Oxidation of 1,1′-[3-(methylsulfanylmethyl)tetrahydro-2H-thiopyran-3,5-diyl]diethanone with equivalent amounts of potassium iodate in glacial acetic acid and hydrogen peroxide in tetrahydrofuran and chloroform gave the corresponding mono-and disulfoxides and disulfone, respectively. Reactions of the title compound with sodium tetrahydridoborate and hydroxylamine hydrochloride afforded mono-and dihydroxy derivatives and monooxime, respectively.Four-component condensation of acetone with formaldehyde and sodium sulfide and methanethiolate that are components of alkaline sulfide solutions at gas processing plants was used to develop convenient procedures for the preparation of 1,1′-[3-(methylsulfanylmethyl)tetrahydro-2H-thiopyran-3,5-diyl]diethanone (I) and 8-methyl-5-(methylsulfanylmethyl)-3-thiabicyclo[3.3.1]non-7-en-6-one [1, 2] as promising starting compounds in the synthesis of polyfunctional heterocycles [3,4], including those possessing biological activity [5].In the present work we studied oxidation of the sulfur atoms and reduction and oximation of the oxo groups in 1,1′-[3-(methylsulfanylmethyl)tetrahydro-2H-thiopyran-3,5-diyl]diethanone (I). Oxidation of compound I to sulfoxide under conditions of potentiometric iodatometry [6] revealed nonequivalence of the sulfur atoms in I with respect to the oxidant. The titration curve contained two potential jumps at 670-820 and 840-910 mV, which corresponded to consumption of two oxygen atoms per tetrahydrothiopyran molecule I and successive oxidation of the sulfur atoms (see figure).Nonequivalence of the sulfur atoms in I was also confirmed by reactions with oxidants (Scheme 1). By oxidation of compound I with 1 equiv of potassium iodate in glacial acetic acid and with 2 equiv of hydrogen peroxide in tetrahydrofuran we obtained watersoluble sulfoxide II and disulfoxide III in 70 and 92% yield, respectively. According to the 1 H and 13 C NMR data, just the side-chain sulfur atom in sulfoxide II was oxidized.Selective formation of sulfoxide II was also observed in the oxidation of I with 1 equiv of hydrogen peroxide in acetone; however, the conversion of the initial compound did not exceed 45%. Increase in the amount of the oxidant, temperature, and reaction time resulted in the formation of a mixture of mono-and disulfoxides II and III and unreacted initial compound I (see table). The oxidation of I with 4 equiv of hydrogen peroxide in chloroform afforded disulfone IV in 98% yield.Compound I was reduced with 2 equiv of sodium tetrahydridoborate in aqueous ethanol to obtain hydroxy ketone V in 98% yield. Analogous reaction with 4 equiv of the reducing agent in aqueous methanol gave 92% of dihydroxy derivative VI. Treatment of diketone I with 2 equiv of hydroxylamine hydrochloride in aqueous ethanol in the presence of sodium acetate led to the formation of monooxime VII in 95% yield. We failed to obtain the corresponding dioxime. The reduction and oximation initially involves spatially more accessible carbonyl group in the acetyl substituent attached to C 5 of the th...