Some representatives of the class of sulfur-containing organic compounds, including derivatives of sulfones [1], dialkyldisulfides [2], and 3-thiabicyclohexanecarboxylic acid [3], were reported to possess anti-inflammatory activity. Biological activity is also inherent in 1,2,5-thiadiazole and its condensed derivatives, which act upon central nervous system and influence tissue metabolism [4].In continuation of our investigations into new bicyclic bis-sulfoxides, we have synthesized 4-methyl-1-(methylsulfinylmethyl)-7-thiabicyclo[3.3.1]non-3-en-2-one-7-oxide (I) and studied the anti-inflammatory and antiarrhythmic properties of this compound.The synthesis I was conducted according to the scheme depicted below. In the first step, we obtained 4-methyl-1-(methylthiomethyl)-7-thiabicyclo[3.3.1]non-3-en-2-one (II) via alkylthiomethylation of propanone with a mixture of formaldehyde, methylmercaptan, and sodium sulfide in an alkaline medium [5]. In the second step, compound II was oxidized in a 28 -30% aqueous hydrogen peroxide solution at 20°C, and the target compound I was obtained with a yield of 95%.The purity and the proposed structures of the synthesized compounds were confirmed by the results of elemental analyses and by the data of IR, 1 H NMR, and 13 C NMR spectroscopy (Tables 1 and 2). The IR spectra of compounds I and II exhibit absorption bands at 1656, 1618, 1624, and 1654 cm -1 characteristic of the stretching vibrations of the C=O and C=C bonds [6].In the 13 C NMR spectrum of compound I, the signals from carbon atoms C 6 (48.43 and 48.54 ppm), C 8 (56.75 and 56.06 ppm), C 11 (62.62 and 61.52 ppm), and C 13 (36.08 and 35.79 ppm) are shifted toward lower fields as compared to the analogous signals in the spectrum of compound II (Table 2). In addition, almost all signals in the 13 C NMR spectrum of compound I are doubled, which is indicative of the existence of two isomers. The spectra were assigned separately to each isomer. The appearance of a diastereomer pair is related to the presence of a chiral carbon atoms C 1 and a pyramidal sulfoxide sulfur atom in the aliphatic substituent, which make possible the formation of two d-diastereomers with R*R* and R*S* centers [7].The 1 H C NMR spectrum of compound I displays clearly distinguished signals due to the greater isomer and shows the signals from diastereotopic protons at C 11 in the form of two doublets with a geminal spin -spin coupling constant of 13.3 Hz and a relative chemical shift Dd = 0.61 ppm. For the second diastereomer, this difference is below 0.29 ppm. Based on the published data [7], the diastereomer with a greater difference of the chemical shifts is identified as the erythro isomer (Ia), while the component with a smaller Dd value is identified as the threo isomer (Ib). Both isomers are 659
