Dimethyl Sulfoxide → Camphor

Participants

Reaction Steps

To a well-stirred solution of anhydrous CH2Cl2 (5 mL) under an argon atmosphere at −30° C. was added oxalyl chloride (0.14 mL, 1.6 mmol). Fluorous DMSO (1.0 g, 3.2 mmol) then was added dropwise, and the reaction mixture stirred for an additional 20 minutes. Isoborneol (0.153 g, 1 mmol) dissolved in CH2Cl2 (5 mL) then was added to this solution, followed, after an additional 40 min to 1 hour, by diisopropylethylamine (0.88 mL, 5 mmol). The reaction mixture then was warmed to room temperature and stirred for 30 minutes before quenching with water, washing with ammonium chloride (5 mL), extracting with CH2Cl2 (10 mL), and careful concentration under aspirator vacuum in a cold water bath. The reaction mixture then was dissolved in toluene (6 mL) and extracted continuously, with FC72 (15 mL) in a cooled continuous extractor for 4 hours (see, D. Crich et al., “Design, Synthesis, Application and Recovery of a Minimally Fluorous Diaryl Diselenide for the Catalysis of Stannane-Mediated Radical Chain Reactions,” Tetrahedron, 55 , pp. 14261-14268 (1999)). After decantation, concentration of the toluene layer and chromatography on silica gel yielded camphor (0.142 g, 94%). The FC72 phase, containing a mixture of fluorous. DMS and fluorous DMSO, then was stirred with methanol (3 mL) and hydrogen peroxide (0.23 mL of 30 %, 2 mmol) for 1 hour followed by dilution with water (5 mL), and extraction with CH2Cl2 (10 mL) in a three phase system. Concentration of the CH2Cl2 layer gave recovered crystalline fluorous DMSO (0.9 g, 90%).

Provenance & Evidence