Step i: Synthesis of 4,4-dimethyl-1,3-cyclohexanedione
To a 100 mL round bottom flask was added 3-methyl-2-butanone (5.0 g, 58.05 mmol), potassium tert-butanol (13.0 g, 116.1 mmol) and tetrahydrofuran (50 mL). The reaction mixture was cooled to 0 °C. Ethyl acrylate (5.8 g, 58.05 mmol) was slowly added dropwise at 0 °C. After the dropwise addition, the reaction mixture was stirred at room temperature for 20 minutes. Upon completion of the reaction, the reaction was quenched with saturated aqueous ammonium chloride solution and extracted with ethyl acetate (3 × 20 mL). The organic phases were combined, washed with saturated brine and dried over anhydrous sodium sulfate. The solvent was removed by concentration under reduced pressure to give the crude product. The crude product was purified by column chromatography (silica gel 60-120 mesh, eluent: hexane solution of 50% ethyl acetate) to afford 4,4-dimethyl-1,3-cyclohexanedione (4.0 g, 49.2% yield).
NMR (300 MHz, CDCl3): δ 3.28 (s, 2H), 2.64 (t, 2H), 1.87 (t, 2H), 1.22 (s, 6H);
LC-MS: 141.0 [M + H]+.
