[Synthesis]
GENERAL STEPS: To a solution of methyl vinyl sulfone (10.0 g, 94 mmol) in benzene (50 mL) was added 2-trimethylsiloxy-1,3-butadiene (14.07 g, 99 mmol) and hydroquinone (20 mg, 0.182 mmol). The mixture was degassed several times at -78 °C and subsequently heated. The reaction mixture was sealed and heated at 105 °C for 48 hours. The reaction process was analyzed by nuclear magnetic resonance (NMR) in deuterated chloroform (CDCl3), showing about 10% residual methyl vinyl sulfone. 2-Trimethylsilyloxy-1,3-butadiene (4 mL) was added additionally and heating was continued for 48 h. NMR analysis was performed again after 72 h and showed that the amount of methyl vinyl sulfone was further reduced to 3%. The sample in the NMR tube was combined with the reaction mixture and concentrated under vacuum at room temperature (19 °C) to a viscous gel. The mixture was re-diluted with acetone (250 mL) to obtain a clarified solution. The mixture was cooled in an ice bath. Pre-cooled 0.25 N HCl (4 mL) was added to form a turbid mixture, which became clear after stirring at 0°C for 15 min, then became turbid again within 10 min and remained turbid for the remaining stirring time. A 50 μL aliquot was taken, quickly dried to form a film, and analyzed by NMR in CDCl3, showing a 7% residue of methyl vinyl sulfone relative to the target product, 4-methylsulfonylcyclohexyl ketone. After a total reaction time of about 1 hour, the acetone solution was filtered through a bed of H-short silica gel and washed with more acetone. The filtrate was concentrated on a rotary evaporator at 19°C bath temperature. The crude product was divided into two portions of 7.75 g each for subsequent purification. Purification by silica gel column chromatography (elution gradient: 30% ethyl acetate/hexane to 100% ethyl acetate; two 330 g silica gel columns were used) afforded 4-methanesulfonylcyclohexyl ketone (16.7 g, 100% yield) as a white solid.1H NMR (400 MHz, CDCl3) δ 3.29 (tt, J = 11.0, 3.9 Hz, 1H), 1H 2.94 (s, 3H), 2.73-2.62 (m, 2H), 2.58-2.37 (m, 4H), 2.15 (qd, J = 11.9, 4.5 Hz, 2H). |