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The synthesis of six 2,6-di(pyrazol-1-yl)pyridine derivatives bearing dithiolane or carboxylic acid tether groups is described: [2,6-di(pyrazol-1-yl)pyrid-4-yl]methyl (R)-lipoate (L1), 2-[(2,6-di(pyrazol-1-yl)pyridine)-4-carboxamido]ethyl (R)-lipoate (L2), 2-[(2,6-di(pyrazol-1-yl)pyridine)-4-carboxy]ethyl (R)-lipoate (L3), N-([2,6-di(pyrazol-1-yl)pyrid-4-ylsulfanyl]-2-aminoethyl (R)-lipoamide (L4), 2-[(2,6-di(pyrazol-1-yl)pyridine)-4-carboxamido]acetic acid (L5) and 2-[(2,6-di(pyrazol-1-yl)pyridine)-4-carboxamido]propionic acid (L6). The iron(ii) perchlorate complexes of all the new ligands exhibit gradual thermal spin-crossover (SCO) in the solid state above room temperature, except L4 whose complex remains predominantly high-spin. Crystalline [Fe(L6)2][ClO4]2·2MeCN contains three unique cation sites which alternate within hydrogen-bonded chains, and undergo gradual SCO at different temperatures upon warming. The SCO midpoint temperature (T1/2) of the complexes in CD3CN solution ranges between 208-274 K, depending on the functional group linking the tether groups to the pyridyl ring. This could be useful for predicting how these complexes might behave when deposited on gold or silica surfaces.

A new series of substituted anthranilic esters derivatives linked with a 1,3-dithiolane andbenzyloximino moiety was synthesized using the simple esterfication reaction and products werefully characterized. The isolated yields of these compounds range from 59 to 96%. 1,3-dithiolane ester and the benzyloxy substituted diamine derivatives are white solids and stable toair and moisture. The synthesized compounds can be exhibits UV-vis absorption properties bytheir structures with a amine or amide group, It is observed that absorption maximum is excellentfor 2,6-disubstituted benzyloxy esters which can be explained by electron transfer or conjugationis steric effect in ortho substitution from the amino group and the amide group.

A mechanism has been proposed for the reaction of 1,3-dichloropropene with ethane-1,2-dithiol in the system hydrazine hydrate–potassium hydroxide on the basis of DFT quantum chemical calculations [B3LYP/6-311++G(d,p)]. The proposed mechanism involves several consecutive steps, in particular nucleophilic substitution of chlorine at the sp3-hybridized carbon atom by sulfur, prototropic allylic rearrangement of the monosubstitution product with double bond migration toward the sulfur atom, dithiolane ring closure via nucleophilic attack of the second thiolate group on the carbon atom in the γ-position with respect to the second chlorine atom, and prototropic allylic rearrangement of 2-vinyl-1,3-dithiolane to more stable 2-ethylidene-1,3-dithiolane.

Dodecanoyl isothiocyanate 1 was utilized for the construction of thioureido, 2-thioxo-2,3-dihydroquinazolin-4(1H)-one, benzo[d]-1,3-thiazin-4(H)-one and 3-amino quinazolin-4(3H)-one derivatives 2, 3, 4, and 5 respectively. However, N′-(2-cyanoacetyl) dodecanehydrazide 6 was also used as a key starting material for the construction of a variety of new pyrazolone, pyrazole, thiadiazole, pyridazine, chromeno[2,3-c]pyrazole, and dithiolane derivatives 7, 9, 12, 15, 18, and 20, respectively. The newly synthesized compounds were characterized by elemental analyses and spectral data (IR, 1H NMR, and mass spectra). Some of the newly synthesized compounds bearing heterocyclic moieties were tested for antioxidant activity as reflected in their ability to inhibit oxidation in rat brain and kidney homogenates using 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) inhibition. Also, in vitro anticancer activity was examined using the standard (3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide) (M...

The synthesis and characterization of novel sulfur-containing terpyridine ligands and their ruthenium and rhodium complexes [Ru(tpy)2](PF6)2, [Rh(tpy)2](PF6)3, [Ru(phen)(tpy)Cl](PF6), [Rh(phen)(tpy)](PF6)2 (phen = phenanthroline; tpy = S-[4-(2,2:6′,2″-terpyridin-4′-yl)phenoxy]butyl ethanethioate or 4′-[4-(1,2-dithiolane-3-yl)butylcarboxy)phenyl]-2,2′:6′,2″-terpyridine) have been described. The complexes are redox-active, showing both metal-centered and ligand-centered processes. The data of electrochemical study confirm the chemisorption of complexes on the gold electrode surface. The antibacterial activity of the synthesized complexes was tested against two pathogens (Micrococcus luteus and Pseudomonas aeruginosa) by the well diffusion method. A biological study indicated that two complexes exhibit a good activity against M. luteus and the activity of symmetrical ruthenium complex [Ru(tpy-C4H4-O-C(O)-(CH2)4-C3H5S2)2](PF6)2 is better than the activity of the commercially available antibiotics streptomycin and kanamycin. It was shown that the ruthenium terpyridine–phenanthroline complex [Ru(phen)(Tpy-C6H4-O-(CH2)4-SCOCH3)Cl]PF6 efficiently catalyzed the oxidation of triphenylphosphine to triphenylphosphine oxide and styrene to styrene oxide with iodosobenzene in mild conditions.

Differently substituted 4-(1,3-dithiolan-2-ylidene)but-1-ynes were conveniently converted into the corresponding thiophenes and dihydrothiophenes in good to high yields under mild conditions. 1,3-Dithiolan-2-ylidene acted as a masked thiolate anion and underwent tandem fragmentation and 5-exo-dig annulation with an alkyne moiety to form the five-membered sulfur heterocycles.

The preparation and characterization of the three ferrocene based dithiolane complexes [ ( η 5 - C 5 H 5 ) F e ( η 5 - C 5 H 4 ) NHC ( O ) ( CH 2 ) 4 CHS 2 CH 2 CH 2 ¯ ] 1, [ ( η 5 - C 5 H 5 ) Fe ( η 5 - C 5 H 4 ) CH 2 OC ( O ) ( CH 2 ) 4 CHS 2 CH 2 CH 2 ¯ ] 2 and [ ( η 5 - C 5 H 5 ) Fe ( η 5 - C 5 H 4 ) NHC ( O ) ( CH 2 ) CHS 2 CH 2 CH 2 ¯ ] 3, with different spacer groups between the ferrocenyl moiety and the dithiolane unit, are reported. The complexation of 1 and 2, using the oxidative addition of the S–S bonds to Pt(0), is also described, leading to the square planar Pt(II) complexes [Pt(PPh3)2(S2CH2CH2CH-κ2-S,S)(CH2)4C(O)NH(η5-C5H4)Fe(η5-C5H5)] 4 and [Pt(PPh3)2(S2CH2CH2CH-κ2-S,S)(CH2)4C(O)OCH2(η5-C5H4)Fe(η5-C5H5)] 5, respectively. The reduction of the S–S bond in 1 and 2 yields the corresponding dithiols; these can be deprotonated and treated with ClSiMe3 to prepare [(η5-C5H5)Fe(η5-C5H4)NHC(O)(CH2)4CH(SSiMe3)CH2CH2(SSiMe3)] 7 and [(η5-C5H5)Fe(η5-C5H4)CH2OC(O)(CH2)4CH(SSiMe3)CH2CH2(SSiMe3)] 9, respectively. The complexes were characterized via NMR and UV–Vis absorption spectroscopy, cyclic voltammetry and single crystal X-ray diffraction for 1 and 4.

Ethylene trithiocarbonate reacted with dimethyl acetylenedicarboxylate to furnish tetramethyl thiopyran-4-spiro-2′-(1,3-dithiolane)-2,3,5,6-tetracarboxylate, a new thiopyran-4-spiro-2′-(1,3-dithiolane) heterocyclic compound, as the minor product together with the major product dimethyl 2-thioxo-1,3-dithiole-4,5-dicarboxylate. The new heterocycle was probably formed through a [2 + 2] cycloaddition between ethylene trithiocarbonate and dimethyl acetylenedicarboxylate followed by a 1,3-dipolar cycloaddition or [4 + 2] cycloaddition. Crystal structure of the new compound revealed that the thiopyran ring and 1,3-dithiolane moiety were perpendicular to each other.

Two methoxycarbonyl-substituted 2,5-di(1,3-dithiol-2-ylidene)-1,3-dithiolane-4-thione derivatives with alkylsulfanyl groups of different sizes were synthesized, and their redox and electronic prope...

Four bromine-substituted 2,5-di(1,3-dithiol-2-ylidene)-1,3-dithiolane-4-thione derivatives, 1a, 1b, 1c, and 1d, were synthesized, and their physical properties were investigated. These compounds we...

The reaction of 1-(4-tolylthio)-, 1,1-bis(4-tolylthio)-, or 1,1,3-tris(4-tolylthio)perchloro-2-nitro- 1,3-butadiene with α,β-bifunctionalized ethanes such as N,N-, N,O,-, N,S-, O,S-, S,S-, or O,O- bisnucleophiles leads to both, highly functionalized 2-(1-nitroallylidene) derivatives of imidazolidine, oxazolidine, thiazolidine, (1,3)oxathiolane, or (1,3)dithiolane, respectively, and to the open chain, next higher thiolated buta-1,3-diene. The product distribution is highly sensitive to modifications of the reaction conditions: apart from changes of molar ratios of substrates and reagents the reaction temperature plays an important role. Thus, increase of the reaction temperature favours formation of the 1,3-heterocyclic ring. In all cases, extensive spectroscopic investigations have been performed and, in the case of the (1,3)oxathiolane also an X-ray analysis.

Nucleophilic additions of enolates, piperidine and methanol to easily prepared alkylidene[l,3]dithiolane-l,3-dioxides afforded the respective adducts with good yields. Selectivities were strongly dependant from the steric hindrance of the substrate and reached 92:8 to ≥ 98:2 in additions to the phenyl-substituted bissulfoxide product.

4-Methyl-3,4-dihydro-2H-1,4-benzoxazin-3-one 1 reacted with CS 2 and halo compounds to give thieno-1,4-benzoxazines 2a , b and 2-(1,3-dithiol-2-yliden)-1,4-benzoxazines 3a , b , respectively. Reaction of compound 1 with cyanoketene S,S diacetal afforded pyrano-1,4-benzoxazine derivatives 4 , 5 . Treatment of compound 1 with bromine in 1:2 molar ratio afforded 2,2-dibromo derivative 6 . Compound 6 reacted with bidentates, or with CS 2 and reactive methylenes to give the corresponding spiro compounds 7a–f and 8a–d , respectively. 2-(2-Bromo-4-methyl-3,4-dihydro-2H-1,4-benzoxazin-3-yliden)malononitrile 10 was allowed to react with ethyl thioglycolate, aniline or benzylamine to yield thiopyrano-1,4-benzoxazine 11 or pyrrolo-1,4-benzoxazines 12a , b , respectively. 2-(1-Ethoxy-methyliden)-4-methyl-3,4-dihydro-2H-1,4-benzoxazin-3-one 13 reacted with CS 2 and reactive methylenes or malononitrile to give spiro dithiolane 14a–c and 2-(4-methyl-3-oxo–3,4-dihydro-2H-1,4-benzoxazin-2-ylidenmethyl)malononitri...

The selective formation of optically active 2-acyl-2-alkyl-1,3-dithiolane 1,1-dioxides from the corresponding 2-acyl-2-alkyl-1,3-dithiolane 1-oxides, by reaction with OsO4 and NMO in acetone, is reported. These compounds underwent stereoselective reactions at the carbonyl group of the acyl group with organometallic reagents. These reactions were completely regioselective, and no attack at either of the S-atoms was observed, unlike similar reactions with the corresponding sulfoxides. The nature of the metal atom had a direct effect upon the configuration of the product alcohols.

The reaction of 2-alkoxypropenals with ethane-1,2-dithiols and propane-1,3-dithiols under various conditions was studied by 1H NMR and chromato-mass spectrometry. Under kinetically controlled conditions at 20° in the absence of catalysts the addition of dithiols takes place according to the Markovnikov rule. The primary adducts are unstable and are quickly converted into the corresponding substituted 1,4-dithiacycloheptane or 1,4-dithiane. The latter in turn can be converted under the reaction conditions or at high temperature into a thiolane derivative. The reaction of 2-ethoxypropenal with a twofold excess of ethane-1,2-dithiol at 60°C in the presence of p-toluenesulfonic acid leads to 2-methyl-2,2'-bi(dithiolane)

Differently substituted 4-(1,3-dithiolan-2-ylidene)but-1-ynes were conveniently converted into the corresponding thiophenes and dihydrothiophenes in good to high yields under mild conditions. 1,3-Dithiolan-2-ylidene acted as a masked thiolate anion and underwent tandem fragmentation and 5-exo-dig annulation with an alkyne moiety to form the five-membered sulfur heterocycles.

3,4-Diamino-2,5-dicarbethoxythieno(2.3-b)thiophene 1 reacted with malononitrile or ethyl cyanoacetate to afford bis(thienopyrimidin-4-one) derivatives 2a.b The reaction of compound 1 with o-aminothiophenol, o-aminophenol or o-phenylenediamine gave benzothiazolyl-, benzoxazolyl-, benzoimidazolylthienothiophene 3a-c, Chloroacetylation of compound 1 and reacting the resulting compound 4 with malononitrile furnished thienopyrolopyrimidine 6. Fusion of compound 1 with formamide yielded bis(thienopyrimidine) 7 which reacted with POCI3/PCl5 to yield the corresponding chloro derivative 8 which was converted into the corresponding hydrazine derivative 9. Treatment of compound 1 with CS2, NaOH and 1,2 dibromoethane produced the corresponding 1.3 dithiolane 11 which also treated with chloroacetyl chloride or ethyl mercaptoacetate to get the corresponding β-lactame 12 or thiazolidinone 13. On reacting compound 1 with CS2, NaOH and (CH3)2S04 produced the corresponding bi(dithiocarbamate methyl ester) 14 which...

Cyclopent-2-enones bearing a plane-nonsymmetric oxygen function on C-4 reacted efficiently with anions derived from aromatic ester dithioacetals to provide annulated products in a highly diastereoselective fashion. Whereas the anion of a dimethoxy aromatic ester dithiolane more rapidly reacted by an alternative intramolecular pathway, the anion of the corresponding aromatic ester dithiane was suitable for the intermolecular cyclization.

4-Alkyl-2-imino-1,3-dithiolanes and 4-alkyl-2-iminium-1,3-dithiolanes were prepared in excellent yields with complete regiospecificity under mild conditions by the iodocyclization of S-allyl dithiocarbamates. Dehydrohalogenation of the 4-alkyl-2-imino-1,3-dithiolanes gave 4-alkylidene-2-imino-1,3-dithiolanes in excellent yields.

Synthesis of the TTF (tetrathiafulvalene) donors with a 1,3-dioxolane, 1,3-dithiolane, or 1,3-oxathiolane ring ( 1–3 ) has been accomplished via the (MeO) 3 P-promoted cross-coupling reaction of the corresponding new ketones ( 6–8 ) and thiones ( 9a-c ). The radical-cation salts derived from 2a with AuI 2 − , BF 4 − , and AsF 6 − exhibited metallic conducting behavior for single crystals.

Nitrogen-containing five-membered heterocycles, N-methylpyrrole 2, N-methylpyrazole 4, N-methylimidazole 6, 4-methylthiazole 11, N-methylindole 14, benzothiazole 16, N-methylbenzimidazole 18, and benzoxazole 20 were lithiated with BuLi and LDA in THF and reacted with the polymerization-resistant 1,2-dithiolane 1. All of the corresponding lithioheterocycles cleaved the S–S bond of the 1,2-dithiolane 1 to give the ring-opened products in line with the carbanion mechanism proposed for the enzyme-reductive acylations of lipoic acid. The ring-opened products 8, 9, 13, 22, and 23 were isolated in good yields and high purity. The ring-opened products from benzothiazole and N-methylbenzimidazole were decomposed by the action of excess lithioheterocycles. The lithiobenzoxazole was less reactive than the other lithioheterocycles. © 1998 John Wiley & Sons, Inc. Heteroatom Chem 9:289–294, 1998

The reactions of metalated trans-1,3-dithiolane 1,3-dioxide (10) with aldehydes have been studied through variations in the metal counterion, reaction temperature, and aldehyde. High yields of addu...

We have the reaction of α-acyl-β-aminovinyl of the 8-azasteroid series with ethanedithiol. The occurrence and orientation of the reaction are determined by structural and steric factors. As applied to derivatives of 8-azasteroids of the D-homo series, the reaction is irreversible and consequently the dithioacetal derivatives of this series are easily hydrolysed under acid and base conditions. Desulfurization over Raney nickel of the 17-dithioacetal derivative of 8-azagona-12,17-dione occirs with simultaneous dehydrogenation of the C ring and leads to the 17-deoxo-9,11-dehydro, ehile desulfurization of the 1-dithioacetal of 8-aza-D-homogona-12,17-a-dione leads to the 12-deoxo derivative. By reaction of the 12-dithioacetal of 8-aza-D-homogona-17a-one with hydroxylamine, we obtained the 12-oximino derivative, which is the result of an unusual reaction at the site of the spiro coupling of the dithiolane ring with the 8-azasteroid ring.

Lithiated thiophenes 3 cleaved S[sbnd]S bond of 4,4-disubstituted 1,2-dithiolane 1 and naphthalene-1,8-disulfide 5 to give the ring opened products 2 and 6, respectively, in excellent yields.

Reaction of benzenethiol with the 1,3-dithiolane 1,3-dioxides 3a–f gave the 1,4-dithiane 1-oxides 4–5, the αβ-unsaturated sulfoxides 6–9, the ring-opening products 10–11 and various reduction products. Addition of benzenethiol, malononitrile, diethyl malonate or 2-mercapto-4,5-dihydrothiazole to the double bonds of the 2-alkenyl-1,3-dithiolane 1,3-dioxides 3g–h was performed with methylmagnesium chloride in methanol. Addition of methanol or an allyl group to the dioxide 3h occurred regioselectively to give the 1,3-dithiolane 1-oxide 19 or the 1,3-dithiolane 20.

Lithiated thiophenes 3 cleaved S[sbnd]S bond of 4,4-disubstituted 1,2-dithiolane 1 and naphthalene-1,8-disulfide 5 to give the ring opened products 2 and 6, respectively, in excellent yields.

The reactions of metalated trans-1,3-dithiolane 1,3-dioxide (10) with aldehydes have been studied through variations in the metal counterion, reaction temperature, and aldehyde. High yields of addu...

Nitrogen-containing five-membered heterocycles, N-methylpyrrole 2, N-methylpyrazole 4, N-methylimidazole 6, 4-methylthiazole 11, N-methylindole 14, benzothiazole 16, N-methylbenzimidazole 18, and benzoxazole 20 were lithiated with BuLi and LDA in THF and reacted with the polymerization-resistant 1,2-dithiolane 1. All of the corresponding lithioheterocycles cleaved the S–S bond of the 1,2-dithiolane 1 to give the ring-opened products in line with the carbanion mechanism proposed for the enzyme-reductive acylations of lipoic acid. The ring-opened products 8, 9, 13, 22, and 23 were isolated in good yields and high purity. The ring-opened products from benzothiazole and N-methylbenzimidazole were decomposed by the action of excess lithioheterocycles. The lithiobenzoxazole was less reactive than the other lithioheterocycles. © 1998 John Wiley & Sons, Inc. Heteroatom Chem 9:289–294, 1998

Synthesis of the TTF (tetrathiafulvalene) donors with a 1,3-dioxolane, 1,3-dithiolane, or 1,3-oxathiolane ring ( 1–3 ) has been accomplished via the (MeO) 3 P-promoted cross-coupling reaction of the corresponding new ketones ( 6–8 ) and thiones ( 9a-c ). The radical-cation salts derived from 2a with AuI 2 − , BF 4 − , and AsF 6 − exhibited metallic conducting behavior for single crystals.

The first palladium-catalyzed ring-expansion reaction of 2-vinylthiiranes with heterocumulenes to form sulfur-containing five-membered-ring heterocycles is described. This regioselective reaction requires 5 mol % of Pd2(dba)3·CHCl3 and 10 mol % of bidendate phosphine ligand (dppp, BINAP), at 50−80 °C, in THF. The reaction of 2-vinylthiiranes with carbodiimides, isocyanates, and ketenimines affords 1,3-thiazolidine derivatives, whereas the reaction with diphenylketene or isothiocyanates results in the formation of 1,3-oxathiolane or 1,3-dithiolane compounds in good to excellent isolated yields and in up to 78% ee.

1, 3 - Disubstituted- 4 - (1′, 3′- dithiolane /dithiane - 2′- ylidene) - 2 -pyrazolin-5-one derivatives like (1a–c), (2a–c), (3a–c) have been obtained by condensation of 2-pyrazolin-5-ones (1), (2) and (3) with carbon disulfide in presence of triethylamine followed by the reaction with 1,2-dibromoethane (4a), 1,3-dibromopropane (4b) and 1,3-dibromobutane (4c) respectively.

Reactions of 2-aryl-1,3-dithiolane-S-oxides 1 with MeMgl in refluxing benzene-ether furnish a useful procedure for introducing the isopropenyl group. The reaction may proceed via a fragmentation-coupling process leading to the alkylative olefination product.

Asymmetric oxidation of verbenone ethylene dithioacetal with m-chloroperoxybenzoic acid at different substrate-to-oxidant ratios in methylene chloride at −10°C gave previously unknown (1S,1′S,2S,3′S,5S)-4,6,6-trimethylspiro[bicyclo[3.1.1]hept-3-ene-2,2′-[1,3]dithiolane] 1′,3′-dioxide, (1S,2S,3′S,5S)-4,6,6-trimethylspiro[bicyclo[3.1.1]hept-3-ene-2,2′-[1,3]dithiolane] 1′,1′,3′-trioxide, and (1S,5S)-4,6,6-trimethylspiro[bicyclo-[3.1.1]hept-3-ene-2,2′-[1,3]dithiolane] 1′,1′,3′,3′-tetraoxide whose structure was determined by X-ray analysis.

4-Alkyl-2-imino-1,3-dithiolanes and 4-alkyl-2-iminium-1,3-dithiolanes were prepared in excellent yields with complete regiospecificity under mild conditions by the iodocyclization of S-allyl dithiocarbamates. Dehydrohalogenation of the 4-alkyl-2-imino-1,3-dithiolanes gave 4-alkylidene-2-imino-1,3-dithiolanes in excellent yields.

Publisher Summary New catalysts for the carboxylation of epoxides to afford 1,3-dioxolan-2-ones have been reported including the naturally occurring amino acids, zinc pyridine-2-carboxylate combined with N -methylimidazole, a rhenium complex anchored to an ionic liquid component, a polymer-supported imidazolium salt, and polyethyleneglycol end-capped with guanidinium salt functions. A patent describes the reaction of fullerene mono- and di-epoxides with ketones to give C 60 -fused dioxolanes and their use for solar cells. 1,3-Dioxolane formation is formed when the sesquiterpene lactone parthenin is treated under Baylis–Hillman conditions with aromatic aldehydes and affords products. The reaction of carbonyl compounds with ethanedithiol to give 2-substituted 1,3-dithiolanes can be achieved under solvent-free conditions using PhCH 2 PPh 3 + Br 3 – and the system is selective for aldehydes over ketones, while such functionalization of the carbonyl groups in polymeric aromatic ketones improves their solubility and aids characterization. A nuclear magnetic resonance (NMR) study of stereoelectronic effects in dithiolane sulfoxides has appeared and the new donor–acceptor system has been examined for possible use in solar cells.

Oxidation of sulfide 4 gave a mixture of cis and trans monosulfoxides 5 and 6 as major and minor products, respectively, plus a small amount of disulfoxides 7. The structural assignments of cis and trans sulfoxides 5 and 6 were based on 1H NMR spectroscopy and the regiospecific deuterations of the two isomers . Under neutral conditions cis sulfoxides 5 underwent a sigmatropic rearrangement with 2-methylene hydrogens to give sulfenic acids 18, followed by cyclization to dihydro-1,4-dithiins 2. The trans sulfoxides 6 rearranged involving 2-methyl hydrogens to form isomeric dihydrodithiins 3 via sulfenic acids 19. In the reactions of both the sulfoxides, sulfoxides 4 and disulfides 11 were also formed as minor side products. In the presence of acid catalyst cis sulfoxides 5 produced 2 in quantitative yields plus a small amount of 3 , while the trans sulfoxides 6 gave 2 as major product and 3 as minor. The mechanisms of formation of 2, 3, 4 and 11 are discussed.

The reaction of dipotassium 2-nitro-1,1-ethylenedithiolate 1 with propargyl bromide has provided isomeric 4-methylene-2-(1-nitroinethylidene)-1,3-dithiolane 4 and 4-methyl-2-(1-nitroincthylidene)-1,3-dithiole 6 via novel monoalkylation-cyclization.

Upon treatment with W(CO) 6 , dithioketals undergo desulfurdimerization to give the corresponding dimeric olefins in good to excellent yields. The mechanism of this newly discovered reaction has been investigated. Thioketones have been isolated from the reactions of highly crowded dithioketals. The mechanism for the formation of thioketones has been shown to occur via a new type of radical fragmentation process of dithiolane. Thermolysis of 2,2-dimethylindan-1-yl 2-thiophenoxyethyl sulfide in the presence of tert-butyl adamantane-1-peroxycarboxylate (a typical radical initiator) has been studied for comparison. Thioketones react with W(CO) 6 , giving dimeric olefins and/or undergoing carbene-like insertion reactions