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Organic disulfanes (also named disulfides) play a vital role in chemistry and biology.1–4 In particular, unsymmetrical disulfanes are a class of important molecules with bioactivities,1–4 such as a...

Bioassay-guided fractionation of the fruit powder of Graviola (Annona muricata) was continued to be conducted and yielded three more novel bioactive compounds: C-35 annonaceous acetogenins, muricins M and N, and C-37 annonaceous acetogenins, muricenin. They all contain a mono-tetrahydrofuran ring and four hydroxyl groups. The structures were elucidated by spectral methods and chemical modification after isolation via open column chromatographic separation and HPLC purification. Especially, murices M and N demonstrated more potent anti-proliferative activities against human prostate cancer PC-3 cells.

An iron-catalyzed practical synthesis of 2-trifluoromethylarylimidazoles through condensation of o -arylenediamines and hexafluoroacetylacetone followed by intramolecular addition and C–C bond cleavage in one-pot has been developed. A series of title compounds were obtained with up to 99% yield. This method is quite practical and suitable for scalable preparation due to simple experimental procedure and readily available reagents.

A highly enantioselective palladium-catalyzed [3 + 2] cycloaddition of propargylic esters with β-ketoesters has been realized by employing a newly developed chiral ferrocene/benzimidazole-based P,N-ligand. This protocol features a good tolerance of functional groups in both propargylic esters and β-ketoesters, thereby delivering a variety of highly functionalized chiral 2,3-dihydrofurans bearing an exocyclic double bond at the 3-position in good yields and with high enantioselectivities (up to 98% ee).

A novel strategy to synthesize 1,3-enynes has been successfully developed based on Cu(I)-catalyzed cross-coupling of α-diazo phosphonates and alkynes with a subsequent Horner–Wadsworth–Emmons (HWE) type reaction. This method provides straightforward access to conjugated enynes with high efficiency, good stereoselectivity and excellent functional group compatibility. Copper(I) carbene migratory insertion plays a crucial role in this transformation.

This Review summarizes the advances in the construction of all-carbon quaternary stereocenters via catalytic enantioselective desymmetrization of prochiral and meso-compounds, highlights the power and potential of this strategy in the total synthesis of natural products and biologically active compounds, and outlines the synthetic opportunities still available.

The title ligand is applied in asymmetric 1,4-addition reactions of aryl boronic acids to α,β-unsaturated ketones to give chiral β-arylated ketones with high enantioselectivity.

The first nickel-catalyzed intermolecular hydroacylation reaction of alkenes with simple aldehydes has been developed. This reaction offers a new approach to the selective preparation of branched ketones in high yields (up to 99%) and branched selectivities (up to 99:1). Experimental data provide evidence for reversible formation of acyl–nickel–alkyl intermediate, and DFT calculations show that the aldehyde C–H bond transfer to a coordinated alkene without oxidative addition is involved. The origin of the reactivity and regioselectivity of this reaction was also investigated computationally, which are consistent with experimental observations.

The imidazo[2,1-b][1,3,4]thiadiazoles are converted to 2-(arylthio)-1H-imidazoles using aryl halides under Cu(acac)2-catalysis and microwave irradiation.

The high efficiency of this reaction relies on orthogonal activation of the AlCl(salen) complex and Tms—CN by the phosphorane and POPh3, respectively.

A new class of phenolic lactones with trivial names of spiromastilactones A-M (1-13) was isolated from a deep-sea derived Spiromastix sp. fungus. Their structures featured by various chlorination at aromatic rings were determined on the basis of extensive spectroscopic analyses. An antiviral assay revealed that most of the tested compounds exert inhibitory activity against WSN influenza virus with low cytotoxicity, while the structure-activity relationships were discussed. Spiromastilactone D (4), a 5'-chloro-2'-methoxy substituted analogue, displayed the most potent to inhibit a panel of influenza A and B viruses in addition to drug-resistant clinical isolates. Mechanistic investigation resulted in that compound 4 bonded to hemagglutinin protein (HA), potentially at the spherical head, and disrupted the HA-sialic acid receptor interaction, that is essential for the attachment and entry of all influenza viruses. In addition, compound 4 also showed inhibitory effect toward viral genome replication via targeting viral RNP complex. The synergistic effects of 4 on both viral entry and replication assumed it to be a promising lead for the development of a new influenza inhibitor.

This method provides access to Boc-protected β,γ-unsaturated α-amino acid esters with excellent yields and enantioselectivities.

Based on bioactive screening results, two new iridoid glycosides, named rotunduside G (1) and rotunduside H (2), were isolated from the rhizomes of Cyperus rotundus, together with four known ones, negundoside (3), nishindaside (4), isooleuropein (5) and neonuezhenide (6). Their structures were elucidated on the basis of spectroscopic methods and from literature values. In mice models of despair, 1 and 2 showed significant antidepressant activity.

We report here an unprecedented Fe/Cu synergistically catalyzed deesterificative or deamidative oxyphosphorylation of unsaturated carboxylates or amides with H-phosphonates. The valuable β-ketophosphonates were obtained along with chemoselective cleavage of Csp2–C(CO) or Csp–C(CO) bonds in good yields under oxygen atmosphere with a wide substrate scope.

We report the first example of the highly enantioselective synthesis of structurally diverse chiral dithioketals via asymmetric sulfenylation of various types of S-based nucleophiles, catalyzed by a cheap cinchona alkaloid derivative, dihydroquinine.

We report an efficient Mukaiyama-aldol reaction of tryptanthrin with fluorinated enol silyl ethers, which is carried out in methanol without the use of any catalyst. This method is applied to the total synthesis of the difluoro analogues of the natural product Phaitanthrin B.

Most of the products show in vitro inhibition activity against Staphylococcus aureus (MTCC96) comparable to Penicillin.

3-Substituted 3-aminooxindoles represent a type of privileged scaffold widely present in natural products and pharmaceutically active compounds. Thus, their efficient construction is of current interest. This account describes our efforts in the development of new strategies and reactions for facile access to this prominent framework. 1 Introduction 2 Nucleophilic Addition to Isatin Ketimines 3 Direct Amination of 3-Substituted Oxindoles 4 Substitution Reactions of 3-Hydroxyoxindoles 5 Conclusion and Outlook

Eight new cycloartane triterpenoids are isolated from the ethanol extract of the rhizomes of Beesia calthifolia along with six known compounds.

In this work, a facile and efficient method for the preparation of K2XF6:Mn4+ (X = Si, Ti and Ge) red phosphors is reported. They were synthesized by adding KF to precipitate a warm mixed solution with XO2, KMnO4 and HF as raw materials. After the doping of Mn4+, although the obtained products exhibit irregular micro-sized particulate morphologies, they present the same single phases as their matrices and no impurities can be found. The optical properties of the fluoride complexes were investigated using photo-luminescence spectroscopy, diffuse reflectance spectroscopy, and luminescence decay curves. The complexes presented bright red emission under blue light illumination, and warm white-light-emitting diodes with low correlated color temperature, high color rendering index and high luminous efficiency, with values of 3156 K, 84.9 and 138.4 lm W−1, respectively, were achieved by coating a mixture of the red phosphor with commercial Y3Al5O12:Ce3+ on blue-GaN chips.

A series of novel chiral phosphoramidite ligands based on chiral-bridged biphenyl backbones have been prepared conveniently and characterized. The ligands complexed with [IrCodCl]2 provided the first iridium catalyst system for the asymmetric addition of arylboronic acids to N-protected isatins with high efficiency. When performed in THF/H2O at 80 °C with 2 equiv of the arylboronic acids, the transformations acquired good to excellent results (up to 98% yield and 95% ee).

Fistulain A (I) displays anti-TMV (tobacco mosaic virus) activity, and both Fistulains show weak cytotoxicity.

The method leads to the desired difunctionalized synthons which are of high interest in synthetic organic and medicinal chemistry.

Aside the shown failed reactions, the following substrates also do not react: allylbenzene and 4-phenylbut-1-ene as well as 2-sulfanylfuran and -pyridine.

A synergistic Cu/Fe-catalyzed aerobic oxyphosphorylation of alkynes or alkynyl carboxylic acids with H-phosphonate is disclosed. The useful β-ketophosphonate products were obtained in good yields under oxygen atmosphere in a novel way. This reaction exhibits a wide substrate scope, and the mechanistic experiments indicate that a radical mechanism forms both C–P and C═O bonds simultaneously. This mechanism contrasts existing aerobic difunctionalization of alkynes.

The enantioselective conjugated addition of tritylthiol to in situ generated ortho-quinone methides in the presence of a squaramide organocatalyst is studied.

Di- and trisubstituted furans are synthesized from easily available substrates by a new one-pot tandem Wittig/conjugate reduction/Paal—Knorr reaction.

The title compounds (II) are obtained from N-(phenylsulfonyl)methacrylamides (I) via a one-pot radical cascade involving substitution-desulfonylation-cyclization steps in one pot using NaNO2 as nitro source and potassium peroxodisulfate as an oxidant.

The presented cycloisomerization proceeds through an anti-Markovnikov addition by using a base in catalytic amount.

A rare example of a one-pot process that involves asymmetric triple relay catalysis is reported. The key step is an asymmetric [1,5] electrocyclic reaction of functionalized ketimines. The substrates for this process were obtained in situ in a two-step process that involved the hydrogenation of nitroarenes with a Pd/C catalyst to yield aryl amines and their subsequent coupling with isatin derivatives in a Bronsted acid catalyzed ketimine formation reaction. The electrocyclization was catalyzed by a bifunctional chiral Bronsted base/hydrogen bond donor catalyst. The one-pot process gave the desired products in good yields and with excellent enantioselectivity.

The nitrobenzoic acid-mediated reaction of phenols, formaldehyde, and benzylimidazolidinones furnishes spirochroman derivatives in moderate to good yields and good to excellent diastereoselectivities.

A new cinchona alkaloid derived bifunctional tertiary amine-phosphoramide C1e is identified as a highly enantioselective catalyst for Michael addition of both unprotected 3-arylthio- and 3-alkylthiooxindoles to nitroolefins. The phosphoramide moiety of C1e plays an indispensable role in this reaction.

The reduction of the pentavalent phosphine in the products to a trivalent one is demonstrated for one product (XII).

Currently, there is a renewed interest in common dietaries and plant-based traditional medicines for the prevention and treatment of cancer. In the search for potential anticancer agents from natural sources, ursolic acid (UA), a pentacyclic triterpenoid widely found in various medicinal herbs and fruits, exhibits powerful biological effects including its attractive anticancer activity against various types of cancer cells. However, the limited solubility, rapid metabolism and poor bioavailability of UA restricted its further clinical applications. In the past decade, with substantial progress toward the development of new chemical entities for the treatment of cancer, numerous UA derivatives have been designed and prepared to overcome its disadvantages. Despite extensive effort, discovery of effective UA derivatives has so far met with only limited success. This review summarizes the current status of the structural diversity and evolution in medicinal chemistry of UA analogues and provides a detailed discussion of future direction for further research in the chemical modifications of UA.

The novel metal-free cascade reaction starts from aldehydes and methacrylamides and it enriches current methods of generating oxindole derivatives.

The catalytic asymmetric electrophilic amination has been established as a fruitful methodology for the construction of nitrogen-bearing tetrasubstituted carbon stereocenters, with its roots nourished by the latest achievements in chiral catalysis and synthetic strategies. This review summarizes the recent progresses, briefly discusses the reaction mechanism and challenges in this context, and outlines synthetic opportunities for future development. 1 Introduction 2 Transformations Based on Azodicarboxylates 2.1 α-Substituted Prochiral Aldehydes and Ketones 2.2 Ketenes 2.3 Doubly Activated Dicarbonyl Compounds 2.4 Heteroatom-Containing Activated Methines 2.5 Heterocyclic Nucleophiles 3 Amination Reactions Using other Amination Reagents 4 Conclusion

H8-BINOL-derived phosphine-oxazolines complexed with iridium were successfully applied for the asymmetric hydrogenation of the carbon-carbon double bond of exocyclic α,β-unsaturated carbonyl compounds. A valuable series of α-chiral cyclic ketones, lactones, and lactams were therefore provided via the reaction in high yields and good to excellent enantioselectivity of up to 95 % ee. The effects of the ligands and substrate structures on the asymmetric catalysis were also discussed.

This paper discloses the first example of photocatalytic direct decarboxylative hydroxylation of carboxylic acids. It enables the conversion of a variety of readily available carboxylic acids to alcohols in moderate to high yields. This unprecedented protocol is accomplished under extremely mild reaction conditions using molecular oxygen (O2) as a green oxidant and using visible light as a driving force.

The first highly enantioselective intramolecular N−H bond insertion was realized by using copper catalysts modified with chiral spirobisoxazoline ligands, which provides a novel strategy for the synthesis of chiral 2-carboxytetrahydroquinolines. This reaction features fast reaction rate, high yield, high enantioselectivity, and mild reaction conditions.

A novel copper-catalysed sulfenylation method by using the inorganic salt Na2S2O3 and alkyl halides (Cl, Br, I) or iodobenzene homologues is described. The reactions proceeded smoothly, giving regioselective 2-phenylimidazo[1,2-a]pyridine thioether derivatives in good yields via a C–H functionalization process. More importantly, this method has extended the existing methods by offering a better method which can make both alkyl and aryl thioether derivatives under one set of reaction conditions.

A facile and consecutive one-pot, multi-component reaction for synthesis of trifluoromethylated spirochromeno[2,3- c ]-6 H -pyrazol-2′,5-dione derivatives by the reaction of isatin, cyclohexane-1,3-dione and 1-aryl-3-(trifluoromethyl)-1 H -pyrazol-5(4 H )-one in the presence of p - toluenesulfonic acid ( p -TSA) with good yields was reported. Compared with the stepwise reactions, the p -TSA played dual roles as both catalyst and dehydrating agent in the conversion. The structures of new compounds were determined by spectroscopic methods and X-ray diffraction analysis. In addition, a possible mechanism for the formation of compound 5 was presented.

Broensted acid Tf2NH catalyzes Friedel—Crafts type head-to-tail hydroalkenylation and hydroarylation of vinylarenes [(I), (III), (V), and (VII)] under mild reaction conditions providing a readily scalable, metal-free, and practical access to bioactive trans-1,3-diaryl-1-butenes [(II), (IV), and (IX)] and cyclic analogues [(VI) and (VIII)] and 1,1-diarylalkanes (XI), resp., in high regioselectivity.

α-Amino phosphinates with P , C -stereogenic centers were prepared from a P -retained addition of ( R P )-(−)-menthyl H -phenylphosphinate to ( R )-aldimines with up to 86:14 dr under catalyst and solvent free condition at ambient temperature; the single ( S P , S α-C )-stereoisomers were isolated in moderate yields. Chirality on the nitrogen of chiral aldimine was proposed to control the stereoselectivity, and the (−)-menthoxyl showed mismatched asymmetric induction with ( S )-aldimines.