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A series of carba- or oxa[5]-, [6]-, [7]-, and -[19]helicene (di)thiols was prepared. The Miyazaki-Newman-Kwart rearrangement of (dimethylcarbamothioyl)oxy (oxa)helicenes in a flow reactor or nucleophilic substitution of dichloro (oxa)helicenes with alkanethiolates were used in the sulfanylation step. Despite the high temperatures employed in this key step, no conformational scrambling was observed during the asymmetric synthesis of the diastereo- and enantiopure oxahelicenes. Single-molecule conductivity of the longest oxa[19]helicene dithiol derivative was studied by the scanning tunneling microscopy break-junction method.

Aerobic oxidation reaction of [70]fullerene with aliphatic primary thiols in the presence of n-butylamine was studied. The reaction afforded both the fullerene dithiol (2) and dithiol epoxide (3) compounds, which were characterized by

An efficient method for the synthesis of symmetrical and unsymmetrical substituted thiourea derivatives by means of simple condensation between available building blocks such as amines and carbon disulfide in aqueous medium is presented. This protocol works smoothly with aliphatic primary amines to afford various di- and trisubstituted thiourea derivatives. The present method is also useful in synthesizing various substituted 2-mercapto imidazole heterocycles. This method proceeds through a xanthate (amino dithiol deivative) intermediate, unlike isothiocyanate as in an earlier known method.

Base-mediated double conjugate addition of 1,3-propane dithiol to various silylated propargylic aldehydes and ketones allows for an efficient and scalable synthesis of beta-carbonyl silyl-1,3-dithianes.

The solution phase self-assembly of boronate esters, diazaboroles, oxathiaboroles, and dithiaboroles from the condensation of arylboronic acids with aromatic diol, diamine, hydroxythiol, and dithiol compounds in chloroform has been investigated by (1)H NMR spectroscopy and computational methods. Six arylboronic acids were included in the investigations with each boronic acid varying in the substituent at its 4-position. Both computational and experimental results show that the para-substituent of the arylboronic acid does not significantly influence the favorability of forming a condensation product with a given organic donor. The type of donor, however, greatly influences the favorability of self-assembly. (1)H NMR spectroscopy indicates that condensation reactions between arylboronic acids and catechol to give boronate esters are the most favored thermodynamically, followed by diazaborole formation. Computational investigations support this conclusion. Neither oxathiaboroles nor dithiaboroles form spontaneously at equilibrium in chloroform at room temperature. Computational results suggest that the effect of borylation on the frontier orbitals of each donor helps to explain differences in the favorability of their condensation reactions with arylboronic acids. The results can inform the use of boronic acids as they are increasingly utilized in the dynamic self-assembly of organic materials and as components in dynamic combinatorial libraries.

Crossover Linstead macrocyclization of a doubly norbornenyl-functionalized dimercaptomaleonitrile with dipropylmaleonitrile gave a crude mixture of porphyrazines containing the hexapropylporphyrazinedithiol magnesium complex. The mixture was subjected to ring-opening metathesis polymerization to yield the insoluble porphyrazinedithiol-functionalized polymers. Cleavage from the polymer backbone using mercury(II) acetate followed by reaction with electrophiles gave access to a range of thioporphyrazinedithiol derivatives including solitaire porphyrazines. Studies into the possible uses of hexapropyl-2,3-di-(carboxymethylthio)porphyrazine in sensing metal cations in solution are described.

We report the synthesis of a new series of cyclophanes 11a−d by ester-forming macrocyclization reactions of diol 9 with the dicarbonyl chloride derivatives of benzene, thiophene, ferrocene, and dip...

Reliable completely odorless syntheses of soluble copolymeric reagents of styrene type containing propane-1,3-dithiol functions able to convert carbonyl compounds into 1,3-dithiane derivatives and to support other useful transformations are reported together with their progenitor copolymers containing benzenesulfonate or thioacetate groups perfectly stable in open air and suitable for unlimited storage. The effectiveness of the prepared reagents as tools for polymer-supported syntheses to produce ketones by aldehyde umpolung and alkylation is tested in the conversion of benzaldehyde to phenyl n-hexyl ketone starting from copolymers with different contents of active units and molecular weights. To facilitate the adaptation of the prepared soluble copolymeric reagents to other possible applications, a table of solvents and nonsolvents is presented.

The synthesis and physical properties of four series of novel fluorene push−pull compounds (4−7) of the D−π−A type with intramolecular charge transfer (from 1,3- and 1,2-dithiole and 1,3-selenathiole donor (D) moieties) are described. The nature of the heteroatom (S or Se) in the donor fragment has no effect on the maxima of intramolecular absorption bands (λICT), whereas a change of position of the heteroatoms in the dithiole moiety from 1,3 to 1,2 leads to a substantial bathochromic shift in λICT. Solvatochromism, thermochromism, and negative halochromism in these compounds are demonstrated. Cyclic voltammograms of 4−7 exhibit two, separate, single-electron reversible redox waves, the potentials of which (as well as the ICT energies in the molecules) are quantitatively described by σp- constants of the substituents in the fluorene ring. Compounds 4−7 exhibit reversible salt formation in sulfuric acid, and for compound 5g in diluted sulfuric acid an additional absorption in the near-IR region has been ob...

Cyclophanes of the type 1 and 2, with large cavity sizes, have been synthesized from the corresponding dichloride 8 or 8a and o-xylene-�,�?-dithiol (9), p-xylene-�,�?-dithiol (10), or m-terphenyldithiol (11). Similarly, cyclophanes of the type 3 with intra-annular functionality have been obtained by the coupling of the corresponding dithiol 15 or 19 and m-terphenyl dibromide 5, 5a, 5b, or 5c. With the aim of introducing multifunctionality, cyclophanes of the type 21 and 23 were prepared from 3,5-bis(mercaptomethyl)anisole or 3,5-bis(mercaptomethyl)phenol and the corresponding substituted m-terphenyl dibromide 5b or 5c. Cyclophanes 24, 24a, 24b, and 32, with a new type of cage structure, have been obtained by the coupling of the corresponding tetrathiol 29 with 2 equiv of the dibromides 5c, 5a, and 5b or 1 equiv of the tetrabromide 31, respectively. Further, the sodium salts of the cyclophanes 3c, 21, and 24b were completely characterized by 1H NMR spectroscopy. XRD analysis of the cyclophane 21 revealed the presence of an ethanol molecule inside the cavity, indicating the facile formation of a host-guest complex.

Rate and equilibrium constants are reported for the thiol/disulfide exchange reactions of the peptide hormone somatostatin with glutathione (GSH). GSH reacts with the disulfide bond of somatostatin to form somatostatin-glutathione mixed disulfides (Cys3-SH, Cys14-SSG and Cys3-SSG, Cys14-SH), each of which can react with another molecule of GSH to give the reduced dithiol form of somatostatin and GSSG. The mixed disulfides also can undergo intramolecular thiol/disulfide exchange reactions to re-form the disulfide bond of somatostatin or to interconvert to the other mixed disulfide. Analysis of the forward and reverse rate constants indicates that, at physiological concentrations of GSH, the intramolecular thiol/disulfide exchange reactions that re-form the disulfide bond of somatostatin are much faster than reaction of the mixed disulfides with another molecule of GSH, even though the intramolecular reaction involves closure of a 38-membered ring. Thus, even though the disulfide bond of somatostatin is rea...

Bis-fused pi-electron donors composed of tetrathiafulvalene (TTF) and 2-(thiopyran-4-ylidene)-1,3-dithiole (TPDT), 2-(1,3-dithiol-2-ylidene)-5-(thiopyran-4-ylidene)-1,3,4,6-tetrathiapentalene (1a, TPDT-TTP), and its derivatives (1b-d, 2a-d) have been synthesized as donor components for organic conductors. An X-ray structure analysis of bis(methylthio)-1 (1c) revealed that the TPDT-TTP skeleton is almost planar except for the outer 1,3-dithiole ring, and that the crystal has a two-dimensional "theta-type" arrangement of molecules. The cyclic voltammograms of TPDT-TTPs exhibit four pairs of single-electron redox waves. The first oxidation potential (E(1)) of 1a (+0.37 V vs SCE, in PhCN) is comparable to that of TTF (+0.35 V) and is higher by 0.1 V than that of TPDT (+0.27 V). The observed substituent effect on E(1) values suggests that the first one-electron oxidation mainly occurs in the 2-(thiopyran-4-ylidene)-1,3-dithiole (TPDT) moiety. On the other hand, on-site coulombic repulsion estimated from the E(2) - E(1) value is lower than in TTF and TPDT. MNDO MO calculations reveal that all the sulfur atoms in the 1,3-dithiole rings have the same phase in the HOMO, a condition necessary for realization of effective transverse intermolecular interaction. The present donors have produced many charge-transfer complexes and cation radical salts showing relatively high conductivity (sigma(rt) = 10(-)(1)-10(1) S cm(-)(1)), several of which display metallic temperature dependence.

The title Wittig reagent (5) has been prepared in three steps (84% overall yield) from 4,5-bis-(benzoylthio)-1,3-dithiole-2-thione. Reac- tions of ylide (7), generated by treatment of (5) with diisopropyle- thylamine at room temperature, have been exploited in the synthesis of new unsymmetrical tetrathiafulvalenes and 1,3-dithiol-2-ylidene deriva- tives. Subsequent removal of the benzoyl protecting group with sodium ethoxide liberates the transient TTF-dithiolate or 1,3-dithiole-dithi- olate anions which can be alkylated in situ. The X-ray crystal structu- res of compounds (17) and (18) are reported: close nonbonded S-O intra- molecular interactions are observed in both structures

Rate and equilibrium constants are reported for reduction of the disulfide bonds in the neurohypophyseal peptide hormones oxytocin (OT) and arginine-vasopressin (AVP) by thiol/disulfide interchange with glutathione (GSH) and cysteine (CySH) and for formation of the disulfide bonds by thiol/disulfide interchange with oxidized glutathione (GSSG) and cystine (CySSCy). The reactions take place in two steps. In the first step of the reduction reactions, AVP and OT react with GSH and CySH to form peptide-GSH and peptide-CySH mixed disulfides, which in turn react with another molecule of GSH or CySH to give the reduced dithiol form of the peptide and GSSG or CySSCy. Analysis of the forward and reverse rate constants indicates that which step is rate determining depends on the concentration of GSH or CySH. At physiological concentrations of GSH and CySH, intramolecular thiol/disulfide interchange in the mixed disulfides to reform the native disulfide bonds is faster than reaction with another molecule of GSH or CySH, even though intramolecular thiol/disulfide interchange involves closure of 20-membered rings. Rate constants for reaction of GSH and CySH with the disulfide bonds of AVP and OT are 1-2 orders of magnitude larger than for reaction with disulfide bonds formed by two cysteine-containing peptides, which suggests that the disulfide bonds in the neurohypophyseal peptide hormones are strained. Equilibrium constants are also reported for reaction of GSH with the hexapeptide analogs of AVP and OT, pressinoic acid (PA), and tocinoic acid (TA). A reduction potential of -0.216 V was calculated for the disulfide bonds of OT and TA from the thiol/disulfide interchange equilibrium constants. Reduction potentials of -0.229 V and -0.227 V were calculated for the disulfide bonds in AVP and PA, respectively. The similarity of the reduction potentials for OT and TA and for AVP and PA indicates that the acylcic tripeptide tails of OT and AVP have little affect on the redox properties of their disulfides bonds

4-(1,3-Dithiol-2-ylidene)-4H-cyclopenta[2,1-b;3,4-b']dithiophenes 1 and 7-(1,3-dithiol-2-ylidene)-7H-cyclopenta[1,2-b;4,3-b']]dithiophenes 2 were prepared by Wittig-Horner or Wittig reactions. The X-ray structural analyses of the parent compounds 1a and 2a reveal that both molecules have planar structures with short intermolecular S...S contacts, and 2a additionally has short intramolecular S...S contacts. They have low oxidation potentials and absorptions in a long wavelength region due to the 1,3-dithiole skeleton. Electrochemical oxidation of 1 and 2 afforded the corresponding polymers 3 and 4, which have low oxidation potentials. Electrochemically dedoped films of 3 and 4 have interband absorptions at 610-690 nm and 420-590 nm, respectively, in their electronic spectra

The reaction of dithiols with 1,3-dichloroacetone under high dilution and catalyzed by cesium carbonate in DMF affords macrocyclic ketones in good yield. Examples of functionalized cyclophanes prepared in this way include 10, 15, 16, 10, 21, and 24. With NaOMe/MeOH as the base, dithiol 14 gave ring-contracted ketone 17 in low yield, in addition to the expected 15 and 16. Ketone 17 was the sole product, in good yield, from 17 and 1,1-dichloroacetone. NaOMe/MeOH also brought about the novel ring contraction of 10 to 11 and 11 to 12. X-ray structures of 10, 12, 16, 19, and 21 are briefly described. Possible mechanisms for the formation of 17 from 14 and for the rearrangement of 10 → 11 → 12 are discussed

Acid-base properties of the native, disulfide and reduced dithiol forms of oxycotin, arginine-vasopressin, tocinoic acid, pressinoic acid, and tocimanide were studied by 500-MHz 1 H NMR-PH titrations. Cysteine methyl ester and cysteinylglycine served as model compounds for the N-terminal cysteine-1 residue of the reduced oligopeptides and were studied by Uv, 1 H NMR, and pHmetry

Glycals derived from hexopyranoses permit the incorporation of iodine at C-2 as well as elaboration of an olefinic residue via the C-5-hydroxymethyl group. Radical cyclization of these functionalities leads to bicyclic systems whose bridge sizes depend on the lengths of the olefinic appendages. Hydrolysis of the anomeric centers of the [2.2.1] structures leads spontaneously to cyclopentane derivatives. However, with [2.2.2] structures, the hemiacetal intermediates are stable in bicyclic forms but are opened readily upon mcerpatolysis with propane dithiol to give cyclohexane derivatives. © 1992, American Chemical Society. All rights reserved.

Introduction of a disulfide unit into the linker of a hemicarcerand creates a new way to control the entry and exit of guests. When the disulfide bond is reduced to two thiols, the "gate" opens, and guests can freely enter the hydrophobic core of the hemicarcerand. However, when the gate is closed, the host must be heated in the presense of excess guest in order for complexation to result. Several novel hemicarceplexes of this type have been synthesized. Molecular mechanics calculations are employed to explore the differing stabilities and ease of complexation of these host-guest complexes.

The synthesis of several synthetically useful 2,6-disubstituted benzobisthiazoles is described. The method is based on the Lewis acid-catalyzed ring-closing reaction between substituted orthoesters and diamino benzene dithiol. The resulting benzobisthiazoles are obtained cleanly and in good yields. These materials are of interest for the development of new organic semiconductors.

We report the synthesis by Suzuki cross-coupling methodology of oligo(arylene) molecular wires with protected thiolates at both termini and a central electron-acceptor unit (3,5-dinitrofluorenone, compounds 10-12) or an electron-donor unit [9-(1,3-dithiol-2-ylidene)fluorene, compounds 14-17] in the backbone. Core reagents are 2,7-dibromo-3,5-dinitrofluorenone 7 (obtained by nitration of 2,7-dibromofluorenone) and 2,7-dibromo-9-(4,5-dimethyl-1,3-dithiol-2-ylidene)fluorene 13. The solution electrochemical redox properties of these oligo(arylene) derivatives have been studied. The reduction CVs of the dinitrofluorenone-containing molecules display three reversible/quasireversible couples yielding, sequentially, radical anion, dianion, and radical trianion species, e.g., for 11 E(1red) -1.02 V (vs. Ag/Ag(+) in THF). The 1,3-dithiol-2-ylidene unit imparts good electron donor properties to molecules 14, 15, and 16 with radical cation formation observed at E(ox) ca. 0.65 V (vs. Ag/Ag(+) in DCM). We also report studies on the assembly of 11 and 15 on gold substrates. Current-voltage (I-V) characteristics and X-ray photoelectron spectra of the monolayers reveal that 11 assembles via competing S-Au and NO(2)-Au interactions. This unusual phenomenon is ascribed to the very electron deficient dinitrofluorenone core of 11 weakening the S-Au interaction. An important conclusion is that thiolated molecules which possess strongly electron-withdrawing core units, especially those containing nitro groups, may not be suitable for controlled assembly in junctions. In contrast, 15 assembles via conventional S-Au interactions.

The chiral dithiepine 3 was selectively oxidized to all possible oxides: the sulfoxide 9, the sulfone 16, the sulfone-sulfoxide 20, the disulfoxide 21, and the disulfone 22. The sulfinyl oxygens of 9, 14, 20, and 21 are always in the pseudoaxial configuration, as shown by the X-ray structure determination of 11a. Reaction of the anions of 3, 9, and 16 with methyl iodide, benzaldehyde, or acetophenone occurs efficiently. The stereoselectivity of the processes is high and maximized in sulfoxide 9, where the contributions of the chiral binaphthyl residue and the sulfoxide appear to occur synergistically. The alcohols derived from reaction of the anions of 3, 9, and 16 with benzaldehyde and acetophenone were also prepared in high yield and stereoselectivity via reduction or methylation of the phenyl ketone 8 and of its oxidized homologues 14 and 19. Alcohol 6a, prepared in 8.2 ratio in the reaction of 3 with benzaldehyde, was obtained as a single diastereoisomer in the reduction of 8 with lithium aluminum hydride

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

Derivatives of 9,10-bis(1,3-dithiol-2-ylidene)-9,10-dihydroanthracene (ex-TTF) have been synthesized by a new synthetic methodology, viz., direct phosphite-mediated cross-couplings of anthraquinone with 1,3-dithiole-2-thione derivatives. These ex-TTFs bear one, two, or four cyanoethyl-protected thiol groups on the dithiole rings. Deprotection (NaOMe, MeOH, DMF, 20 degrees C) and trapping of the transient thiolates with electrophiles have afforded the new ex-TTF trimer 19, dimeric cyclophanes 22 and 25, the tetrakis(hydroxyethylthio) derivative 23, and the strained cyclophane 24. Solution redox properties have been studied by cyclic voltammetry. For compounds 19, 22, and 25 each ex-TTF unit behaves as an independent 2-electron redox system giving rise to a single, quasi-reversible 6-, 4-, and 4-electron wave, respectively. The Eox value for 24 (0 --2+ wave) is positively shifted by 290 mV compared to that of its precursor 15 due to the short bridge in 24 obstructing the conformational change which accompanies oxidation. X-ray crystal structures of 23.2.5MeOH, 23.1.5MeCN, 24.CH2Cl2, and 24.1.5CH2Cl2 show the saddle-shape folding (typical of ex-TTF derivatives), which in 24 is enhanced by the pentamethylene chain bridging the dithiole units. Both solvates of 23 show an unprecedented crystal packing motif due to hydrogen bonding.

Whereas irradiation of 4,5-dithiophen-2-yl[1,3]dithiol-2-one leads to the expected 2,3,5,6-tetrathiophen-2-yl-1,4-dithiine product, similar reaction of thiophen-3-yl-substituted [1,3]dithiol-2-ones leads to thieno[3,4-c]dithiines via a unique ring cleavage reaction.

A new class of dithiostannanes and dithiogermanes have been prepared from 1,1'-binaphthyl-2,2'-dithiol and 3,3'-bis(trimethylsilyl)-1,1'-binaphtho-2,2'-dithiol. While reduction of 4-butyl-4-chloro-3,5-dithia-4-stanna-cyclohepta[2,1-a;3,4-a']dinaphthalene to the corresponding tin hydride was unsuccessful, 4-tert-butyl-3,5-dithia-4-germa-cyclohepta[2,1-a;3,4-a']dinaphthalene and 4-tert-butyl-2,6-bis(trimethylsilyl)-3,5-dithia-4-germa-cyclohepta[2,1-a;3,4-a']dinaphthalene were obtained by reduction of the parent germanium chlorides with NaBH(4) and LiBH(4), respectively. Kinetic constants for hydrogen transfer to a primary alkyl radical were measured for both germanium hydrides. Reduction of alpha-halo carbonyl compounds by these germanium hydrides occurs with moderate ee values (up to 42%), while hydrogermylation of methyl methacrylate occurs with low selectivity (3/1) for the former hydride but high selectivity (10/1) for the latter.

An improved and efficient synthetic route to four functionalized bis(ethylenedithio)-tetrathiafulvalene (BEDT-TTF) derivatives 2-5 is reported. Tetrathiolate 1 was readily prepared from 2,2'-bis(1,3,4,6-tetrathiapentalen-5-one) under carefully controlled conditions. Subsequent reaction of 1 with selected primary alkyl halides affords new functionalized BEDT-TTF derivatives in good yields.

Both cis- and trans-fused 4a,5,6,7,8,8a-hexahydro-2H,4H-1,3-benzodithiine together with their 2-methyl and 2,2-dimethyl derivatives were prepared as racemates from the appropriate dithiols obtained via multistep syntheses. The products were characterized by 1 H and 13 C NMR, mass spectrometry, and for two of the cis-fused compounds by X-ray diffraction. 1 H, 1 H vicinal coupling constants indicated that all compounds attain chair-chair conformations as their predominant conformations. All three trans-fused isomers exist in totally biased chair-chair conformations and are essentially conformationally locked, whereas the cis-fused compounds are conformationally mobile and can potentially attain either the S-in or the S-out conformation. The interconversion of the conformers is fast on the NMR time-scale at ambient temperatures, but at 213 K 4ar,5,6,7,8,-8ac-hexahydro-1,3-benzodithiine freezes out into a 83:17 mixture of the S-in and S-out forms, respectively. Both 2c-methyl-4ar,5,6,7,8,8ac-hexahydro-1,3-dithiine and the dimethyl derivative adopt almost exclusively the S-in conformer at ambient temperature whereas 2t-methyl-4ar,5,6,7,8,-8ac-hexahydro-1,3-dithiine is a 5:1 mixture of the S-out and S-in conformers.

Aus den Dihalogen- oder Disulfonyloxy-Derivaten (I) entstehen mit Natriumsulfid cyclische und oligomere Disulfide (II) bzw. (III), die mit Lithiumalanat zu den Dimercaptanen (IV) reduziert werden.

Etude de l'interconversion benzo-dithia-22-crown-7/bis-[mercapto-8 dioxa-3,6octyloxy]-1,2 benzene, de l'extraction de metaux alcalins par ces composes et de leurs proprietes redox

Alkyl-substituted polyether diols (or polythioether diols), which are potential precursors to substituted crown ethers, are produced in high yield by the selective reductive cleavage of C−O bonds in bis(cyclic acetals) [or bis(cyclic hemithioacetals)] by borane or monochloroborane