Thiane dioxides

A useful method of utilizing vinyl sulfones (specifically methyl styryl sulfones) for the preparation of thiane dioxides in good yields is illustrated in equation 125333. 

Thiadiazoline S-oxides, synthesis of 275 Thiane dioxides formula of 382 synthesis of 468 Thiane oxides 750-752 conformational analysis of 465-467 formula of 382... 

In the equilibrium mixtures of thiane oxide (2) and 1,3-, 1,4-dithiane dioxides (3) and (4), the axial conformers are present predominantly over the equatorial conformers at low temperatures (— 90 °C). For instance in the monoxide (2) a ratio of 62% axial and 48% equatorial conformers has been observed. The prevalence of the axial conformers in the sulphoxides (2) and (4) has been explained to be due to hydrogen bonds between the oxygen in the axial sulphinyl group and the hydrogen atom at the 3-position as shown in Scheme 7121 127. 

It appears that the ketone enolates add to the vinyl sulfone, followed by a condensation that leads to the thiane sulfone. The latter may be desulfonylated to provide olefins Similarly, enamino vinyl sulfones (345) can undergo a thermally allowed electrocyclic reaction between the termini of the enaminic double bond and the allyl sulfonyl portion in the intermediate anion (346) to afford a, ) -unsaturated thiene dioxides (348) as shown in equation 126 ... 

Electrocatalytic formation of Me SO from DMSO was effected using cw-[Ru(0) (py)(bpy)2] VPt electrode/water-DMSO cf. mech. Ch. 1 [113], Oxidation of thian-threne-5-oxide by RuO /aq. Na(IO )/CCyO°C gave a mixture of the sulfone and thianthrene-5,5-dioxide with minor amounts of the disulfoxide and also thian-threne-5,5,10-trioxide comparisons were made between the behaviour of RuO, CrOjClj and [MnO ] for these reactions cf. mech. Ch. 1) [114]. 

The order of decreasing Lewis basicity toward trimethylaluminum is thiane, thiolane, diethyl (or dimethyl) sulfide, thietane and 2-methylthiirane (67IC1461). Thietane can be protonated at -60 °C with fluorosulfonic acid in antimony pentafluoride-liquid sulfur dioxide the NMR spectrum shows bands at 8 7.40 (S—H) and 3.20-4.40 p.p.m. (C—H) (71JOC1121). 

Very recently, the HF, MP2, and DFT calculated conformational equilibria of 4-X substituted thiane-1,1-dioxides (X = Me, CH2OH, COCH3, COC2H5, CN, F, Cl, Br, and OCOCH3) were published (02STC115). 

Thiadiazol 2,2-Dimethyl-5-(3,3,5,5-tetramethyl-thian-l,1-dioxid-4-yliden)-2,5-dihydro-E14a/3, 528 (R2C = C = S +... 

The increased axial preference relative to that observed in thiane-1-oxide, but comparable to that observed in the oxathiane analogue (see Section 3.3.3), could support the influence of an electrostatic attraction between the sulfinyl oxygen atom and the syn-diaxial hydrogen atoms (Scheme 3.48). Interestingly, trans-1,4-dithiane-1,4-dioxide (37) possesses a diaxial oxygen conformation in the solid state [80] and appears to exist preferentially in the same conformation in solution [81] (Scheme 3.49). 

Thiolans, Thians, Thiepans, Thiocans, their Oxides and Dioxides, and their Selenium Analogues... 

Cycloadditions involving unsaturated five- and six-membered rings containing sulphur have offered convenient routes to thiolan and thian derivatives. 3-Thiabicyclo[3,l,0]hexane 3,3-dioxide (27a) and its 2-methyl-and cij -2,4-dimethyl-derivatives (27b) and (27c) have been synthesized from the appropriate thiolen 1,1-dioxides by cycloaddition of diazomethane... 

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