Reactivity of fluorinated sulfur-containing heterocycles towards nucleophilic and oxidizing reagents

Synthesis and (spectro)electrochemistry of mixed-valent diferrocenyl–dihydrothiopyran derivatives

“…A similar behaviour was found for a series of sulphurcontaining heterocycles in which the oxidation of the sulphur atom has almost no impact on the geometrical parameters of the heterocycles. 54,55 The only bond distances which are somewhat influenced by oxidation are S-C Fc and S-CH 2 (Table 1), whereby the corresponding bonds in 3, as compared to 1, are shortened by 0.02 Å, as previously observed by Petrov. 54,55 In both compounds, the thiopyran ring adopts a half-chair con-formation to limit the steric repulsion between the different substituents ( Fig.…”

“…54,55 The only bond distances which are somewhat influenced by oxidation are S-C Fc and S-CH 2 (Table 1), whereby the corresponding bonds in 3, as compared to 1, are shortened by 0.02 Å, as previously observed by Petrov. 54,55 In both compounds, the thiopyran ring adopts a half-chair con-formation to limit the steric repulsion between the different substituents (Fig. 2).…”

“…34 Scheme sulfone 3 at ambient temperature in 21% yield (Scheme 1, Experimental section). 54 Compounds 1-3 are red solids soluble in common organic solvents. All three compounds are stable towards air and moisture in the solid state and in solution.…”

Reactions of polyfluorinated thietanes

“…The presence of two bands in IR spectra of 3a-f in 1070-1090 cm À1 region is consistent with the presence of two isomeric S-oxides and these values agree well with values reported for 2,2,4,4-tetrakis(trifluoromethyl)-1,3-dithiethane-1-oxide, -1,3-dioxide [13,15] and S-oxide of 3-thia-4,4-bis(trifluoromethyl)tricyclo[5.2.1.0 2,5 ]non-7-ene [12].…”

“…It should be pointed out, that despite relatively high reaction temperature and excess of oxidizing agent we could not find any evidence for the formation of the corresponding 1-S-dioxides, previously prepared by Smart and Middleton [10] by reaction of (CF 3 ) 2 C5 5SO 2 with vinyl ethers. Such high selectivity is quite unusual, since the oxidation of hydrocarbon analogs, such as 2,2,4,4-tetramethyl-3-aminothietane by MCPBA under similar conditions leads to high yield formation of the corresponding Sdioxides [11] and the oxidation of a close fluorinated analog 3-thia-4,4-bis(trifluoromethyl)-tricyclo[5.2.1.0 2,5 ]non-7-ene also proceeds with complete oxidation [12]. The only reported example of selective oxidation of fluorinated heterocycle is the reaction of 2,2,3,3-tetrakis-(trifluoromethyl)thiirane with CF 3 SO 2 OOH leading to the corresponding -1-S-oxide [13].…”