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The first catalytic asymmetric thioacetalization of salicylaldehyde and dithiol is reported.

A series of 1,3-dithiol-2-one derivatives via [4 + 2] Diels–Alder cycloaddition reaction of 4,5-bis(dibromomethyl)-1,3-dithiol-2-one with vinyl-substituted compounds have been synthesized. Structures of all the newly synthesized compounds are well supported by spectral data such as 1H-NMR, MS, and elemental analysis. The structures of IVf and IVg have been analyzed by X-ray crystallography.

An efficient one-pot procedure has been developed for the synthesis of bis-1,5,3-dithiazepanes by reaction of ethane-1,2-dithiol with formaldehyde and ammonium salts. According to the X-ray diffraction data, the heterorings in 3,3′-[ethane-1,2-diylbis(sulfanediylmethanediyl)]bis(1,5,3-dithiazepane) in crystal adopt a chair conformation with axial orientation of the substituent on the nitrogen atom.

MeONa-mediated addition of dithiol (II) to alkynes (I) is accompanied by an intramolecular cyclization to afford spiro compounds (III), which can be regarded as partly modified furanose derivatives.

The reaction of 3H-1,2-dithiol-3-ones of type (I), (IV), and (VII) with isonitriles yields the corresponding 2-iminothiophen-3(2H)-ones.

The corrosion rate of copper powders in moist air obeyed a parabolic law. The rate constant was influenced by temperature, humidity, surface structures of the powders and production method. Surface treatment was carried out with triazine dithiol in different solvents and with hydrazine. The amounts of absorbed triazine dithiols on the powders and the adsorption rate was influenced by temperature, time, solvents, concentration, the kinds of triazine dithiols and the amounts of oxides. The corrosion rate decreased on introducing triazine dithiol films with water repellency and insulation of the copper powders.

Disulfide-containing peptides may be obtained in good yields and purities when oxidations are carried out on peptide chains anchored to polymeric supports used for solid-phase synthesis. Such approaches take advantage of the pseudo-dilution phenomenon which favors intramolecular processes. A variety of procedures have been demonstrated using the related model peptides Ac-Cys-Pro-D Val-Cys-NH2 and Ac-Pen-Pro-D Val-Cys-NH2 (which both readily assume a type II beta-turn conformation that becomes stabilized by a 14-membered disulfide-containing intramolecular ring), and oxytocin (conformationally mobile 20-membered disulfide ring). Both Boc and Fmoc were used for N alpha-amino protection, the beta-thiols of cysteine or penicillamine were blocked by S-acetamidomethyl (Acm), S-9-fluorenylmethyl (Fm), or S-trityl (Trt), and compatible anchoring linkages included HF-labile 4-methylbenzhydrylamide (MBHA), TFA-labile tris (alkoxy)benzylamide (PAL), and photolabile o-nitrobenzylamide (Nonb). Assemblies of linear sequences proceeded smoothly, and polymer-supported oxidations were carried out in a variety of ways either directly or after deblocking to the resin-bound dithiol. Chains were released from the support without substantial damage to the disulfide bridges, and overall yields were as high as 60-90%.

The cyclic disulfides 2,3-dithiabicyclo[2.2.2]oct-5-ene 5, 1,4-dihydro-2,3-benzodithiin 6 and hexa-hydro-5,8-epoxy-2,3-benzodithiin 7 have been prepared by oxidation of the corresponding dithiols. Each of these compounds has been subjected to vapour phase pyrolysis in order to determine whether a retro Diels–Alder reaction occurs, leading to the formation of diatomic sulfur (S2) and a diene. Compounds 5 and 7 both appeared to decompose in this way; in each case the expected diene was detected in the pyrolysate together with sulfur (S8). Attempts to intercept S2 and thus to obtain direct evidence for its formation were not successful. The benzodithiin 6 underwent an analogous loss of sulfur on vapour phase pyrolysis, but only as a minor reaction pathway, and this decomposition pathway was not detectable in solution pyrolyses. Solution pyrolysis of 6 in the presence of N-phenylmaleimide gave N-phenyl-2,3-naphthalimide 21 in low yield. cis-Cyclopentene-3,5-dithiol 9 has also been prepared but no evidence could be obtained for the formation of the disulfide 4 on oxidation. Reaction of the dithiol 9 with aldehydes and ketones in the presence of acids led to the formation of adducts (such as 12 and 13 from acetone) which were rapidly interconverted in acidic media.

Diathia [3] metacyclo [3]--(2,3)-, -(2,4)-, -(2,5)-, and -(3,4) thiophenophanes were prepared by dithiol bis-alkylations and were oxidized with m-chloroperbenzoic acid to the corresponding tetraoxides. Pyrolysis of the tetraoxides under a reduced pressure gave the corresponding [2] metacyclo [2] thiophenophanes together with many unexpected compounds. The conformations of the obtained products are also discussed

The synthesis and properties of the title electron donors which are tetrathiafulvalene (TTF) or bis(ethylenedithio)TTF (BEDT–TTF) analogues with a quinoid structure are described; the crystal structure of a derivative is also presented.

2-Dimethoxyphosphoryl-5,6-dihydro-1,3-dithiolo[4,5-b][1,4]-2-dithiin (8) and 2-triphenylphosphonio-5,6-dihydro-1,3-dithiolo[4,5-b][1,4]dithiin tetrafluoroborate (9) have been obtained in four steps from 4,5-ethylenedithio-1,3-dithiole-2-thione (4) (ca. 75% overall yield). Deprotonation of (8) and (9) yields the corresponding carbanion (10) and ylide (11) which have been trapped in good yield with glyoxal, cyclopentanone and anthraquinone to afford ethylenedithio-1,3-dithiafulvalenes

Sulfur extraction from the tripeptide thiol, glutathione (α-glu-cys-gly) (1) via reaction with syn-(1-bromo-ethyl, methyl)bimane (2) yields glutathione slfide and the thiabridged bimane, μ(S)-syn-(methylmethylene, methyl)bimane (3) [1]. The reaction with 2 has been extended to dithiols as models for important biological thiols such as reduced trypanothione. The fluorescent dithiols were derived through reductive cleavage with triphenylphosphine (tetrahydrofuan, Hcl−Kbr solution, pH 1.5) of the dithiatriclic bimane esters, μ(O2C(CH2)SS(CH2)nCO2)-syn-(CH2,CH3)B, n = 1, 2, 3, prepared from syn-(bromomethyl, methyl)bimane (4) and the corresponding dithiadicarboxylic acids. Sulfur extraction led to 3 and the cyclic sulfide derived from the dithiol in moderate yields. The dithiols, dithiothreitol and dithioerythritol, also yielded moderate amounts of 3. Sterically hindered thiols (e.g., those in hemoglobin) gave 3 in lower yields. Treatment of human red blood cells and red cells membranes (hemoglobin-free ghosts) with 2 gave rise to some 3. A side product in some reactions was the oxabridged bimane, μ(O)-syn-(methylmethylene, methyl)bimane.

The synthesis and properties of the unsymmetrical tetrathiafulvalenes condensed with 1,3-dithiol-2-ylidene moieties are described; the electrical properties of several cation radical salts are also presented.

O-Alka-2,4-dienyl S-(alk-2-ynyl or alk-2-enyl) dithiocarbonates (xanthates) underwent [3,3]sigmatropic rearrangement to give the dithiol esters which, on heating, extruded carbon oxysulfide (COS) to give the allylically rearranged sulfides which then underwent intramolecular Diels–Alder cycloaddition to give hydrobenzo[c]thiophenes. Lewis acids catalysed the extrusion and intramolecular cycloaddition reactions, in which the reactivity and endo-selectivity were remarkably enhanced. The structures of the cycloadducts were determined on the basis of the X-ray structure of a hydrobenzo[c]thiophene.Based on these findings together with MO calculation data, the observed reaction behaviours are discussed in terms of frontier molecular orbital considerations.

Synthesis of the title compound (1), and its molecular structure determined by X-ray crystallographic analysis, and electrochemical property investigated by cyclic voltammetry are described. Several cation radical salts of 1 have been prepared by electrochemical oxidation method, and their electrical properties are also presented.

The synthesis and properties of 2-(3,4-dicyanocyclopenta-2,4-dienylidene)-1,3-dithiole 2have been, previously reported. NMR spectral data of that compound imply a large contribution of the dipolar form to its electronic structure. Two-solvent diffusion recrystallization, in the presence of O2, yields the title compound 3, the crystal structure of which is reported here. This appears to be the first crystal structure of a compound containing the dicyanocyclopentadiene moiety. The space group is P1–, and the lattice parameters are a= 8.3617(19), b= 11.1196(23). c= 12.8159(20)A, α= 96.587(15)°, β= 103.103(15)°, γ= 109.917(16)° and V= 1066.9(4)A°3 for Z= 2. We also discuss a plausible mechanism for the formation of compound 3, and its spectral properties.

DIBALH reduction of the methyl ester group of 2-(thi)oxo-1.3-dithioles 1a and 1b selectively affords the corresponding alcohols 3a and 3b which are readily converted into the title compounds 6a and 6b under standard conditions; the latter behave as useful Wittig reagents leading to sulfur-rich and space-extended TTF derivatives.

Only one pair of reversible waves involving a net four-electron transfer has been observed in the redox process of pentakis(1,3-benzodithiol-2-ylidene)cyclopentane (1a), a potent electron-donating molecule. This is the first case of a single-wave four-electron transfer with only one macroscopic redox site in organic redox systems. Normal explicit difference digital simulation analysis assuming Nernstian response has been carried out to elucidate the detailed redox process of 1a. Our studies have shown that 1a mainly follows a two-step two-electron transfer and is converted to the tetracation (1a 4+ ) via the dication (1a 4+ ). The estimated redox potentials for the 1a/1a 2+ and 1a 2+ /1a 4+ couples are 0.394±0.003 and 0.386±0.003 V vs SCE, respectively

The optimum conditions for the preparation of N-acetyl-S-nitrosopenicillamine (SNAP)3 were determined and applied to the synthesis of the corresponding N-formyl compound 7. The nitrosation of penicillamine dipeptides was investigated and bis-thionitroso compounds 13, 18, 26 and 27 were isolated. S, S′-Dinitroso dithiol 13 showed biological activity akin to that of glyceryl trinitrate in decreasing systemic arterial blood pressure in anaesthetized rats and rabbits. Concomitant inhibition of collagen- or ADP-induced platelet aggregation was observed.

The title 1,3-dithiole compounds which were synthesized using a Wittig-Hornor reaction have a planar structure with both inter- and intramolecular short S···S contacts. Their electrochemical oxidation gave polythiophene derivatives which have lower oxidation potentials than polythiophene and the conductivity of the nonsubstituted derivative was 3.5 × 10−3 S cm−1.

The title compounds (2) were synthesized as the donor components for organic conductors, and preparation and electrical properties of their cation radical salts were investigated. Among various cation radical salts obtained so far, AsF6 salt of ethylenedithio-2 and SbF6 salt of ethylenedioxy-2 showed metallic temperature dependence of conductivities down to 0.6 K.

The title compounds were prepared and their electrochemical properties were investigated. Several cation radical salts composed of them showed metallic conductive behavior down to 0.6 K. The X-ray crystal structure of AsF6 salt of ethylenedithio derivative, (EOET-TTP)3AsF6, revealed that the donors have “κ-type” arrangement in the conducting sheet.

Bis(dithiolylidene)dihydrothiophene and its unsymmetrically substituted bis(alkylthio) derivatives, giving stable radical cations and dications on two-step one-electron oxidations, have been efficiently synthesized by convenient methods and electrical properties of their conductive complexes are described.

Crown thioethers, 1,4,8,11-tetrathiacyclotetradecanes and 1,4,8,11,15,18-hexathiaheneicosanes, have been synthesized as 2:2 and 3:3 cycloadducts in a ‘one-pot’ homolytic macrocyclization of alkynes with propane-1,3-dithiol.

The title compounds are strong electron donors and the parent compound whose structure is revealed by X-ray structural analysis gives a highly conducting charge-transfer complex with tetracyanoquinodimethane (TCNQ).

Preparation, crystal structure and electrical properties of the title compounds 1a–g are described; these donors gave several conducting salts showing metallic temperature dependence.

The title compound (1a) and its related unsymmetrical derivatives were prepared as new donors for organic conductors, and electrochemical properties and crystal structure of 1a were investigated. Several charge-transfer complexes and cation radical salts using them showed metallic temperature dependence of conductivity down to ca. 100 K.

Synthetically useful 1,3-dithiol-2-ylphosphonate esters (3) can be prepared in one step, and in good yield (up to 75%), from the corresponding 1,3-dithiole-2-thiones (1), simply by heating in the presence of a trialkyl phosphite at high dilution