixture was gradually warmed to room temperature and stirred continuously for 72 hours. Upon completion of the reaction, saturated aqueous NaHCO3 (50 mL) was added to quench the unreacted fluoride and stirring was continued for 10 minutes. The organic layer was separated and the aqueous phase was extracted with CH2Cl2 (2 x 50 mL). An aqueous solution (100 mL) of KMnO4 (5.7 g, 36 mmol, 10 eq.) was added to the combined organic phases, and the suspension formed was reacted for 24 hours under vigorous stirring. The organic layer was separated again and the aqueous phase was extracted with CH2Cl2 (2 x 100 mL). All organic phases were combined and dried with Na2SO4, followed by vacuum evaporation of the solvent at 30 °C to give pure compound 7 (3.65 g, 20.5 mmol, 73% yield) as a colorless oil, which was stored and crystallized.