Synthesis
General procedure for the synthesis of tetrahydro-1,4-thiopyran-5-one from tetrahydro-4H-thiopyran-4-one oxime: to an acetone/water (20 mL/20 mL) solution of compound 2 (1.0 g, 7.6 mmol) was added p-toluene sulfonyl chloride (TsCl, 2.16 g, 11.4 mmol) and sodium carbonate (Na2CO3, 1.2 g, 23.2 mmol). The reaction mixture was stirred at 60 °C for 16 hours. After completion of the reaction, the solvent was removed by concentration under reduced pressure. The residue was extracted with ethyl acetate (EA, 20 mL x 3). The organic layers were combined, dried over anhydrous sodium sulfate (Na2SO4), filtered and the filtrate was concentrated to give compound 3 (740 mg, 74% yield) as a white solid.
References
[1] Patent: US2015/197493, 2015, A1. Location in patent: Paragraph 0777; 0780; 0781
[2] Patent: WO2017/15106, 2017, A1. Location in patent: Page/Page column 28; 29
[3] Gazzetta Chimica Italiana, 1948, vol. 78, p. 207,216
[4] Journal of Organic Chemistry, 1955, vol. 20, p. 871,873
[5] Helvetica Chimica Acta, 1974, vol. 57, p. 2562 - 2571
