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Photochemical processes enable spatial and temporal control of reactions, which can be implemented as an accurate external control approach in both polymer synthesis and materials applications. "Click" reactions have also been employed as efficient tools

A ligand-free, CuI-catalyzed protocol was developed for the one-step preparation of Michael adducts of aromatic thiols in high yields by reacting a mixture of an aryl halide and an electron-deficient alkene with sodium iso-propyl xanthogenate.

In this article we report a non-odorous protocol for the high yield formation of aryl-alkyl sulfides by the reaction of aryl iodides, bromides and boronic acids with elemental sulfur and electron-deficient alkenes, catalyzed by copper ferrite nanoparticles. The catalyst was easily separated using an external magnetic bar and recycled for subsequent runs, its catalytic activity being preserved.

Borontribromide (BBr3) is a well-known demethylating agent. The current investigation was focused on a new application of borontribromide as a C-C bond forming agent in cyclic ketones. In this study, borontribromide mediated C-C bond formation reactions of tetralones, chromenone, thiochromenone and indanones were explored. A methoxy group containing ketones showed selective C-C bond formation reaction instead of demethylation of the methoxy group. MM2 steric energy calculations for the final products showed that the reaction favored the formation of exo- or endo-cyclic double bond containing products, depending upon their low MM2 steric energy in a specific frame structure, as observed in X-ray crystallography. A comprehensive crystallographic and pi-stacking analysis of product 10a demonstrated the formation of 10a as an enantiomeric mixture, and its centre of inversion was stabilized by a set of three unique pi-pi interactions.

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.

A highly efficient organocatalytic asymmetric SMA reaction of hexafluoroisopropyl α,β-unsaturated esters has been developed. Introducing electron-withdrawing hexafluoroisopropyl ester is crucial to enhancing the electrophilicity of unsaturated esters as S

The hetero-Michael reactions among various oxygen, sulfur, and nitrogen nucleophiles and ,-unsaturated compounds were carried out in the presence of catalytic amounts of o-benzenedisulfonimide as Brnsted acid organocatalyst. The reaction conditions were very mild, and the yields of target products were good. The catalyst was easily recovered and purified, ready to be used in further reactions. This ability grants economic and ecological advantages. Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications to view the free supplemental file.

1-Methylimidazolium trifluoroacetate ([Hmim]-TFA) is reported as a cost-effective catalyst for a simple and environmentally benign hetero-Michael reaction. [Hmim]TFA works both as reaction medium and catalyst. The reaction is applicable to various aromatic sulfur and nitrogen nucleophiles. This method has advantages such as high yields, short reaction time, and simple workup. The catalyst could be recycled several times without any loss of activity.

Diaryl disulfides were reduced efficiently by a Zn/Cp2TiCl 2 system at room temperature in dry THF to give the corresponding nucleophilic sulfur anion-titanocene complex, followed by reaction with α, β-unsaturated esters (ketones or nitriles) to afford the corresponding β-arylthioesters(ketone or nitrile) in good yields.

A heterogeneous Lewis acid catalytic system has been developed by incorporating gadolinium triflate on to poly[styrene-co-(1-((4-vinylphenyl)methyl)-3-methylimidazolium) tetrafluoroborate] (1-Gd(OTf)3), and the catalytic activity of this system has been examined for Michael additions of amines and thiols to α,β-unsaturated esters and acrylonitrile. The reactions proceed in moderate to excellent yields in the presence of catalytic system 1-Gd(OTf)3. The catalytic system could be efficiently recycled and reused.

Perchloric acid adsorbed on silica gel (HClO4X/SiO2) has been found to be a highly efficient and versatile catalyst for the Michael addition of thiols to a wide variety of conjugated alkenes such as α,α-unsaturated ketones, carboxylic esters, nitriles, amides and chalcones in dichloromethane or methanol at room temperature. The reactions are completed within 2-20 min in high yields. Some of the additional advantages are: no aqueous work-up is necessary, and the catalyst is also reusable. Moreover, the solid product can be obtained without chromatographic separation. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.

Liquid/liquid separation after monophasic reactions is a viable way to use and recover polysiloxane-supported catalysts. The Royal Society of Chemistry 2006.

An easily accessible and inexpensive room temperature ionic liquid, 1-pentyl-3-methylimidazolium bromide, [pmIm]Br efficiently catalyzes the reaction of alkyl halides or acyl halides with thiols without any solvent at room temperature leading to the synthesis of thioethers and thioesters in high yields. This reaction has also been extended for the preparation of dithianes and transthioetherification. The ionic liquid is recovered and recycled for subsequent runs.

The cross-coupling of aliphatic and aromatic thiols and aryl bromides/triflates mediated by a Pd2(dba)3/Xantphos catalytic system in refluxing xylene (140°C) affords the corresponding aryl thioethers in good to excellent yields.

Disulfide has been reduced by cerium trichloride and samarium in tetrahydrofuran to produce samarium thiolates. The "living" species reacts smoothly with α,β-unsaturated esters(nitriles) to afford β-thioesters(nitrile) under mild and neutral conditions. The new thiolate anion also reacts with acyl halides, anhydrides and alkyl or benzyl halides to give thioesters and sulfides, respectively.

The 1,4-conjugate addition of primary, secondary and aromatic amines, thiols, and carbamate to α,β-unsaturated compounds mediated by a catalytic amount (0.5 mol%) of RuCl3 in poly(ethylene glycol) (PEG) provides the desired β-substituted carbonyls in high yields. In particular, we found that primary aliphatic and aromatic amines produced the single adducts as the sole products in very high yields with RuCl3-PEG. RuCl 3-PEG was readily recycled via solvent precipitation with efficient recyclability as evidenced by high yields. Its properties of low sensitivity toward moisture and oxygen, high tolerance of different functional groups, and efficient recyclability make RuCl3-PEG suitable for both laboratory and industrial scale synthesis of β-substituted carbonyls. Georg Thieme Verlag Stuttgart.

3-Phenoxypropanoic acid (1), 3-(phenylthio)propanoic acid (2), and 4-phenylbutanoic acid (3) were pyrolysed between 520 and 682 K. Analysis of the pyrolysates showed the elimination products to be acrylic acid and the corresponding arene. Pyrolysis of ethyl 3-phenoxypropanoate (4) and its methyl analogue (5), ethyl 3-(phenylthio)propanoate (6) and its methyl counterpart (7), and 3-phenoxypropane nitrile (8) were also investigated between 617 and 737 K. The thermal gas-phase elimination kinetics and product analysis are compatible with a thermal retro-Michael reaction pathway involving a four-membered cyclic transition state.

Development of new odorless thiols (dodecanethiol, 4-n- heptylphenylmethanethiol, 4-trimethylsilylphenylmethanethiol, 4-trimethylsilylbenzenethiol) and an odorless sulfide (1-methylsulfanyldodecane) and their applications to dealkylation, Michael addition, Swern oxidation, and Corey-Kim oxidation are described.

A mild, selective, and high-yielding method for oxidation of sulfides to sulfoxides using IBX and tetraethylammonium bromide in a variety of solvents is described. The method offers the advantage of short reaction times, no over-oxidation to sulfones, and compatibility to a wide range of functional groups.

The regiochemistry of the Michael addition of thiols to unsymmetrical fumaric derivatives was investigated. Conjugate addition of thiols to unsymmetrical fumaric diester was well controlled by the presence of lithium cation and one of the two possible regioisomers was prepared in a highly selective manner. Fumaric ester amides underwent the regioselective Michael addition that was controlled by the presence or absence of the base; either of the regioisomers was prepared as an almost diastereomerically pure form. The present control of the regiochemistry can be explained by the factors of change of active site for the addition by the coordination or non-coordination of proton or lithium cation to the carbonyls. To clarify the origin of the regioselectivity, the relative rates of the conjugate addition of thiol to acrylate derivatives were measured under competitive conditions. Ethyl acrylate reacted with thiol faster than tert-butyl acrylate and the rate difference was enhanced by the presence of lithium cation. In the presence of base, ethyl acrylate gave the adducts much faster than acrylamide, while under non-basic conditions acrylamide showed higher reactivity than the ester. This regioselectivity was also observed in the Michael/aldol reaction and multi-substituted γ-butyrolactones were prepared in a stereoselective manner. The thio groups introduced here served as a leaving group and a convenient stereoselective synthesis of β-, γ- and δ-lactams was developed.

Syntheses and odor tests of the trialkylsilylated benzyl mercaptans and benzenethiols have revealed that the trimethylsilyl substituent on the benzene ring has a remarkable effect in reducing the foul smell of the parent benzyl mercaptan and benzenethiol.

The S-S bond in disulfides was reduced by the Zn/ZrCl4 system in THF to produce sulfur anions, which react with alkyl halides, α,β-unsaturated esters and acyl chlorides or anhydrides to afford unsymmetrical sulfides, thioesters and β-thioesters, respectively.

The synthesis of a range of 3-(phenylsulfonimidoyl)propanoate derivatives is described. A number of strategies for the imination of the key sulfoxide methyl 3-(penylsulfinyl)propanoate are discussed including the use of O-(mesitylsulfonyl)hydroxylamine (M

In a domino-type reaction sequence, the redox chemistry of [BnNEt3]2MoS4 is exploited in forming and cleaving disulfides(see scheme). This strategy has been utilized effectively in a one-pot tandem sulfurtransfer/reduction

Promoted by low-valent titanium, aryl sulfonyl chlorides react with α,β-unsaturated esters in THF to give β-arylthio propanoic esters in moderate to good yields.

Free radical-mediated carboxylation is achieved by treatment of alkyl iodides with S-phenyl chlorothioformate and bis(tributyltin) with irradiation at 300 nm.

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Ethyl (substituted phenylthio) acetate and propionate derivatives have been synthesised, their structures were proved by IR, NMR and mass spectra.Key words: Arylthioacetates; arylthiopropionates; NMR- and mass spectra

Novel heteroarotinoid compositions characterized by the formulae: STR1 where: X is S or O; OAc is the acetate group STR2 and R is --H, --OH, --OCH3, or --OC2 H5 and includes STR3 for formulae (1) and (2). Such compositions exhibit activity as anticancer agents.

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A 5-step synthesis of terminally unsaturated β-fluoro-α,β-unsaturated esters and nitriles 1 is described. Substantial amounts of a deoxygenative side reaction were observed during the key fluoro-Pummerer rearrangement step in the routes leading to the nitriles 1c and 1d.

Novel heteroarotinoid compositions characterized by the formulae: STR1 where: X is S or O; OAc is the acetate group STR2 and R is --H, --OH, --OCH3, or --OC2 H5 and includes STR3 for formulae (1) and (2). Such compositions exhibit activity as anticancer agents.

Novel heteroarotinoid compositions characterized by the formulae: STR1 where R is H, CH3 or C2 H5 and X is S, S O, O, NCH3, Si(CH3)2, N+ (H)CH3 [Cl- ], N+ (H)CH3 [Br- ] or N+ (alkyl) CH3 [Cl- or Br-) where alkyl is CH3, C2 H5, CH2 =CHCH2 or C6 H5 CH2. Such compositions exhibit activity as anticancer agents.

There is reported the first four members of heteroarotinoids, the names of which are ethyl (E)-p-benzoate (1b), ethyl (E)-p-benzoate (1c), ethyl (E)-p-benzoate (1d), and (E)-p-benzoic acid (1e).IR, 1H NMR and 13C NMR data have been recorded for each compound and support the structural assignments.To provide a firm basis for comparison purposes of future analogues, an X-ray analysis was performed on asingle crystal of ethyl (E)-p-benzoate (1b) and a precursor 4,4-dimethylthiochroman-6-yl methyl ketone 1,1-dioxide (18).These data for the heteroarotinoid 1b revealed that the two aryl ring systems were nearly perpendicular in each of the two molecules present in the unit cell (86.37 deg and 84.17 deg, respectively).The space group for both molecules was P1 in triclinic systems.Unit cell dimensions (at 15 deg C) are as follows: for 1b, a = 20.568 (6) Angstroem, b = 14.760 (3) Angstroem, c = 7.679 (2) Angstroem, α = 113.33 (2) deg, β = 79.45 (2) deg, γ = 79.98 (2) deg, Z = 4; for 18, a = 9.292 (5) Angstroem, b = 9.291 (5) Angstroem, c = 7.951 (3) Angstroem, α = 102.16 (3) deg, β = 77.49 (3) deg, γ = 79.60 (4) deg, Z = 2.The sulfur containing ring is in a distorted half-chair in 1b and the methyl carbon C(12) is shown to be trans to H(13) at the C(11)-C(13) bond.The biological activity of these arotinoids was determined in the tracheal organ culture asssay and compared with trans-retinoic acid for ability to reverse keratinization in vitamin A deficient hamsters.The ester 1b displayed activity about one-half log unit less than of the ref erence while 1c and 1e had activity nearly one log until less than trans-retinoic acid.The sulfoxide was the least active of the heteroretinoids.

The β-carbon of α,β-unsaturated ketones, esters, lactones, and nitriles can be oxidatively functionalized in a regiospecific manner in a simple sequence of reactions.Michael addition of thiophenol followed by oxidation with N-chlorosuccinimide gives chloro sulfides that readily lose HCl to give 3-phenylthio enones, acrylates, and other vinyl derivatives.