Step 2: Synthesis of 4-oxocyclohexanecarboxaldehyde; 8-(methoxymethylene)-1,4-dioxaspiro[4.5]decane (30 g, 0.16 mol) was dissolved in 1,4-dioxane (60 mL), H2O (30 mL) was added and concentrated. To this solution, HCl solution (120 mL, 1.4 mol) was slowly added at room temperature. The reaction mixture was stirred for 1 hour at room temperature. Upon completion of the reaction, liquid-liquid partition extraction was performed with ethyl acetate (150 mL) and H2O (150 mL). The organic layer was separated, dried with anhydrous Na2SO4 and concentrated under reduced pressure to give the crude product 4-oxocyclohexanecarboxaldehyde (15.3 g, 86.9% yield) as a colorless oil. The crude product was directly used in the next reaction without further purification.1H NMR (400 MHz, CDCl3) δ 9.71 (s, 1H), 2.64-2.62 (m, 1H), 2.41-2.29 (m, 5H), 2.20-2.15 (m, 2H), 1.94-1.89 (m, 2H).
![1,4-Dioxaspiro[4.5]decane, 8-(methoxymethylene)-](/CAS/GIF/96184-80-4.gif)
