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[Figure not available: see fulltext.] Dihetaryl thioketones possessing thiophen-2-yl and selenophen-2-yl rings react as “superdienophilic” reagents with nonactivated 1,3-dienes such as 2,3-dimethylbuta-1,3-diene, cyclopentadiene, and mixtures of isomeric

Structural, kinetic, and spectroscopic studies show that the mechanism for the thiation of organic carbonyls by Lawesson's reagent involves monomeric RPS2 intermediates.

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The goal of the present study was elaboration of an efficient and simple protocol for the preparation of hetaryl and ferrocenyl functionalized thioketones via treatment of the corresponding ketones with Lawesson's reagent (L.R.) under microwave irradiatio

Reaction of benzilmonohydrazone (1) with S4N4 gives the azine (6) and not the 2-H-imidazole (2); this invalidates the claim that (2) is not the intermediate in the formation of N-benzoyltriphenylimidazole from benzil and ammonia.S4N4 converts diphenylketene into thiobenzophenone.

Trimethylsilyldiazomethane (TMS-CHN2) reacts readily with hetaryl thioketones to give sterically crowded 2-trimethylsilyl- 4,4,5,5-tetrahetaryl-1,3-dithiolanes with complete regioselectivity at -75 °C as well as at rt. Thiofluorenone, a relatively stable and highly reactive aryl thioketone, yields upon treatment with TMS-CHN2at -60 °C the corresponding 1,3,4-thiadiazoline. This unstable cycloadduct undergoes decomposition at ca. -45 °C and the silylated thiocarbonyl S-methanide generated thereby is trapped with complete regioselectivity by aryl or hetaryl thioketones forming also sterically crowded 2-trimethylsilyl-1,3- dithiolanes. The obtained 1,3-dithiolanes, by treatment with an equimolar amount of TBAF in a one-pot procedure, are converted in high yields into hetaryl/aryl-substituted ethenes or dibenzofulvenes, respectively, via a cycloreversion reaction of the intermediate 1,3-dithiolane carbanion. The presented protocol offers a new, highly efficient approach to tetrasubstituted ethenes and dibenzofulvenes bearing aryl and/or hetaryl substituents.

Lewis-acid-catalyzed reactions of 2-substituted cyclopropane 1,1-dicarboxylates with thioketones are described. Highly substituted tetrahydrothiophenes with two adjacent quaternary carbon atoms were obtained in a stereospecific manner under mild conditions and in high yield when using AlCl3 as Lewis acid. Moreover, an intramolecular approach was successfully implemented to gain access to sulfur-bridged [n.2.1] bicyclic ring systems. Conversion of selenoketones, the heavier analogues, under similar conditions resulted in the formation of various tetrahydroselenophenes.

The cycloaddition of diphenyldiazomethane (8) to 16 thiohetones at 40°C which furnishes tetrasubstituted 2,5-dihydro-1,3,4-thiadiazoles, is followed by rapid N2 loss (see the preceding paper), with one exception: For the dihydrothiadiazole 10,

Preparation of sulfur fine chemicals from sulfur sources is described.

The invention discloses a compound taking an olefinic bond-containing seven-membered ring structure as a core, and application of the compound, and belongs to the technical field of semiconductors, wherein the structure of the compound is represented by a

We have established photochemical access to thietane or tetrahydrothiophene compounds from thiobenzophenone derivatives and acrylonitrile, wherein the product selectivity is controlled by a simple adjustment of the reagent concentration in solution. Small libraries of five-membered ring sulfur-containing compounds were prepared through a thia-Paternò-Büchi reaction, followed by a previously unknown regioselective photochemical ring enlargement reaction in a domino process or a stepwise fashion. A mechanism is proposed to rationalize this ring enlargement reaction via a carbene species provided from photoexcited thiocarbonyl compounds.

Regioselective reaction (carbophilic over thiophilic attack) of several (o-fluorophenyl)lithium reagents with carbon disulfide was achieved to furnish dithioesters in good yields after alkylation, which are useful precursors of liquid crystal compounds having a difluoromethyleneoxy (-CF2O-) group. Running the reaction in the presence of a copper(I) salt catalyst and cyclopentyl methyl ether as a solvent is optimal.

Reduction of phosphoric acid (H3PO4) or tetra-n-butylammonium bisulfate ([TBA][HSO4]) with trichlorosilane leads to the formation of the bis(trichlorosilyl)phosphide ([P(SiCl3)2]-, 1) and t

A base-promoted, efficient [3 + 2] annulation between azaoxyallyl cations and thiocarbonyls is reported for flexible access to highly functionalized thiazolidin-4-one derivatives in good to excellent yields. An intriguing feature of this method is the met

A series of hydrazonoyl bromides prepared from readily available N-arylhydrazones of fluoral was used for the in situ generation of fluorinated nitrile imines. These 1,3-dipoles were efficiently trapped with aryl and hetaryl thioketones yielding fluoromet

Application in organic synthesis of Lawesson's reagent, 2,4-bis(4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane-2,4-disulfide, provides a possibility to replace an oxygen atom for a sulfur atom in the carbonyl group of ketones, esters, amides, in ether group, and also either to induce a rearrangement of the initial structure of organic compounds with or without inclusion of sulfur atoms or to lead to the formation of various types of organophosphorus compounds. The formed organosulfur compounds exhibit a wide range of biological action.

The reaction of diphenylketene (1) with aryl- and hetaryl-substituted thioketones (2) gave the corresponding 3,3,4,4-tetraarylthietan-2-ones (3) in good yields. Remarkably, the reactions with bis-hetaryl-substituted thioketones occurred significantly faster compared with those involving the bis-aryl-substituted thioketones. The structure of compound 3c has been established by X-ray crystallography.

Dihetaryl thioketones react with thiocarbonyl ylides to give 1,3-dithiolanes in high yields. No competitive side reactions of the thiocarbonyl ylides were observed, evidencing the 'superdipolarophilic' character of this less-known group of thioketones. De

The first systematic study of the thermal rearrangement/fragmentation of 5,5-disubstituted 1,4,2-oxathiazoles into isothiocyanates is reported. Structure-activity relationships reveal that the choice of substituent at the 5-position of the 1,4,2-oxathiazoles is the predominant factor to influence the ease of fragmentation.

A novel thionation protocol for amide compounds, with the system rhodanine/secondary amine has been discovered. Clean and efficient synthesis of a variety of thioamides can be achieved through this simple and convenient method using MCM-41 mesoporous silica as an acid catalyst. For this purpose we have synthesized MCM-41 silica and characterized by using an array of sophisticated analytical techniques like BET, HR TEM, EDX, XRD, 29Si MAS NMR and FTIR. This reaction is therefore a very neat example of a functional group interconversion.

A facile route has been developed for the preparation of a new family of contorted 1.2,3.4,7.8,9.10-tetrabenzocoronenes (TBCs). A two-step cyclization reaction, i.e., oxidative photocyclization followed by FeCl3-mediated intramolecular cyclodehydrogenation, was carried out on the olefin precursors to obtain the final TBC compounds. These new TBC molecules have contorted conformation due to steric overcrowding as disclosed by single-crystal crystallographic analysis. Nevertheless, they showed extended π-conjugation compared with coronene and exhibited strong aggregation in solution. The thermal behavior and self-assembly of TBC-C8 in solid were studied by a combination of thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), powder X-ray diffraction (XRD), scanning electron microscope (SEM), and transmission electron microscope (TEM). Compound TBC-C8 showed very good thermal and photostability and exhibited long-range ordered π-stacking in the bulk state. Moreover, uniform nanofibers with tens of micrometer length are formed in the drop-casted thin films. TBC-C8 also possesses a desirable HOMO energy level (-5.10 eV), which allows efficient charge injection from electrodes such as gold electrode. The charge carrier mobilities were determined by using the space-charge limited-current (SCLC) technique and high average hole mobility of 0.61 cm2 V-1 s-1 was obtained for TBC-C8.

Cycloreversion (CR) of thietane radical cations leads to formation of thiobenzophenone and the corresponding alkenes, eventually followed by secondary [4 + 2] cycloaddition. Final product distribution depends on the ability of fragments to escape from ion

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(Chemical Equation Presented) A novel thionation protocol for carbonyl compounds, with the system PSCl3/H2O/Et3N has been discovered. Clean, rapid, and efficient synthesis of a variety of thiocarbonyl compounds such as thioamides, thiolactams, thioketones, thioxanthones, and thioacridone can be achieved through this simple and convenient method under solventless condition with microwave irradiation.

The use of a thiobenzophenone as a self-indicating linker in the polymer-supported synthesis of isothiocyanates via a traceless 'catch and release' strategy is reported. Isothiocyanates were furnished via 1,3-dipolar cycloaddition of nitrile oxides with the polymer-supported thiobenzophenone linker, followed by Lewis acid-assisted fragmentation of the resulting polymer-supported oxathiazole.

The reaction of (trimethylsilyl)diazomethane with methyl (diethoxyphosphonyl)dithioformate (2), after elimination of N2 at -35°C, yields the 4,5-bis(trimethylsilyl)-l,3-dithiolane-2-phosphonate (8). This product is the result of the dimerizatio

A fluorous analogue of Lawesson's reagent for thionation of carbonyl compounds has been developed and its use demonstrated on a series of amides, esters, and ketones. The separation of the Lawesson's reagent-derived byproducts can be achieved by a simple fluorous solid-phase extraction.

The reactions of α-diazocamphor (6) with aromatic thioketones (9a-d) in dichloromethane at room temperature afforded mixtures of the stereoisomeric spirocyclic thiiranes (10) and (11). A reaction mechanism via [2+3] cycloaddition to give the spirocyclic 2,5-dihydro-1,3,4-thiadiazoles (13) and (14), subsequent elimination of nitrogen and 1,3-dipolar electrocyclization of the intermediate thiocarbonyl ylide (15) is proposed. The structure of the stereoisomers (10a) and (11a) has been established by X-Ray crystallography. Desulfurization of the mixtures (10/11) with triphenylphosphane in boiling THF yielded the alkylidene derivatives (12).

A simple, efficient and new method has been developed for the synthesis of thioketones by thionation of ketones using P4S10/Al 2O3 in acetonitrile. It has been found that the P 4S10/Al2O3 combination provides a simple and convenient method for the synthesis of thioketones.

The combination of P4S10 and hexamethyldisiloxane efficiently converts esters, lactones, amides, lactams, and ketones to their corresponding thiono derivatives. In the presence of elemental sulfur, 3-oxoesters are converted to dithiolethiones by this reagent. Yields are comparable to or superior to those obtained with Lawesson's reagent. The method has the advantage that reagent-derived byproducts may be removed by a simple hydrolytic workup or by filtration through silica gel, rather than by chromatography, as required for Lawesson's reagent.

Reaction of diarylmethylenetriphenylphosphoranes with elemental sulfur followed by the addition of maleic anhydride afforded 1,2-dithiolanes in good yields. When the reaction was carried out in the presence of adamantane-2-thione, two types of 1,2,4-trithiolane were formed. Thiation of thiobenzophenones with elemental sulfur also afforded the corresponding 1,2-dithiolanes.

Reactions of diaryl thioketones with diazomethane at room temperature afford 4,4,5,5-tetraaryl-1,3-dithiolanes; the scope of this surprising 2:1 interaction has been studied for decades (Schonberg Reaction). The clue to the mechanism was our observation that the stoichiometry is 1:1 at -78 °C, and 2,5-dihydro-2,2-diaryl-1,3,4-thiadiazoles are formed as primary [2+3] cycloadducts. They lose N2 at -45 °C in first-order reactions generating diaryl thioketone S-methylides which can be intercepted by thioketones (→1,3-dithiolanes), multiple CC bonds, or acids HX. In the absence of trapping reagents, the elusive intermediates either dimerize furnishing 2,2,3,3-tetraaryl-1,4-dithianes or give rise to 2,2-diaryl-thiiranes by electrocyclization. Beyond thiobenzophenone and diazomethane, our main model reaction, the studies involve fluorene-9-thione, 4,4-dimethoxy- and 4,4- dichloro-thiobenzophenone. The ring of 2,5-dihydro-2,2-diphenyl-1,3,4- thiadiazole (8) is opened by LDA at -78 °C and derivatives of anion 12 are obtained. - In summa: The Schonberg reaction consists of two 1,3-dipolar cycloadditions, linked by a 1,3-dipolar cycloreversion.

Formula presented An expeditious, solvent-free, and high yield conversion of ketones, flavones, isoflavones, lactones, amides, and esters to the corresponding thio analogues is described utilizing Lawesson's reagent in a process that circumvents the use of dry solvents and excess of the reagent.

The reactions of sterically crowded cycloalkanethiones of type 2 with CHCl3/NaOH under phase-transfer catalysis (PTC) with benzyl(triethyl)ammonium chloride (TEBA) as catalyst afforded the corresponding 'gem.-dichlorothiiranes' of type 3 in good yields (cf. Scheme 2 and Table). The desulfurization, which, in some cases, occurred spontaneously, led to (dichloromethylidene)cycloalkanes of type 4. Similar results were obtained using Seyferth's reagent in boiling benzene. In the case of 2,2,6,6-tetramethylcyclohexanethione, reaction under PTC conditions after 3 h yielded only the corresponding dichloromethylidene derivative; on the other hand, workup after 1 h gave (2,2,6,6- tetramethylcyclohexylidene)methanethione (thioketene 9; Scheme 5).

Six α-sulfinyl phosphorus ylides 6 have been prepared and are found upon flash vacuum pyrolysis at 500°C to undergo mainly extrusion of Ph3P to give thioesters, presumably by 1,2-oxygen transfer in the initially formed sulfinyl carbenes; for α-arylsulfinyl ylides loss of Ph3PO to give additional products is also observed.

Trithiazyl trichloride 1 converts 2,5-diphenylfuran into 5-benzoyl-3-phenylisothiazole 2 regiospecifically and in high yield. This is a new ring opening of furans and a new synthesis of isothiazoles. 2,5-Bis(4-methylphenyl)furan, 3-bromo-2,5-diphenylfuran, 2,3,5-triphenylfuran, 2,5-di-tert-butylfuran and its 3-chloro and 3-bromo derivatives react in an entirely analogous manner to give the corresponding isothiazoles (55-85%) in synthetically useful, one-pot, conversions. 2,5-Diphenylthiophene reacts more slowly with the trimer 1 to give the same product, 2, as the corresponding furan, probably by oxidation of the analogous thiobenzoyl compound by the reagent, which is shown to oxidise thiobenzophenone to benzophenone very rapidly. Tetraphenylcyclopentadienone 8 reacts rapidly with the trimer to give 3,4,5,6-tetraphenyl-2(1H)-pyridone 10 (56%). Possible mechanisms in which the monomer, Cl-S≡N, is the reacting species are proposed for all of these reactions.

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Reactions of some hydrazones with disulfur dichloride were reinvestigated in the absence of a base with expectation of obtaining dithiirane or thiosulfine derivatives. However, treatment of hydrazones derived from 1-adamantyl phenyl ketone, pivalophenone, and benzophenone with disulfur dichloride gave pentathianes and hexathiepanes along with other products, while di-t-butyl ketone hydrazone gave a novel heterocyclic compound, 1,1-di-t-butyltetrathiolane, though in a low yield.

Reaction of thiobenzophenone with 2,5-norbornadiene afforded an unusual seven-membered cyclic sulfide whereas 4,4′-dimethoxythiobenzophenone reacted with 2,5-norbornadiene to afford the corresponding quinone derivative via [4+2] type cycloaddition reaction. The mechanisms of these reactions are discussed.

The pathway for the electrochemical formation of 2-benzhydrylidene-4,4-diphenyl-[1,3]oxathiolan-5-one (2), in dichloromethane tetraethylammonium bromide on graphite cathode is proposed. It involves reaction between electrogenerated diphenylketene (3), 2-bromo-2,2-diphenylacetyl bromide (1) and sulfide anion. The latter is formed from H2S generated in the anodic compartment and electrogenerated bases.

The ylides Ph3P=CAr1Ar2 1a-g (Ar = C6H5, p-C6H4Cl, p-C6H4F, m-C6H4CF3, p-C6H4OCH3, p-C6H4-CH3) were treated with elemental selenium (～80°C) to give the corresponding selenoketones Se=CAr1Ar2 2 by Staudinger-chalcogenation. Their reaction with trans,trans-2,4-hexadiene proceeds completely stereospecifically to yield the 2,2-diaryl-3,6-dihydro-cis-3,6-dimethyl-2H-selenapyrans 3. In contrast, the reactions of the selenoketones 2 with cis,trans-2,4-hexadiene proceeds stereoselectively, also giving the dihydro-cis-dimethyl-2H-selenapyrans 3 as the major products, now admixed with small amounts of the dihydro-trans-dimethyl-2H-selenapyran isomers 4. The [4 + 2] cycloaddition of 2 with cis,trans-2,4-hexadiene proceeds stereospecifically, however, when carried out at a pressure of 12 kbar, now yielding 4 as the major products along with the corresponding tetraarylethenes 8. Along with the results of additional mechanistic studies (determination of solvent and substituent effects) it can be concluded that diarylselenoketones are likely to react by means of a concerted [4 + 2] cycloaddition with very reactive conjugated dienes (such as trans,trans-2,4-hexadiene), whereas a stepwise mechanism, resulting in diene cis/trans-isomerization with subsequent mechanistic "leakage" to the concerted pathway, appears to be preferred when a much less reactive conjugated diene such as cis,trans-2,4-hexadiene is employed. The reaction of the corresponding diarylthioketones 5a-g with trans,trans- and cis,trans-2,4-hexadiene, respectively, shows an analogous behavior.

The chemical conversion of carbonyl to thiocarbonyl compound was directly achieved by the treatment of benzophenone with 2,4-do-t-butyl-6-methoxyphenyldithioxophosphorane, which was prepared by the thermolysis of the corresponding dimeric species, 1,3,2,4-dithiadiphosphetane 2,4-disulfides.

Reaction of low coordinated 2,2-diphenyl-1-(2,4,6-tri-t-butylphenyl)phosphaethene with elemental sulfur afforded the corresponding 1,2-thiaphosphirane 2-sulfide 6 via methylene(thioxo)phosphorane 5.Desulfurization reaction of 6 gave the corresponding thia

Thermolysis of 1,3,4-oxathiazol-2-ones 3 in the presence of thiocarbonyl compounds gives modest to good yields of the little-known 5H-1,4,2-dithiazoles 1, the reaction being successful with diaryl, aryl alkyl and dialkyl ketones, and thiono esters, but failing with dithio esters and tertiary thioamides.The influence of substituents is discussed.Solvolysis of 5-ethoxy-5H-1,4,2-dithiazoles, derived from thiono esters, with perchloric acid in acetic anhydride gives high yields of 3,5-diaryl-1,4,2-dithiazolium salts 9.

Treatment of bis(trimethylsilyl) sulfide with CoCl2 * 6 H2O in the presence of aldehydes affords the corresponding thiocarbonyl analogues which can be trapped to avoid polymerization.The sulfurization reaction also takes place in the presence of TfOSiMe3, in which case, besides thioaldehydes, thioketones may be obtained in satisfactory yields.When thioaldehydes are generated with the CoCl2 * 6 H2O method the Diels-Alder reaction with cyclohexadiene occurs with very high selectivity in favor of the endo isomer, whereas when the TfOSiMe3-based method is employed, the stereochemistry of the cycloadduct can be conveniently selected toward endo or exo by varying the molar ratio of the sulfurating agent.

Sulfurization of nonenolizable diketones 1a-d by Lawesson's reagent (LR) and boron trisulfide reagent (B2S3) was investigated.Sulfurization of 1,4-diketone 1a with LR at 50 deg C in benzene affords disulfide 2 (23percent) and 1,3-dithietane 4a (70percent)

A novel nucleophilic catalysis for the desulfurization of thiiranes is described.Triphenylthiirane is quantitatively converted to triphenylethylene by some molpercent sodium thiophenoxide or other thiolates in DMSO at 35 deg C.A rapid initial reaction is retarded by the eliminated sulfur leading to a pseudo-first-order reaction under quasi-stationary conditions.The suggested mechanism is based on structure-rate relationships. - The thiolate-catalyzed reaction of cis-2,3-diphenylthiirane is exceptional in furnishing equimolar quantities of cis-stilbene and 3,4,6,7-tetraphenyl-1,2,5-trithiepane (2 diastereoisomers with bilateral symmetry); mechanistic implications - thiolate attack on sulfur or C-atom of thiirane - are discussed. - Desulfurization of 2,2-diphenylthiirane by thiobenzophenone or other thioketones gives access to thiocarbonyl S-sulfides ("thiosulfines") which are intercepted by 1,3-cycloadditions to activated acetylenes or to thiones.

Bis(9-borabicyclononane reacts with sulfur to give the bis(1,5-cyclooctanediylboryl)monosulfide (1) in high yield.The (9-BBN)2disulfide 2 is easily prepared from 1 with sulfur. 2, which can also be obtained from 9-Iodo-9-BBN with sulfur, reacts wit

The reactive (ar)aliphatic thioketones 3a-c are generated by cycloreversion of the anions 2 of 1,3-dithiolane-4,5-dicarboxylates 1 and are trapped by mesitonitrile oxide (5) in a 1,3-dipolar cycloaddition to give 7.From the fragmentation of anions 12 of 1,3-dithiolane 1,1-dioxides 11, thiobenzophenone (3d) and thiocamphor (3e) are isolated, wheras thioketones 3a,c with α-hydrogen are deprotonated in situ to provide enethiolates 13.Anions 13 add nitrile oxide 5 to yield thiohydroximates 8.

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After deprotonation, saturated five-membered heterocyclic rings give a facile (3+2) cycloreversion.This approach is employed in syntheses of ketenes, thioaldehydes, thioketones, thioketenes and a thioquinone at low temperature.These highly reactive double-bond systems are usually trapped in situ using (2+2), (2+3), or (2+4) cycloadditions to give various types of heterocycles.

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