884-09-3

We have developed a palladium-catalyzed thiocarbonylation through the reaction of a σ-alkyl palladium intermediate with carbon monoxide and a triisopropylsilyl (TIPS) thioether. The use of CsF, (IPr)Pd(allyl)Cl [IPr =1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene], CO, and a TIPS thioether in THF are key to obtaining alkyl and aryl thioesters in high yields. The yield of the palladium-catalyzed thiocarbonylation depended on the structure of the substrate; indoline-2-one derivatives were formed faster than indoline derivatives. The reactions of benzoyl and hydrocinnamoyl fluorides with TIPSSPh and CsF also gave the corresponding thioesters.

The method takes sodium sulfinate and acyl chloride as raw materials and utilizes 2, 6 - dimethyl -1, 4 - dihydro -3, 5 - pyridine dicarboxylic acid diethyl ester and an organic alkali catalytic system to cross-couple sulfur radicals and acyl radicals und

A practical and efficient approach for the synthesis of selenol and thiol esters is described via the reaction of acyl chlorides with diselenides or disulfides in the presence of Zn dust catalyzed by inexpensive CoCl2·6H2O This proto

Decarbonylative synthesis of thioethers from thioesters proceeds in the presence of a catalytic amount of [Rh(cod)Cl]2 (2 mol %). The protocol represents the first Rh-catalyzed decarbonylative thioetherification of thioesters to yield valuable thioethers. Notable features include the absence of phosphine ligands, inorganic bases, and other additives and excellent group tolerance to aryl chlorides and bromides that are problematic using other metals to promote decarbonylation. Gram scale synthesis, late-stage pharmaceutical derivatization, and orthogonal site-selective cross-couplings by C-S/C-Br cleavage are reported.

We report the palladium-catalyzed double-decarbonylative synthesis of aryl thioethers by an aryl exchange reaction between amides and thioesters. In this method, amides serve as aryl donors and thioesters are sulfide donors, enabling the synthesis of valuable aryl sulfides. The use of Pd/Xantphos without any additives has been identified as the catalytic system promoting the aryl exchange by C(O)-N/C(O)-S cleavages. The method is amenable to a wide variety of amides and sulfides.

Disclosed herein are embodiments of a donor compound that releases H2S by reacting with a reactive compound. The donor compound embodiments described herein can be used to deliver H2S to a subject or a sample and further can be used to administer therapeutic agents. The donor compound embodiments also can facilitate bioconjugation. Methods of making and using the donor compound embodiments also are disclosed.

The development of efficient methods for facilitating N-C(O) bond activation in amides is an important objective in organic synthesis that permits the manipulation of the traditionally unreactive amide bonds. Herein, we report a comparative evaluation of a series of cyclic amides as activating groups in amide N-C(O) bond cross-coupling. Evaluation of N-acyl-imides, N-acyl-lactams, and N-acyl-oxazolidinones bearing five- and six-membered rings using Pd(II)-NHC and Pd-phosphine systems reveals the relative reactivity order of N-activating groups in Suzuki-Miyaura cross-coupling. The reactivity of activated phenolic esters and thioesters is evaluated for comparison in O-C(O) and S-C(O) cross-coupling under the same reaction conditions. Most notably, the study reveals N-acyl-δ-valerolactams as a highly effective class of mono-N-acyl-activated amide precursors in cross-coupling. The X-ray structure of the model N-acyl-δ-valerolactam is characterized by an additive Winkler-Dunitz distortion parameter ?(τ+χN) of 54.0°, placing this amide in a medium distortion range of twisted amides. Computational studies provide insight into the structural and energetic parameters of the amide bond, including amidic resonance, N/O-protonation aptitude, and the rotational barrier around the N-C(O) axis. This class of N-acyl-lactams will be a valuable addition to the growing portfolio of amide electrophiles for cross-coupling reactions by acyl-metal intermediates.

Abstract: An unprecedented metal-, halogen- and solvent-free, MSAA-promoted S-carbonylation of thiols with feedstock acids has been developed. This new transformation provides an efficient and atom-economic strategy for the synthesis of thioesters in a single operation from readily available and inexpensive starting materials. The reaction avoids the use of expensive and hazardous coupling reagents, bases and generates water as the only by-product, thus making this chemical synthetic process more viable, environment-friendly and contributing towards sustainable chemistry. Graphic abstract: [Figure not available: see fulltext.].

An alternative thioesterification reaction via copper-catalyzed oxidative coupling of readily available aroylhydrazides with disulfides is developed, in which oxidative expulsion of N2 overcomes the activation barrier between the carboxylic acid derivativ

We report conversion of esters to thioestersviaselective C-O bond cleavage/weak C-S bond formation under transition-metal-free conditions. The method is notable for a general and practical transition-metal-free system, broad substrate scope and excellent functional group tolerance. The strategy was successfully deployed in late-stage thioesterification, site-selective cross-coupling/thioesterification/decarbonylation and easy-to-handle gram scale thioesterification. Selectivity and computational studies were performed to gain insight into the formation of weak C-S bonds by C-O bond cleavage, which contrasts with the traditional trend of nucleophilic additions to carboxylic acid derivatives.

Herein reported is a nickel-catalyzed reductive aryl thiocarbonylation of alkene via thioester group transfer strategy by using simple and readily available thioesters. In contrast to traditional activation of weaker C(acyl)-S bond, the C(acyl)-C bond of

An air-stable μ-oxo-bridged binuclear Lewis acid of titanium(IV) salophen perfluorobutanesulfonate [{Ti(salophen)H2O}2O][OSO2C4F9]2 (1) was successfully synthesized by the reaction of TiIV(salophen)Cl2 with AgOSO2C4F9 and characterized by techniques such as IR, NMR and HRMS. This complex was stable open to air over a year, and exhibited good thermal stability and high solubility in polar organic solvents. The complex also had relatively strong acidity with a strength of 0.8 Ho ≤ 3.3, and showed high catalytic efficiency towards various C–S and C–Se bond formations in the presence of zinc power. This catalytic system affords a mild and efficient approach to synthesis of thio- and selenoesters, α-arylthio- and seleno-carbonyl compounds, and thio- and selenoethers.

The invention discloses a method for preparing a benzoic acid-S-phenyl ester compound shown as a formula (IV) through cuprous catalysis. The preparation method comprises the following steps of: preparing a reaction product from a benzaldehyde compound shown as a formula (I), elemental sulfur shown as a formula (II) and an iodobenzene compound shown as a formula (III) by using cuprous iodide as a catalyst, tetraethylammonium bromide as an alkali and N, N-dimethylformamide as a medium, and carrying out post-treatment on the reaction product to obtain the benzoic acid-S-phenyl ester compound, wherein the formulas are described in the specification. The method is efficient in chemical agent and low in cost; and the catalytic system has wide adaptability and is suitable for large-scale production of chemical intermediates.

A simple and efficient method has been developed for the synthesis of thioesters from carboxylic acids and thiols using N,N'-diisopropylcarbodiimide (DIC). The reactions were carried out in water as an environmentally friendly and green solvent. The devel

An interesting procedure for thioester synthesis via nickel-catalyzed thiocarbonylation of arylboronic acid with sulfonyl chlorides as the sulfur source has been explored. Using Mo(CO)6 as a solid CO surrogate and reductant, a broad range of thioesters were obtained in moderate to good yields with good functional group tolerance.

The direct nucleophilic addition to amides represents an attractive methodology in organic synthesis that tackles amidic resonance by ground-state destabilization. This approach has been recently accomplished with carbon, nitrogen and oxygen nucleophiles.

A convenient visible-light photoredox catalysis has been developed for the synthesis of thioesters from two readily available starting materials: acid chlorides and sodium sulfinates. The facile generation of acyl radical species under the visible light photoredox conditions allows the formation of thiyl radical species from sodium sulfinates via multiple single electron transfer reactions, where the final acyl radical-thiyl radical coupling has been accomplished. The direct radical-radical coupling strategy offers a mild and controlled photochemical approach to important synthetic building blocks such as thioesters.

A method for Ni-catalyzed controlled decarbonylation of α-ketothioesters is described. Mono- and double-decarbonylations, which gave thioesters and thioethers, respectively, were selectively achieved by changing the ligand. A fundamental study of Ni-catalyzed decarbonylation of α-ketothioesters is presented.

An efficient and user-friendly palladium(II) precatalyst, POxAP (post-oxidative-addition precatalyst), was identified for use in Fukuyama cross-coupling reactions. Suitable for storage under air, the POxAP precatalyst allowed reaction between thioesters and organozinc reagents with turnover numbers of ～90000. A series of 23 ketones were obtained with yields ranging from 53 to 99%. As proof of efficacy, an alternative approach was developed for the synthesis of a key precursor of the natural product isoprekinamycin.

A general, highly selective method for decarbonylative thioetherification of aryl thioesters by C-S cleavage is reported. These reactions are promoted by a commercially-available, user-friendly, inexpensive, air- and moisture-stable nickel precatalyst. The process occurs with broad functional group tolerance, including free anilines, cyanides, ketones, halides and aryl esters, to efficiently generate thioethers using ubiquitous carboxylic acids as ultimate cross-coupling precursors (cf. conventional aryl halides or pseudohalides). Selectivity studies and site-selective orthogonal cross-coupling/thioetherification are described. This thioester activation/coupling has been highlighted in the expedient synthesis of biorelevant drug analogue. In light of the synthetic utility of thioethers and Ni(ii) precatalysts, we anticipate that this user-friendly method will be of broad interest.

Efficient TBHP/R4N+X– promoted hydroaroylations of dialkyl azo-1,2-dicarboxylates with methyl arenes, aldehydes, aryl methanols and arylmethyl chlorides are described. These oxidation/oxygenation and hydroaroylation processes were carried out by tert-butyl hydroperoxide as terminal oxidant/oxygen source, and were catalyzed by tetrabutylammonium bromide and tricaprylmethylammonium chloride as the driving force. During this investigation, all these hydroaroylating sources were found to be highly efficient reagents without the need of any transition-metal.

A practical direct method for the direct preparation of esters and thioesters from aldehydes is described. Esters and thioesters were synthesized by oxidative esterification and thioesterification via in situ generated acyl bromide intermediates, which were used to react with various alcohols and thiols. The esterification and thioesterification were readily performed in the presence of dibromoisocyanuric acid in dichloromethane, without any metal catalysts and under mild conditions. By using this reaction protocol, various esters and thioesters were prepared in high yields. This effective method offers a promising approach for the facile esterification and thioesterification of aldehydes.

The invention provides a preparation method of a novel ionic binuclear Schiff base titanium complex and a synthetic method of applying the novel ionic binuclear Schiff base titanium complex to catalyze zinc powder and reduce disulfide or selenide to prepare sulfo(seleno) ester and dissymmetric sulfoether(selenide). The complex is a cationic binuclear Schiff base titanium complex, wherein titaniumatoms are bridged by oxygen atoms and are coordinated with a Schiff base ligand and a hydrone, and an ionic bond is formed by a cation part and an anion part of whole Schiff base titanium. The ionic binuclear Schiff base titanium complex is used as a catalyst, the zinc powder is used as a reducer, the disulfide(selenide) can be reduced and fractured, and the disulfide(selenide) can further and respectively react with anhydride, an alpha-bromo carbonyl compound and bromoalkane to prepare the sulfo(seleno) ester and the dissymmetric sulfoether(selenide). According to the preparation method provided by the invention, the defects that traditional lewis acid halide is deliquescent, an absolute solvent is used, conditions are strict and the like are overcome; an effective path for reducing the disulfide or selenide to prepare the sulfo(seleno) ester and the dissymmetric sulfoether(selenide) is provided, and the preparation method has the advantages of high yield, simpleness in operation andthe like.

A general, transition-metal-free, and operationally simple method for esterification of amides by a highly selective cleavage of N-C(O) bonds under exceedingly mild conditions is reported. The reaction is characterized by broad substrate scope and excellent functional group tolerance. The potential of this mild esterification is highlighted by late-stage diversification of natural products and pharmaceuticals. Conceptually, the metal-free acyl functionalization of amides represents a significant step forward as a practical alternative to ligand exchange in acylmetal intermediates.

Nucleophilic acylation of symmetrical carboxylic anhydrides has inherited limitation of reaction efficiency along with relatively poor reactivity. Traditionally, one equivalent carboxylic acid is generated during nucleophilic acylation of a symmetrical anhydride, which always limits the yield of final product to 50percent or less. This is a major drawback, which discourages the use of anhydrides for laboratory or industrial applications. Electrophilic activation of carboxylic anhydride using methanesulfonyl chloride is found to be an efficient method for nucleophilic acylation, which increases product yield by restricting the formation of corresponding acid as a side product. The developed protocol found to be a mild and high yielding methodology for one-pot nucleophilic acylation of carboxylic anhydrides with several type of N- and S-nucleophiles demonstrating appreciable functional group tolerance.

To explore further the practical uses of highly active manganese (Mn?), a variety of alcohols were treated with Mn?, and the resulting complexes were coupled with acid chlorides and/or acetic anhydride in the absence of any extra catalyst. The subsequent reactions took place smoothly under mild conditions, providing the corresponding O-acylation products in good to excellent isolated yields.

A novel, efficient, metal-, base- and acid-free straightforward protocol has been developed for the construction of useful thioesters. The immense catalytic potential of HFIP for promoting the thiocarbonylation of acyl halides and thiols is disclosed. HFIP was recovered with ease and reused for further reactions without any loss of reactivity. Both aryl and alkyl thiols bearing electron-donating and electron-withdrawing groups as well as aryl- and alkyl acyl halides worked well in this reaction. Inexpensive precursors, short reaction time, obviating workup, high atom economy, and gram-scale preparation are the significant features of the developed eco-friendly route for S-carbonylation of thiols.

We report the synthesis of biaryl ketones via an unprecedented copper/silver catalyzed acylative cross-coupling of thiol esters with either an arylboronic acid or a potassium aryltrifluoroborate. This new method proceeds without a requisite Pd-catalyst and Cu(I)TC mediator, and is efficient, versatile, operationally simple, and accommodating functionally diverse thiol esters, arylboronic acids, and potassium aryltrifluoroborates.

Poly(3,4-dimethyl-5-vinylthiazolium) was synthesized from 3,4-dimethyl-5-vinylthiazole through free radical polymerization and was examined as polymer precatalysts in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) for the thioesterification of aldehydes with thiols. The poly(5-vinylthiazolium)/DBU had excellent catalytic activity and could be reused 10 times without a considerable loss of activity. To S-um up: Poly(3,4-dimethyl-5-vinylthiazolium) is examined as a polymer precatalyst in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) for the thioesterification of aldehydes with thiols. The poly(5-vinylthiazolium)/DBU system shows excellent catalytic activity and can be reused 10 times without a considerable loss of activity.

The use of PhSZnBr as sulfenylating agent in a solvent-free protocol to prepare thiol esters in excellent yields from acyl chlorides is reported. The products were efficiently obtained by grinding the neat reagents for 5 min in a mortar. DFT calculations

This work describes acylation reactions facilitated by a type of heterocycle-based acyl transfer agent, 2-acyloxypyridazinone. Reactions of 2-acyloxypyridazinone with carboxylic acids yield mixed carbonic anhydride intermediates, which are reactive and could be coupled with a wide range of substrates including acids, amines, alcohols, and thiols. The wide substrate scope, ease of operation (no additive or catalyst), storage and handling stability, and atom-efficiency from recycling the heterocycle carrier make the reported acylating agent attractive for acylation-based coupling reactions.

The rearrangement of substituted 1,4,2-oxathiazoles to nitriles in the presence of water is described. Preliminary investigations suggest that the reaction pathway proceeds via a 1,4,2-oxathiazolium intermediate, followed by trapping with water and subsequent decomposition to products. An unprecedented rearrangement of 5-phenyl-1,4,2-oxathiazoles bearing a C5 leaving group to nitriles in the presence of water is described.

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.

An efficient and recyclable imidazolium-supported benzotriazole reagent (Im-CH2-BtH) as a novel synthetic auxiliary has been synthesized and its utility as a carboxyl group activating reagent via the formation of stable imidazolium-supported acyl benzotriazoles was explored for the synthesis of amides, esters and thioesters in water under microwave conditions. The reagent was reused five times without any noticeable loss in activity. It is moisture insensitive and highly stable under thermal and aerobic conditions. The application of imidazolium-supported N-acetyl benzotriazole leads to synthesis of paracetamol on the gram scale under greener conditions in 93% yield.

This study describes our findings on a novel and cheap NiCl2 catalytic system under ligand-free conditions for the efficient thiocarbonylation, alkoxycarbonylation and amidocarbonylation reactions of aryl iodides in the presence of Cr(CO)6 as the solid source of carbon monoxide under air. A variety of aryl iodides tolerated the reaction conditions and structurally different thiols, alcohols and amines were used efficiently. The corresponding thioesters, esters and amides were obtained in good to excellent yield at atmospheric pressure under mild reaction conditions.

The reactivity of [Pd(dippe)(μ-H)]2 (1) and [(μ-dippe)Pd]2 (2) (dippe = 1,2-bis(diisopropylphosphino)ethane) toward C-S bonds in thiophene derivatives and thioethers was investigated, which led to C-S bond activation products. The thiapalladacycles derived from thiophenic substrates were fully characterized by 1H, 31P, and 13C NMR spectroscopy, elemental analysis, and X-ray diffraction. The stability of the C-S insertion products was probed by performing competition experiments which follow the thermodynamic stability order (dippe)Pd(κ2C,S-benzothiophene) (6) > (dippe)Pd(κ2C,S-dibenzothiophene) (8) > (dippe)Pd(κ2C,S-thiophene) (3). The reactivity of the thiapalladacycles with small molecules such as H2, CO, and alkynes was investigated.

A novel, efficient, and catalyst-free strategy has been initially developed for the construction of thioesters via the direct radical oxidative decarboxylation of α-keto acids with thiols, and the corresponding target products were obtained in moderate to good yields. It offers an alternative approach for the synthesis of useful diverse thioesters.

Copper-catalyzed decarboxylative coupling between α-oxocarboxylic acids and diphenyl disulfides or thiophenols is presented, which provided an effective and direct approach for the preparation of useful thioesters through C(sp2)-S bond formatio

Thiol and selenol esters were synthesized by a direct oxidative coupling reaction of aldehydes with disulfides or diselenides in ethyl acetate under metal-free conditions. Among the oxidants examined, tert-butyl peroxide (TBP) was shown to give the best results. For the substrates with both electron-donating and electron-withdrawing substituents, the reaction proceeded smoothly and gave moderate to good yields. Compared with the previous method, the present route is very simple, atom-economical and environmentally friendly. This journal is the Partner Organisations 2014.

Newly discovered boryl sulfides and N-borylthioamides are shown to serve as neutral sources of sulfur nucleophiles in substitutions reactions. For example, heating of diMe-Imd-BH(SPh)2 with benzyl bromides, primary bromides, or acid chlorides provides the corresponding thioethers or thioesters in high yields. Likewise, N-phenyltetrazole thioethers/esters are made from a readily available N-borylthionotetrazole. The formation of the boryl sulfide and its onward nucleophilic substitution can be telescoped down to a one-pot reaction whose components are an NHC-borane (NHC-BH3), a disulfide, and an electrophile.

RhH(PPh3)4 and 1,2-bis(diphenylphosphino)benzene catalyze the reaction of aryl/heteroarylmethyl ketones and aryl heteroaryl ethers giving unsymmetrical diarylmethanes containing one or two heteroarenes in high yields. The reaction do

The acylation of diselenides or disulfides with N-acylbenzotriazoles mediated by SmI2 has been achieved successfully without the presence of HMPA, and the corresponding selenolesters or thioesters have been prepared in good yields.

The acylation of alcohols, phenols, amines, and thiophenols was accomplished with 0.5 mol % of tris(pentafluorophenyl)borane [B(C 6F5)3] at ambient temperature under solvent-free condition. Major advantages of this method include high yield, short reaction time, simple procedure, compatibility with sensitive protecting groups as well as other functional groups, absence of racemization of optical active compounds, and epimerization of sugars.

A metal-free, tetraethylammonium bromide-catalyzed oxidative coupling of aldehydes or alcohols with thiophenols or disulfides has been developed. This protocol affords an efficient and inexpensive approach to the synthesis of a wide range of thioesters in high yields. Copyright

We report an efficient, fast, and environmentally friendly method for the synthesis of a wide range of thiol esters using stable diorganoyl disulfides and acyl chlorides, using CuO nanoparticles and [pmim]Br as the reductive system. This method gave good to excellent isolated yields of the desired products after only three minutes of microwave irradiation. Furthermore, by using the same green approach, we were also able to synthesize thiocarbonates bearing interesting functionalities. We report an efficient, fast, and environmentally friendly method for the synthesis of thiol esters starting from diorganoyl disulfides and acyl chlorides, and using CuO nanoparticles and [pmim]Br as the reductive system. This approach gave good to excellent isolated yields of the desired products in only three minutes under microwave irradiation. Copyright

Benzenethiol is reacted with acetic acid in a hydrogen stream over [(Mo6Cl8)Cl4(H2O) 2]·6H2O. Catalytic activity of the clusters appears above 200 °C, yielding S-phenyl thioacetate. The selectivity is 98% at 300 °C. Niobium, tantalum, and tungsten halide clusters with the same octahedral metal framework also catalyze the reaction. Benzoic acid and aliphatic carboxylic acids afford the corresponding S-phenyl carbothioates by reaction with benzenethiol. Aliphatic thiols are also S-acylated to yield the corresponding S-alkyl carbothioates. When carboxylic esters are applied to the reaction with benzenethiol over [(Nb6Cl12)Cl 2(H2O)4]·4H2O at 450 °C, the sterically unhindered moiety of the ester is incorporated into the products: S-phenyl thioacetate or methyl phenyl sulfide is obtained selectively. A Br?nsted acid site developed on the cluster complex by thermal activation is the active site of the catalyst. Hence, solid acids such as silica-alumina, zeolites, and heteropoly acids that are stable above 200 °C also catalyze these reactions.

A general protocol for the Pd-catalyzed thiocarbonylation of aryl iodides with stoichiometric carbon monoxide has been established employing a catalytic system composed of Pd(OAc)2 and DPEphos with low catalyst loading (1 mol %). Both electron-rich and -deficient aryl iodides proved effective for these couplings with aryl and alkyl thiols. The choice of the metal ligands and the solvent system was crucial for the efficiency and chemoselectivity of these transformations.

S-aryl thioacetates can be prepared by reaction of inexpensive potassium thioacetate with both electron-rich and electron-poor aryl iodides under a base-free copper/ligand catalytic system. CuI as copper source affords S-aryl thioacetates in good to excellent yields, by using 1,10-phenanthroline as a ligand in toluene at 100°C after 24 h. Under microwave irradiation the time was drastically reduced to 2 h. Both procedures are simple and involve a low-cost catalytic system. This methodology was also applied to the "one-pot" synthesis of target heterocycles, such as 3H-benzo[c][1,2]dithiol-3-one and 2-methylbenzothiazole, alkyl aryl sulfides, diaryl disulfides and asymmetric diaryl sulfides in good yields.

An efficient N-heterocyclic carbene (NHC)-catalyzed direct thioesterification of aldehydes and α,β-unsaturated aldehydes (enals) with diaryl disulfides is reported. The protocol involves carbonyl umpolung reactivity of aldehydes and enals in which the car

The NHC-catalyzed thioesterification of aromatic or aliphatic aldehydes with a range of thiols was developed in the presence of a stoichiometric amount of an organic oxidant. Among the oxidants examined, phenazine was shown to give the best results in terms of chemical yield and compatibility with thiols.