1,4-Thioxane, oxidation

Thiophene, dioxirane oxidation, 1156 Thiourea, dialkyl peroxide synthesis, 706 1,4-Thioxane, oxidation, 805-6 Thiyl radicals, triplet oxygen domino reactions, 221-3, 224, 225, 226 THPO (1,2,3,4-tetrahydronaphthyl hydroperoxide), 331-2 Thromboxanes, from arachidonic hydroperoxides, 612... 

Also dipropyl sulfoxide [LnBra (161)], diphenyl sulfoxide [Lnl3 (155)], tetramethylene sulfoxide [LnCl3 (162), LnBrs (163), Lnls (164)], and thioxane oxide [LnCl3 (166), LnBrs (163), Lnl3 (266)]. 

Hexafluorophosphate derivatives, such as [M(Me2SO)n][PF6]3 (M = La, Lu, Y), have been synthesized (365), and infrared data show O-bonding of the sulfoxide with ionic hexafluorophosphate groups. Analytical data are incomplete for this series, as decomposition, postulated to be to lanthanide fluorides, occurs. The (CH2)4SO complexes [M( CH2 4SO)t.5][PF6]3 are reported (145), which are 3 1 electrolytes with uncoordinated anions, implying a possible semibridged structure, as previously mentioned. Complexes of other cyclic sulfoxides, including thioxane oxide (146) and trans-1,4-dithiane-1,4-dioxide (147) derivatives of hexafluorophosphate salts have also been prepared. 

In addition to these systematic studies of lanthanide sulfoxide complexes, with variation in both sulfoxide and anion, other more isolated reports are available. Lanthanide isothiocyanate complexes of the cyclic sulfoxides thioxane oxide (490) and tetramethylene sulfoxide (493) have been synthesized and complexes of the unusual potentially chelating ligand 2-(ethylsulfinyl)pyridine-V-oxide (63) described. Detailed studies of the solvation of lanthanide-shift reagents by Me2SO have also appeared (178,179). 

Adducts of Ga and In perchlorates with tetramethylene sulphoxide, M(C104)3,6TMS0, and of Ga perchlorate with thioxan oxide, Ga(C104)3,6TS0, have been prepared and characterized.527 A considerable shift of i>(S=0) to lower wavenumber indicated co-ordination via the sulphoxide oxygen. 

Other sulfoxides that have been studied recently include thioxane oxide (Vincentini and Vieira, 1973 Vincentini and Perrier, 1974 Serra et al., 1976), tetramethylenesulfoxide (Bertan and Madan, 1972 Vicentini and Zinner, 1975), and trans-l,4-dithiane-1,4-dioxide (Vicentini et al., 1975). The results that have been obtained follow the same general patterns previously discussed. 

Oxidation of 1,4-thioxane by BTSP and f-butyl(trimethylsilyl) peroxide in CHCI3 at 25 °C is compared to those of the same substrate by the more common oxidants, f-butyl hydroperoxide and di-f-butyl peroxide, in the same solvent. The two silyl peroxides give similar oxidations rates, which are over 50 times higher than that measured for f-BuOOH, while f-Bu202 is almost unreactive under the conditions adopted. Oxidation... 

TABLE 14. Oxidation rates of thioxane and Af,Af-dimethyl- ci-anisidine by silyl peroxides as compared to analogous carbon peroxide... 

Table I. Comparison of the Relative Rate Constants for S -Oxidation of Thioxane by Hydroperoxides...

Dankleft et al. (37) have proposed that the S-oxidation of sulfide by hydroperoxides requires the presence of a proton source. Their conclusions were based on the finding that in the aprotic solvent dioxane the S-oxidation of thioxane is second order in alkyl peroxides. The mechanism suggested by them is shown in Equation 41. The... 

S-oxidation of thioxane by 4a-FlEtOOH in anhydrous dioxane is first order in the flavin hydroperoxide (35). Apparently the oxygen atom transfer potential of 4a-FlEtOOH is such that general-acid-catalyzed assistance of oxygen transfer is not required. 

A number of catalytic reactions studied by Russian authors are necessarily left out of this review. These include nitration and sulfona-tion (138). As an example the use of alumina in the synthesis of heterocyclic compounds may be mentioned. Ethylene oxide with ammonia gave pyridine with hydrogen sulfide about 20 % thiophene was formed at 300-450° (211). At 200°C. ethylene oxide and hydrogen sulfide gave thioxane and dithiane (212,429). Yur ev developed conditions under which the hetero atom of furan, thiophene, and pyrrole could be interchanged (425,426,427,428). 

NHs and H2S also undergo addition to ethylene oxide in the presence of NaX, but the initial addition products rapidly condense to produce heterocyclic molecules. At 340°, ethylene oxide and NHs produced piperazine, morpholine, and p-dioxane. Byproducts included ethylene and acetaldehyde, the latter arising from an isomerization reaction. HsS reacts with ethylene oxide at 200° to produce p-dithiane, p-thioxane, and p-dioxane, along with byproduct acetaldehyde. These transformations are summarized in the accompanying diagram. 

C4H6CI2OS, trans-2,3-Dichloro-1,4-thioxane, 32B, 199 C4H7NO5S, cis-5-Methyl-trans-5-nitro-1,3,2-dioxathian-2-oxide, 46B, 420... 

Benzyne intermediates are probably involved in the ring-closure of 2-(or 3-) chloro-2 -(methylthio)benzophenones to thioxanthones. Xanthones were prepared analogously. Syntheses of several pharmacologically useful thioxan-thene derivatives have been described. Ceric ammonium nitrate oxidizes thioxanthene to thioxanthone. ... 

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