Efficient and Stereoselective Syntheses of Isomerically Pure 4‑Aminotetrahydro‑2H‑thiopyran 1‑Oxide Derivatives

Efficient and stereoselective syntheses of isomerically pure 4-aminotetrahydro-2H-thiopyran 1-oxide derivatives have successfully been achieved. Isomerically pure (4-nitrophenyl)­sulfonyltetrahydro-2H-thiopyran 1-oxides were identified by X-ray crystallographic analyses, and isomerically pure sulfoxide derivatives were characterized by 1H NMR. An oxidation reaction of tert-butyl­(4-nitrophenyl)­sulfonyl­(tetrahydro-2H-thiopyran-4-yl)­carbamate with Oxone provided steric control, affording its trans sulfoxide with high efficiency and selectivity. From the obtained trans sulfoxide derivatives, cis sulfoxide derivatives were synthesized conveniently by a hydrogen chloride catalyzed isomerization.