1.2- Dithiin 1-oxides, dihydro

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%. 

Reactions of cyclopentadienyl- and (pentmethylcyclopentadienyl)iron dicarbonyl 2-alkynyl complexes as well as cyclopentadienylmolybdenum tricarbonyl 2-alkynyl complexes with 4,5-diphenyl-3,6-dihydro-l,2-dithiin 1-oxide 111 were shown to yield transition metal-substituted five-membered ring thiosulfinate esters 112 in moderate to excellent yields (Scheme 27) <19910M2936, 1989JA8268>. These reactions are formal [3-1-2] cycloadditions. When... 

Vinyl-3,6-dihydro-l,2-dithiin 2-oxide has been isolated as one of the main components from garlic Allium sativum) <2001MI867>. Its structure was elucidated by NMR and MS. 

Only a few examples of ring syntheses by transformation of another ring have been published, as exemplified by the preparation of the sultines 168 by ring enlargement of five-membeted thiolane 1-oxides 166 (cf Section 8.10.9.2.3) and the 3,6-dihydro-l,2-dithiins 202 by catalytic transformation of vinylthiiranes 201 (cf Section 8.10.9.4.2). Because possibilities to synthesize six-membered rings with oxygen and/or sulfur as heteroatoms in 1,2-positions are rather limited, these reactions have been covered already in Section 8.10.9 together with alternative syntheses from alicyclic compounds. 

Evidence of the existence of oxidation state +IV is not yet convincing. Some complexes with dithiolene or dithiolate systems have been reported, such as [Au(5,6-dihydro-l,4-dithiin-2,3-dithiolate)2] (Figure 1.76) [350], or [Au(2,3-dithiophe-nedithiolate)2] [351]. They were prepared by chemical or electrochemical oxidation of... 

A close structural relationship with I IF derivatives, especially BEDT-TTF, is exhibited by dddt metal complexes [dddt = 5,6-dihydro-1,4-dithiin-2,3-dithiolate (63)]. The most interesting feature of this dithiolene ligand is the ability of its metal complexes to form not only anionic salts like dmit, but also cationic salts like TTF derivatives [89], to afford non-stoichiometric IR salts of type [M(dddt)2]mX . Thus the cyclic voltam-mogram of [Bu4N][Ni(dddt)2], after its initial oxidation, exhibits the reduction of neutral [Ni(ddt)2]° to anion [Ni(ddt)2]" at 0 V, and its further reduction to the dianion [Ni(dddt)2]2 , as well as the oxidation of [Ni(dddt)2]° to the cation [Ni(dddt)2] + at 0.8 V (MeCN versus Ag/Ag/Cl). The feasible synthesis of conducting donor-acceptor complexes involving dddt metal derivatives as donors and dmit metal derivatives as acceptors has also been demonstrated [90]. 

It was found that the two compounds depicted in Fig. 8-15, i.e., l,l -bis[(5,6-dihydro-l,3-dithiolo[4,5-h][l,4]dithiin-2-ylidene)-methyl]ferrocene and l,l -bis[(l,3-benzodithiol-2-ylidene)methyl]ferrocene are very similar, as far as their redox behavior and CT complexes are concerned. Thus, they both display three subsequent oxidation processes, only the first two exhibiting features of chemical reversibility. Furthermore, they form 1 2 CT complexes with TCNQ that are electrically... 

An interesting feature concerning the redox properties of the complex, [Au(dddt)2] (dddt = 5,6-dihydro-l,4-dithiine-2,3-dithiolate, 3), is that the one-electron oxidized product, [Au(dddt)2]°, can be isolated14. An X-ray analysis of the neutral complex reveals a square planar gold structure stacked in dimeric units as a result of intermolecular S-----S contacts. Extended Hlickel calculations predict that the odd electron resides pri-... 

Acenaphthylene reacts with elemental sulfur in DMF at 120°C to give thiophene (Scheme 82) (415) when the reaction was quenched at the early stage, a dihydro-1,4-dithiin, which is a probable intermediate leading to (415), is isolated <89SUL135>. Acenaphthylene also reacts with an S " species, generated by oxidation of a carbon-sulfur electrode, to give (415) in a better yield <94BSF789>. 

Without additional reagents 2,3-Dihydro-l,4-dithiins from 1,3-dithiolane 1-oxides... 

Disulfuroxide (S=S 3) and disulfurdioxide (0=S=S=0) are unstable, and they polymerize to give polysulfur oxides. In disulfuroxide, the S=S bond is weaker and more polarized than the S=0 bond . Disulfur oxide is conveniently generated in the thermolysis of 4,5-diphenyl-3,6-dihydro-1,2-dithiin-l-oxide 2. ... 

The reaction of the disulphide C1C(E)=C(E)SSC(E)=C(E)SCN(E = COaMe) with sodium thiophenolate unexpectedly yielded the dithiin (18). Addition of sulphene or phenylsulphene to 3-aminovinyl-thiones afforded 1,2-dithiin 1,1-dioxides (see Vol. 3, p. 238) or their dihydro-derivatives. Oxidation of 1-thiochromene with selenium dioxide yielded the novel heterocycle (19). 

Photochemically generated diatomic sulphur added to l,2-bis(methylene)-cyclohexane to afford a 3,6-dihydro-l,2-dithiin. The dihydrodithiin (20) was formed by thermal rearrangement of a 1,3-dithiin. Addition of disulphur monoxide to 2,3-disubstituted buta-1,3-dienes yielded the rather unstable dihydrodithiin 1-oxides (21). 

---