Dithiete 1-oxide

Oxidation of the dithiete 175 with MCPBA (1 equiv.) yielded the dithiete 1-oxide 202 which, when heated in refluxing toluene, formed a mixture of the ring-opened product sulflne 203 (blue, A ax 576 nm) and 202 in the ratio 7 1 (95TL8583). Further oxidation of 202 or oxidation of 175 with... 

Dicyano-l,2-dithiete [53562-16-6] (14) is thought to be an intermediate when BAhr s Salt is oxidi2ed (64,65). If the oxidation is carried out in the presence of vinyl ethers, dihydro dithiins can be obtained in yields up to 60%. 

All unexpected reaction is the formation of dithiete 175, thiirene 1-oxide 185, and thioketone 186 by the treatment of di-l-adamantylacetylene with S2CI2 (99UPl).Tlie yield of each compound is 30% at most. 

As already described, oxidation of sodium mercaptomaleiioiiitrile (146) formed the dithiete 145, though it was not isolable (62JA4746, 62JA4756, 62JA4772). Decomposition of the trithiole 256 in DME at room temperature also produced 145, which dimerized to yield 257 as the hnal product or was trapped by ethyl vinyl ether to give 258 (62JA4772). 

Tile preparation of beiizo-l,2-dithiete (264) had been claimed by oxidation of 1,2-benzenedithiol (25JIC318). However, later work has shown that the reaction product was probably a polymeric mixture (61JOC4782). Subsequently, compound 265 was irradiated to give a mixture of CO, sulfur, and dithiin and thiophene derivatives, which could, at least in part, be explained by the formation of 266 (72JHC707). Results of the thermolysis of 267 were also rationalized in terms of the intermediacy of o-dithiobenzo-quinone (the tautomer of 264) (78JOC2084). 

Thermolysis of the dicarbamic acid silyl ester (CH2 N[SiMe3]C02SiMe3)2) gives the 1,3-diazetane derivative 26 <96JOM93>. Alkylation of the 1,3-dithietane tetraoxide 27 with a,co-dihaloalkanes yields the dispiro compounds 28 (n = 1-4) <95ZOR589>. The first 1,2-dithiete S-oxide 29 is reported <95TL8583>. 

The oxidation of 3,4-di(l-adamantyl)-l,2-dithiete 116a and 3,4 - d i -ft rft b u t y 1 -1,2 - d i t h i c t c 116b as well as 3, 3, 7, 7 -tetramethylcyclohepteno[l, 2 -r ]-l,2-dithiete 116c was investigated. It was found that w-chloropcrbcnzoic acid (MCPBA) oxidation of 1,2-dithietes 116 with 1 equiv of the oxidant afforded the corresponding 1,2-dithiete. 9-oxides 117, while oxidation with an excess (2-3 equiv) of this oxidant produced a mixture of isomeric (EE-, EZ-, and ZZ-) bis-sulfines 119 via the corresponding 1,2-dithiete Ah -dioxide intermediates 118 (Scheme 13). The oxidation... 

Dithiete can be used as an oxidant for the thiometalates and oxythiometalates, and thus induced internal electron-transfer reactions provide an efficient method for synthesizing selected metal dithiolene and oxo-containing... 

The synthesis of 1,2-dithietes was extensively described by Zoller in CHEC-II(1996) <19%GHEC-II(1B)1113>, and the literature until 1995 was summarized. Since that time, a few interesting procedures have been reported. The oxidation of the titanium complex 224 with sulfuryl chloride in benzene gave 3,4-dimethoxycarbonyl-l,2-dithiete 225 in 66% yield. Macrocyclic compounds 226 and 227 were isolated as by-products (Equation 46) <1998JOC8192, 1999PS431>. 

The reaction of 1,2-diadamantylacetylene with disulfur dichloride led to the formation of the dithiete 232 (mentioned above), l,2-diadamantyl-2-thiooxoethanone 233, and the thiirene 1-oxide derivative 234 in 21%, 33%, and 27% yield, respectively (Equation 50) <2000TL8349, 2003JA12114, 1998BCJ1181 >. 

The dithiete isomers of bis(thioketones) have been oxidised [112] to afford the first a-bis(sulfines), fully characterised by X-ray analysis. The major isomers have an (E,E) structure. For the monoxidation, a dithiete monoxide was evidenced and shown to equilibrate with the a-thioxo sulfi-ne. These results confirm that oxidation of the C=S moiety stabilises this weak 2p-p double bond. 

Figure 1. Valence bond description of the various dithiolene ligand forms. Two-electron oxidation of the dianionic ene-1,2-dithiolate results in the formation of the 1,2-dithione and 1,2-dithiete resonance forms.

Oxidation of complex Cp2Ti(S2C2Z2) (Z = C02Me) with sulfuryl chloride affords 1,2-dithiete and its oligomers (132). The reaction, if proved general, could be employed as a synthetic route to dithietes (Eq. 29). 

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