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A novel fluorescent probe molecule, 2-(anthracen-9-yl)-1,3-dithiolane (AADT), is designed and synthesized for Hg2+ detection successfully, based on a good aggregation induced emission (AIE) fluorescent mechanism and a specific reaction type. DMF-H2O mixed solvent (Fw 80% V/V) is suitable to disperse AADT for forming 1 × 10−5 mol L−1 solution with an AIE-active fluorescence probe system. Meanwhile, 9-Anthraldehyde also presents good fluorescence at same condition. With the increase of trace Hg (II), the AADT probe shows dual-channel, (turn-off at 429 nm, and turn–on at 511 nm) fluorescence probe character. (R2 > 0.994), which does not interfere each other. The probe demonstrates excellent selectivity, anti-inference properties, and several metal ions and acid ions hardly affect its performance. The LOD of the AADT probe is lower than 2.34 × 10−8 mol L−1, and proper to many common AIE-active probes.

Lubricant additives even performing slightly better in machinery systems would lead in total to the marked reduction of harmful emissions and the significant improvement of fuel economy. Although nanoparticles have demonstrated great potentiality as better lubricant additives, their practical applications have been seriously impeded by their poor colloidal dispersion in base oils. In this work, structurally dynamic gels have been constructed for the first time in base oils by the reversible ring opening reaction of 1,2-dithiolane-containing telechelic polymers. Representative nanoparticles such as MS2 (M = Mo, W), Ag, and Cu can be homogeneously dispersed into the oil gels through strong coordinating interactions with the 1,2-dithiolane groups. Vial inversion experiments displayed that the resulting polymer-inorganic composite gels have long-term colloidal stability at least for one year. As revealed by SRV-IV oscillating reciprocating tribological tests, the coefficient of friction and wear volume of the composite gels drop significantly up to 56% and 99%, respectively. Moreover, the MoS2 based composite gels exhibit a superior load-bearing capacity of > 1000 N. The mechanism behind such excellent lubricating properties is due to the formation of 60–100 nm thick tribofilms containing Fe-oxide compounds and MoS2 nanoparticles on the worn steel surface. This composite-gel concept not only represents a generalized strategy to fully disperse nanoparticles in base oils but also opens a new avenue to developing high-performance lubricant additives for better friction and wear reduction.

Novel imidazole-based ketene dithioacetals show impressive in planta activity against the economically important plant pathogens Alternaria solani, Botryotinia fuckeliana, Erysiphe necator and Zymoseptoria tritici. Especially derivatives of the topical antifungal lanoconazole, which bear an alkynyloxy or a heteroaryl group in the para-position of the phenyl ring, exhibit excellent control of the mentioned phytopathogens. These compounds inhibit 14α -demethylase in the sterol biosynthesis pathway of the fungi. Synthesis routes starting from either benzaldehydes or acetophenones as well as structure-activity relationships are discussed in detail.

A concise total synthesis of tetranorsesquiterpenoids applanatumol Z5 (3), possessing unique 6/5/5 ring system was disclosed with 7-step in 5-pot from commercially available starting materials. The key elements of the synthesis included an unexpected intramolecular dithiolane with alcohol oxidative coupling/deprotection sequence to create the unsaturated lactone as dienophile and a regioselective Diels-Alder reaction to assemble the 6/5/5 tricyclic scaffold including two vicinal quaternary carbon stereocenters. Late stage the diastereo- and regioselective carbonyl reduction led to achieve the total synthesis of (±) applanatumol Z5 (3).

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.

An N3-type, Ru heteroleptic complex, AK1, having one bipyridyl ligand modified with COOH groups for tethering to TiO 2 and a second bipyridyl ligand modified with two lipoic acid units for binding to platinum, was synthesized. The photophysical and spectroelectrochemical properties were studied in solution, on TiO 2 , in a dye-sensitized solar cell and on a Pt wire electrode. The results showed that AK1 can produce a photocurrent on TiO 2 . Furthermore, AK1 binds to Pt via the lipoic acid ligand but not via the carboxylic acid group, and can be electrochemically addressed by the Pt via the lipoic acid linkage.

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.

Herein, we report an enzymatic galactosylation reaction of β-glucopyranosylamide 4 and thioctic acid methyl ester 5 bearing 1,2-dithiolane groups to form a new system of mixed self-assembled monolayers (SAMs) on gold. Characterization of the enzymatic activity was conveniently achieved by mass spectrometry.

Two new complexes [MnIII(HL)2(acac)] and [MnII(HL)2]n have been obtained by reacting manganese(III) acetylacetonate monohydrate or manganese(II) chloride monohydrate with 2-salicylichydrazono-1,3-dithiolane ligand (H2L). Both compounds have been fully characterized by spectroscopic methods and single crystal X-ray diffraction. In the solid state, the molecular packing are described and discussed in term of weak H-bonds and short contacts. The unprecedented bridging coordination mode of this ligand lead to the first 2-salicylichydrazono-1,3-dithiolane-bridged coordination polymer [MnII(HL)2]n. The EPR spectrum of this compound was obtained with g ≈ 2.07, corresponding to a manganese ion (+II) in octahedral high-spin coordination sphere. The MnII complex exhibit paramagnetic behavior corresponding to quasi-isolated metal centers.

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.

A simple route was developed for the synthesis of optically enriched β-amino-α-keto amides. The highly diastereoselective addition of alkyl dithiolanecarboxylates to optically enriched sulfinimines affords the corresponding β-amino-α-keto esters in which the ketone carbonyl group is protected as a dithiolane. Amidation of the ester functionality with a primary amine proceeds readily at room temperature. Treatment with HCl cleaves the N–S bond of the sulfinyl group to provide a free amine functionality, which can then be incorporated into a peptide. Removal of the dithiolane protecting group under oxidative conditions proceeds without epimerization as exemplified by a model dipeptide.

Newly synthesized naphthalene diimide 1 having two dithiolane moieties at its substituted termini bound to double stranded DNA by threading intercalation and the resulting complex was immobilized on the gold surface through a dithiolane-gold linkage as revealed by quartz crystal microbalance (QCM) experiments. DNA with 20-meric double stranded and 24-meric single stranded regions was indirectly immobilized on the gold electrode using this characteristic of 1. Hybridization efficiency was 92%, a value higher than 50% for a thiolated oligonucleotide under identical conditions. When this electrode was subjected to hybridization with a 124-meric target DNA in the presence of ferrocenylnaphthalene diimide (FND) as an electrochemical hybridization indicator, a large current increase was observed deriving from FND bound in the double stranded region newly formed between the probe and target DNA.

Well-defined and homogeneous, contamination-free self-assembled monolayers (SAMs) were fabricated by the chemisorption of lip-NH-p-C{sub 6}H{sub 4}-N {double_bond} N-p-C{sub 6}H{sub 4}-COOH (lip = {alpha}-lipoyl) onto gold. This adsorbate species is composed of a 1,2-dithiolane-based headgroup, an azobenzene-based (and hence photochromic) spacer unit and a carboxylic acid functional group. The SAM constituents are covalently attached to the substrate by the bidentate thiolate anchor groups and exhibit a strongly tilted binding configuration.

Novel 1,2-dithiolane/chroman hybrids bearing heterocyclic rings such as 1,2,4- and 1,3,4-oxadiazole, 1,2,3-triazole and tetrazole were designed and synthesized. The neuroprotective activity of the new analogues was tested against oxidative stress-induced cell death of glutamate-challenged HT22 hippocampal neurons. Our results show that bioisosteric replacement of amide group in 2-position of the chroman moiety, by 1,3,4-oxadiazole did not affect activity. However, analogue 5 bearing the 1,2,4-oxadiazole moiety showed improved neuroprotective activity. The presence of nitrogen heterocycles strongly influences the neuroprotective activity of 5-substituted chroman derivatives, depending on the nature of heterocycle. Replacement of the amide group of the first generation analogues by 1,2,4-oxadiazole or 1,2,3-triazole resulted in significant improvement of the activity against glutamate induced oxidative stress.

A sulfide with a bicyclic squalene hydrocarbon skeleton present in sediments from various depositional settings and of different geological age has been identified by synthesis of a reference compound. In contrast to previous expectations [cf. Schouten, S., Sinninghe Damste, J.S., de Leeuw, J.W., 1995. A novel triterpenoid carbon skeleton in immature sulphur-rich sediments. Geochimica et Cosmochimica Acta 59, 953–958; Gug, S., Schaeffer, P., Adam, P., Klein, S., Motsch, E., Albrecht, P., 2009. Identification of a sulfide derivative with a bicyclic hydrocarbon skeleton related to squalene. Part I: Synthesis of a dithiane triterpenoid. Organic Geochemistry 40, 876–884.], this sulfide bears two “S-spiro type“ thiolane moities, but not the two thiochromane moieties originally envisaged. The synthesis resulted in the formation of a complex isomeric mixture of compounds, all co-eluting in gas chromatography (GC) in the form of one broad peak, as is the case with the geochemical compound. The spiro-type sulfide was formed by intramolecular sulfurization of a polyunsaturated bicyclic squalene derivative of unknown biological origin. The presence of this sulfide in a number of Triassic to Miocene marine sediments from various and contrasting depositional settings (upwelling environments, shallow continental platforms, lagoonal sub-basins, hypersaline environments), all characterized by strongly anoxic conditions, but with or without photic zone anoxia, indicates that the microorganisms biosynthesizing the precursor bicyclic squalene occupy diverse ecological niches.

In this study, a new synthetic route for the total synthesis of (±)-uleine is described. The important step in the synthesis of this alkaloid consists of an intramolecular cyclization of the D ring of the azocino[4,3- b ]indole skeleton. Reduction of ( N -methyl){3-β-ethyl-4-oxo-2,3,4,9-tetrahydrospiro[1 H -carbazole-1,2′(1,3)dithiolane]-2-yl}-2-acetamide with borane yielded the corresponding ( N -methyl){3-β-ethyl-4-hydroxy-2,3,4,9-tetrahydrospiro[1 H -carbazole-1,2′(1,3)dithiolane]-2-yl}-2-acetamide, which underwent acid-catalyzed ring closure to produce azocino[4,3- b ]indole core. Finally, the synthesis of (±)-uleine was completed through several steps from the azocino[4,3- b ]indole core.

The pyruvate dehydrogenase multienzyme assembly (PDH) generates acetyl coenzyme A and reducing equivalents from pyruvate in a multiple-step process that is a nexus of central metabolism. We report crystal structures of the Geobacillus stearothermophilus PDH E1p subunit with ligands that mimic the prereaction complex and the postdecarboxylation product. The structures implicate residues that help to orient substrates, nurture intermediates, and organize surface loops so that they can engage a mobile lipoyl domain that receives the acetyl group and shuttles it to the next active site. The structural and enzymatic data suggest that H128beta performs a dual role: first, as electrostatic catalyst of the reaction of pyruvate with the thiamine cofactor; and second, as a proton donor in the second reaction of acetyl group with the lipoate. We also identify I206alpha as a key residue in mediating the conformation of active-site loops. We propose that a simple conformational flip of the H271alpha side chain assists transfer of the acetyl group from thiamine cofactor to lipoyl domain in synchrony with reduction of the dithiolane ring.

The C-1'-dithiolane Delta(8)-tetrahydrocannabinol (Delta(8)-THC) amphiphilic analogue (-)-2-(6a,7,10,10a-tetrahydro-6,6,9-trimethylhydroxy-6H-dibenzo[b,d]pyranyl)-2-hexyl-1,3-dithiolane (AMG3) is considered as one of the most potent synthetic analgesic cannabinoid (CB) ligands. Its structure is characterized by rigid tricyclic and flexible alkyl chain segments. Its conformational properties have not been fully explored. Structure-activity relationship (SAR) studies on classical CBs showed that the alkyl side chain is the most critical structural part for the receptor activation. However, reported low energy conformers of classical CB analogues vary mainly in the conformation of their alkyl side chain segment. Therefore, comparative molecular dynamics (MD) simulations of low energy conformers of AMG3 were performed in order to investigate its structural and dynamical properties in two different systems. System-I includes ligand and amphoteric solvent DMSO, simulating the biological environment and system-II includes ligand at active site of the homology models of CB1 and CB2 receptors in the solvent. The trajectory analysis results are compared for the systems I and II. In system-I, the dihedral angle defined between aromatic ring and dithiolane ring of AMG3 shows more resistance to be transformed into another torsional angle and the dihedral angle adjacent to dithiolane ring belonging in the alkyl chain has flexibility to adopt gauche+/- and trans dihedral angles. The rest of the dihedral angles within the alkyl chain are all trans. These results point out that wrapped conformations are dynamically less favored in solution than linear conformations. Two possible plane angles defined between the rigid and flexible segments are found to be the most favored and adopting values of approximately 90 degrees and approximately 140 degrees. In system-II, these values are approximately 90 degrees and approximately 120 degrees. Conformers of AMG3 at the CB1 receptor favor to establish a cis conformation defined between aromatic and dithiolane ring and a trans conformation in the CB2 receptor. These different orientations of ligand inside the binding pocket of CB1 and CB2 receptors may explain its different binding affinity in the two receptors. The results of this study can be applied to other synthetic classical CB ligands to produce low energy conformations and can be of general use for the molecules possessing flexible alkyl chain(s). In addition, this study can be useful when restraint of the alkyl chain is sought for optimizing drug design.

Sulfurization of β-dithiolactone (4) gave corresponding 1,2-dithiolane-3-thione (2a) via an ionic intermediate. Oxidation of β-dithiolactone 4 by m-CPBA afforded corresponding S-oxide (11), while dioxide (12) was obtained when 3 equiv of m-CPBA was used. Dithiolane-3-thione 2a reacted with ethylenebis(triphenylphosphine)platinum or tetrakis(triphenylphosphine)palladium to afford the corresponding dithiolato-platinum (20) and dithiolato-palladium (21) complexes in good yields.

A facile and efficient route to functionalized thioamides has been developed by a tandem reaction of 2-acetylmethylene-1,3-dithiolanes via fragmentation of the dithiolane ring upon heating and in the presence of an amine.

Treatment of substituted 1,3-dithiolanes and 1,3-oxathiolanes with methyl diazoacetate in the presence of Rh 2 (OAc) 4 effects ring expansion to the corresponding substituted 1,4-dithiane-2-carboxylates and 1,4-oxathiane-3-carboxylates. The sulfur ylides initially generated in these reactions undergo Stevens rearrangement in competition with both [2,3]-C–C-sigmatropic rearrangement and intramolecular fragmentation. In the case of 2-styryl-substituted 1,3-oxathiolane and 1,3-dithiolane, ring expansion on one-, three- and four-carbons subsequently takes place.

The new Mn ( HL ) 2 L 2 ′ complexes with 2-salicyloylhydrazono-1,3-dithiolane ligand (H2L) have been obtained with good yields (≈85%) by reacting manganese (II) acetate tetrahydrate or manganese (II) acetylacetonate with 2-salicyloylhydrazono-1,3-dithiolane ligand in DMF, THF or Py (L′). These compounds have been fully characterized by spectroscopic methods and single crystal X-ray diffraction. In the solid state, supramolecular networks are described and discussed in terms of weak H-bonds and short contacts. The new monomeric complexes will be considered as candidates to obtain polynuclear complexes.

Copper(II) tetrafluoroborate hydrate is a new and extremely efficient catalyst for 1,3-dithiolane/dithiane formation from aromatic, heteroaromatic and aliphatic aldehydes and cyclic saturated ketones in 1–5 min under solvent-free conditions at room temperature. The reaction is compatible with other functionalities such as ether, ester, hydroxyl, halide, nitro and cyano groups and exhibits excellent chemoselectivity. α,β-Unsaturated aldehydes/ketones lead to selective formation of 1,3-dithiolanes instead of Michael addition products. For substrates bearing an aldehyde and a ketone carbonyl group, chemoselective dithiolane formation takes place with the aldehyde.

Carbonyl compounds have been successfully converted into their corresponding dithioacetals, dithiolanes and dithianes derivatives in excellent yields with thiol (ethanethiol and thiophenol), 1,2-ethanedithiol and 1,3-propanedithiol using a catalytic amount of iodine supported on natural phosphate. In addition, by employing this catalyst, high chemoselective thioacetalization of carbonyl compounds have been achieved.

Ion pair amphiphiles (IPA) composed of one proton-deionizable single or double alkyl chain ammonium surfactant and one anionic carboxylate surfactant with polymerizable dithiolane ring are prepared to develop polymerized microcapsules that can recognize pH change and transform itself under basic condition, thus releasing encapsulated materials at the desired point. Combination of pH-sensitivity and polymeric solid structure, if fully developed, endows the IPA vesicle with smart function that is highly valuable in drug delivery application. Reasons for such high pH-sensitive vesicle transformation are sought from combined physical properties such as turbidity, zeta potential, surface tension, and release rate of marker through the vesicle membrane.

New dithiane or dithiolane derivatives of gossypol and gossypolone were synthesized with dithiolethane or dithiolpropane in the presence of BF(3)/Et(2)O. These thioderivatives exhibited low toxicity on KB cells (human epidermoid carcinoma cells of the mouth). They react easily with electrophiles in aprotic solvents to regenerate gossypolone or to form dehydrogossypoldithianes and dehydrogossypoldithiolanes, which display higher toxicity on KB cells. In addition, the low toxicity of gossypol thioderivatives was reversed by nitric oxide donors in physiological media. These experiments suggest that gossypol and gossypolone dithianes and dithiolanes can be used as prodrugs that target tumor cells surrounded by high concentrations of nitric oxide.

Molecules containing a dithiolane moiety are widely investigated due to their antioxidant properties. The archetypal representative of this class of compounds is lipoic acid and indeed the lipoic acid–dihydrolipoic acid couple is part of the antioxidant defence system of the cell. In the course of a program aiming to find improved antioxidants effective in vivo, we designed, synthesised and pharmacologically investigated new lipoic acid analogs. The salient feature of these structures is the connection, via a thioamide or a thiocarbamate, of a 1,2-dithiolane moiety bearing a carbon chain and a N -alkyl-substituted morpholine ring. It was expected that the antioxidant and chelating properties of these functional groups combined with the basicity of the morpholine ring will impact on the antioxidant as well as on the partition and solubility characteristics of the compounds. Indeed in vitro and in vivo pharmacological investigation showed that these new molecules and especially those containing a thiocarbamate linker possess superior antioxidant properties compared with α-lipoic acid and to the amide or carbamate linker analogs. In particular, some of these compounds efficiently cross the blood brain barrier (BBB) thus providing efficient protection from lethality in a situation of induced oxidative stress. Moreover the absence of the 1,2-dithiolane moiety does not completely abolish antioxidant effects thus demonstrating that these compounds are distinct new chemical entities and not merely lipoic acid prodrugs. The chemical and pharmacological features of these new antioxidants are presented and discussed in the following paper.

2-(4-Methylpyridinium)-5-(4-pyridinium)-1,3-dithiolane-2,4-dicarboxylic acid dithiocyanate monohydrate (2) was obtained by a spontaneous double electrophilic addition reaction between two molecules of 3-(4-pyridine)-2-mercaptopropenoic acid (1), and characterized by spectroscopic methods. The structure of 2, isolated as crystals, was determined by X-ray diffraction method: monoclinic, P21/c, a=8.5174(7) A , b=7.4996(5) A , c=34.014(3) A , β=93.303(7)°, V=2169.1(3) A 3 , Z=4. In the lattice of 2 the stability is mainly due to intra and intermolecular stack formation between the aromatic ring system of pyridine and the carboxylic groups.

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.

A versatile preparation of an enantiopure aldehyde useful for the asymmetric total synthesis of filipin III was developed using a chiral oxazaborolidinone-promoted asymmetric aldol reaction with a dithiolane silyl nucleophile. The sign and magnitude of the specific rotation of the aldehyde, (4 R ,5 R )-2,2-dimethyl-5-formyl-4-pentyl-1,3-dioxane, were reconfirmed.

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.

In the presence of electron donors, ethyl phenylglyoxylate generally forms adducts as the result of cross-coupling between the radical pai after a proton transfer. Quenching rate constants of triplet methyl phenylglyoxylate by hydrogen and electron donors were measured. Electron donors quench the excited state more than three orders of magnitude more rapidly than hydrogen donors. Quantum yields of the starting material's disappearance were shown to be very different in the reaction with a hydrogen donor to that with an electron donor. Photoreduction by dithiane (dithiolane) situated intramolecularly was also studied. © 1998 Elsevier Science S.A. All rights reserved

A mild, efficient and solvent-free protocol for conversion of aldehydes and ketones into their corresponding 1,3-dithiolanes using 1,2-ethanedithiol in the presence of a catalytic amount of SnCl 2 ·2H 2 O is reported.

A pharmacophore derived from the structure of the dithiolane derivative of haloperidol bound in the active site of the HIV-1 protease (HIV-1 PR) has been used to search a three-dimensional database for new inhibitory frameworks. This search identified an FMOC-protected N-tosyl arginine as a lead candidate. A derivative in which the arginine carboxyl has been converted to an amide has been crystallized with HIV-1 PR and the structure has been determined to a resolution of 2.5 A with a final R-factor of 18.5%. The inhibitor binds in an extended conformation that results in occupancy of the S2, S1', and S3' subsites of the active site. Initial structure-activity studies indicate that: (1) the FMOC fluorenyl moiety interacts closely with active site residues and is important for binding; (2) the N(G)-tosyl group is necessary to suppress protonation of the arginine guanidinyl terminus; and (3) the arginine carboxamide function is involved in interactions with the water coordinated to the catalytic aspartyl groups. FMOC-protected arginine derivatives, which appear to be relatively specific and nontoxic, offer promise for the development of useful HIV-1 protease inhibitors.

The chiral oxazaborolidinone-catalysed aldol reaction of a silyl ketene acetal involving a dithiolane moiety with β-silyloxy aldehyde resulted in the production of syn - and anti -1,3-diols with complete stereoselection by the choice of the stereochemistry of the catalyst. This reaction is an elegant example of enantioselective acyclic stereoselection under catalyst control.

Electrooxidation of thioacetals such as dibenzyl S,S-acetal and dithiolane in aqueous acetonitrile effected selective deprotections to carbonyl compounds; it is possible to deprotect a ketone thioacetal in preference to an aldehyde thioacetal.

Asymmetric synthesis of dithiolane aldols 3 was achieved in good yields by using silyl ketene acetal 1 , derived from ethyl 1,3-dithiolane-2-carboxylate, in the chiral oxazaborolidinone ( L-1 and D-2 )-promoted aldol reaction and desulfurization of 3 resulted in production of acetate aldols 4 in high enantiomerc purity.

Nitrosonium tetrafluoroborate in conjunction with pyridinium poly(hydrogen fluoride) has been found to be excellent desulfurative fluorination reagent. In NO+BF4−/PPHF system, mono-fluorides and gem-difluordes have been obtained in high yields from the corresponding phenylsulfides and dithiolane derivatives, respectively.

Summary Ten semicarbazone and nine thiosemicarbazone 1,3-dithiolanes (α, β and γ) were prepared and tested as radioprotector agents. Dithiolane is well known for its radioprotective properties; this compound protects 78% of mice if 500 mg/kg is administered 15 min before a 850 cGy irradiation dose [1]. For the first time, the combination of a semicarbazone or thiosemicarbazone group with a dithiolane moiety has been achieved within a single molecule. We also studied the potential anticonvulsant activities of these compounds, since benzodiazepines have been observed to greatly decrease radioinduced convulsions. Among the tested compounds, the correlation between the anticonvulsant activity and the radioprotective effect was not systematic.

Dithiolane-isocyanate imminium methylides which are a new type of azomethine methylide-derived 1,3-dipole undergo efficient and regioselective cycloaddition to conjugated carbonyls and thiocarbonyls to yield predominantly 1,3-oxazolidine- and thiazolidine-2-thiones formed from the initial cycloadducts via loss of thiirane.

The effect of the addition of water on the asymmetric oxidation of an acyl dithiane and an acyl dithiolane has been studied. The use of enantiomerically pure dithiolane sulphoxides is demonstrated in a highly selective synthesis of (R)-3-benzoyloxy-2-butanone which depends upon a diastereoselective ketone reduction.

Kottamide E, a novel alkaloid containing dibrominated indole enamide, oxalic acid diamide and 4-amino-1,2-dithiolane-4-carboxamide moieties, has been isolated from the New Zealand ascidian Pycnoclavella kottae. Characterisation was achieved by interpretation of spectroscopic data.

We outline a modular building block strategy for the covalent assembly of porphyrin-containing model systems. Molecular design issues for the synthesis of porphyrin dimers, dye-porphyrin dyads, and multi-porphyrin arrays have been used to guide the development of this approach. The major design constraints are to achieve directed coupling of free base and/or metalloporphyrin building blocks in dilute solution under non-acidic non-metalating conditions. A set of 24 porphyrin building blocks has been synthesized. The porphyrins are prepared by reaction of substituted benzaldehydes with pyrrole using the two-step one-flask room temperature porphyrin synthesis. Routes to 7 substituted aldehydes are described. Each porphyrin bears one or four functional groups, and many also are facially-encumbered in order to achieve increased solubility. 12 functional groups that meet the design criteria include those that can be reacted directly in coupling reactions such as active esters, α-chloroacetamido, benzoyl, and iodo groups, and others that require deprotection prior to coupling, such as phthalimidomethyl, FMOC-prolyl, trimethylsilylethynyl, dithiolane, methoxycarbonyl, and trimethylsilylethoxycarbonyl groups. The synthesis of 13 porphyrin dimers and dye-porphyrin dyads has been explored as a testbed for refining strategies for the synthesis of molecular devices containing multiple porphyrins and other components. The coupling strategies investigated have yielded dimers or dyads with subunits linked by amide, butadiyne, ethyne, or thiourea groups. This building block approach should enable rapid assembly of architecturally-defined porphyrin-based model systems.

Seventeen β- or γ-oximinoether-1,3-dithiolanes were prepared and tested as radioprotector agents. Dithiolanes are well known for their radioprotective properties, and, for the first time, the combination of an oximinoether group and dithiolane moiety has been achieved within a single molecule. Five molecules 2a, 2d, 3a, 3b and 3j have immediate and sustained radioprotective activity.

Fourteen γ-thiazolidine-1,3-dithiolanes were prepared and tested as radioprotective agents. The combination within a single molecule of thiazolidine and dithiolane moieties, both of which are known for their radioprotective properties, was achieved for the first time. Several molecules show significant radioprotective activity: immediate 4I ; delayed 4b, 4f, 4h ; or immediate and prolonged 4a .

The preparation of the following compounds is reported: Cu2(dtt)Cl2, Cu(dtt)X (XCl, Br, I; dtt= 1,3-dithiolane-2-thione). The compounds are diamagnetic and stable to aerial oxidation at room temperature. IR spectroscopic results suggest that the thione-sulfur is involved in the coordination, and that a higher donation of this atom occur in Cu2(dtt)Cl2. Crystals of [Cu2(dtt)Cl2]n are monoclinic, space group P21/c with a=10.970(6), b=13.274(6), c=5.952(5) A, β=92.71(2)°, Z=4. The structure consists of two distinct polymeric chains ···CuClCuCl··· held together by bridging thionic sulfur atoms of the ligand. The Cu atoms in the two chains are different, having a distorted tetrahedral and trigonal coordination, respectively.

2-Trimethylsilyl-1,3-dithiolane, easily obtainable through transthioacetalization of corresponding silylated acetals, can be efficiently reacted, under fluoride-ion catalysis, with different organic electrophiles, leading to a general and mild functionalization protocol. This reactivity discloses the ability of compound 3 to act as a masked dithiolane anion.