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We report an approach to synthesize molecular tungsten-oxide-based pentagonal building blocks, in a new {W21 O72} unit, and show how this leads to a family of gigantic molecular architectures including [H12W48O164](28-) {W48}, [H20W56O190](24-) {W56}, and [H12W92O311](58-) {W92}. The {W48} and {W56} clusters are both dimeric species incorporating two {W21} units and the {W56} species is the first example of a molecular metal oxide cluster containing a chiral "double-stranded" motif which is stable in solution as confirmed by mass spectrometry. The {W92} anion having four {W21} units is one of the largest transition metal substituted isopolyoxotungstates known.

A simple method for the synthesis of the title compounds (III) using inexpensive and readily available 2-iodoanilines (I), various aromatic aldehydes (II) and selenium powder without ligands and other additives under mild reaction conditions is presented.

Combination of a cinchona alkaloid-derived primary amine with L-leucine gives a dual amine system with promising catalytic activity in enantioselective fluorination reactions of indanone-2-carboxylates (I).

(TEAH)5Na [H5W18O59(IO3)] ·5H2O (I; TEAH: (HO-CH2-CH2)3NH+), the first example of a polyoxometalate with encapsulated IO3-, is synthesized from an aqueous solution of Na2WO4, H5IO6, and TEAHCl (pH 1.3 adjusted with 6M HCl, reflux, 1 h; yield given in g).

Dawson-like clusters {W18O56XO6} (X: I, Te) with localized redox active inner-cluster templates are characterized by cyclic voltammetry, UV and EPR spectroscopy, and DFT calculations.

K10Li14 [W36Si4O136Mn10(OH)4 (H2O)8] ·60H2O (I) and the isomeric cluster K10Li13.5Mn0.25 [W36Si4O136Mn10(OH)4 (H2O)8]·60H2O (II), which differs only in the positions of the Mn centers captured in the precursor fragments, are synthesized by reaction of K8[γ-SiW10O36] with MnCl2 in an aqueous LiCl solution under ambient conditions (pH 8.3, 13% yield).

By using a new type of lacunary tungstoselenite {Se2W29O103} (1), which contains a “defect” pentagonal {W(W)4} unit, we explored the assembly of clusters using this building block and demonstrate how this unit can give rise to gigantic nanomolecular species, using both a “one-pot” and “stepwise” synthetic assembly approach. Specifically, exploration of the one-pot synthetic parameter space lead to the discovery of {Co2.5(W3.5O14)(SeW9O33)(Se2W30O107)} (2), {CoWO(H2O)3(Se2W26O85)(Se3W30O107)2} (3), and {Ni2W2O2Cl(H2O)3(Se2W29O103) (Se3W30O107)2} (4), effectively demonstrating the potential of the {Se2W29} based building blocks, which was further extended by the isolation of a range of 3d transition metal doped tetramer family derivatives: {M2WnOm(H2O)m(Se2W29O102)4} (M = Mn, Co, Ni or Zn, n = 2, m = 4; M = Cu, n = 3, m = 5) (5 - 9). To contrast the ‘one-pot’ approach, an optimized stepwise self-assembly investigation utilizing 1 as a precursor was performed showing that the high nuclearity clusters can con...

{(Me2NH2)6 [H4CoW11O39] ·6H2O}n (I), Na4(Me2NH2)10 [H4CoW22O76(H2O)2] ·20H2O (II), and Na16(Me2NH2)72 [H16Co8W200O660 (H2O)40]·ca.600H2O (III) are synthesized in a networked reactor system (three primary reactors, each with two external reagent inputs, are connected together in a triangular arrangement with a central secondary reactor) from aqueous solutions of Na2WO4, CoCl2, Me2NH·HCl, Na2S2O4, and HCl.

A very simple, direct, bismuth-catalyzed conjugate reduction protocol that allows for the catalytic regioselective formation of substituted ketones from enones under mild conditions has been developed. We have shown for the first time that the combined poly(methylhydro)siloxane-malononitrile system can serve as an efficient reductant/reagent in 1,4-conjugate reduction of enones. The regioselectivity, efficiencies, and experimental simplicity of the present method complements the more complex methods previously employed in copper or palladium-catalyzed reduction. This method should prove attractive because of its mild reaction conditions and the interesting chemistry of combining the use of poly(methylhydro)siloxane and malononitrile for selective reduction.

A new family of TeIV-containing heteropolyoxometalate building blocks which consist of a {W3} top unit and one, two, and three layers of {TeW6} base units in [TeW9O33]8-, [Te2W15O54]10-, and [Te3W21O75]12-, respectively, is synthesized.

The reaction of anilines with chalcones is best catalyzed by cinchonine in combination with TmsI or TmsCl.

A series of spirooxindoles (II) is readily prepared by an intramolecular oxidative coupling reaction of benzamides (I).

Shionane-type triterpenes (I) and (II) are isolated from the title herb which is used in traditional Chinese medicine for the treatment of cough.

The reaction of anilines in the presence of the activator Bu4NBr results in formation of brominated products.

Anilines (I) react with phenyliodonium ylides (II) in the presence of a catalytic amount of a Lewis acid to provide the C—N coupling products (III), which are precursors for the construction of indoles.

K44Na10 [H34W119Se8Fe2O420] ·220 H2O is synthesized by slow evaporation of an aqueous solution of Na2WO4, Na2SeO3, KCl, and Fe(NO3)3 (AcOH, HCl, pH 1.7; 4% yield).

Acenaphthenone (ANO) is an effective electron donor and undergoes stepwise photooxygenation sensitized by 9,10-dicyanoanthracene, affording hydroxylactone and anhydride derivatives; the electron transfer mechanism via an enol intermediacy was verified by the enhancement effect of biphenyl, fluorescence quenching, exciplex emission and chemically induced dynamic nuclear polarization (CIDNP).

Gigantic heteropolyoxotungstates are synthesized using the SeO32- group as both heterotemplate and linker.

The Dawson-like polyoxometalate clusters (TEAH)6[H2W18O57(SO3)] (1) and (DMAH)8[W18O56(SO3)2(H2O)2] (2) were synthesized under similar reaction conditions by employing triethanolammonium (TEAH+) and dimethylammonium (DMAH+) as cations, respectively. Crystallographic studies revealed that compound 1 has a compressed, peanut-like {W18} cage containing a single sufilte anion where each cage metal atom supports one terminal oxo-based ligand whereas compound 2 also has a {W18} cage, but four of the eighteen cage metal atoms support two terminal oxo-based ligands with two sulfite anions embedded in the cluster.

The boron trifluoride etherate (BF 3 ·Et 2 O)-catalyzed reactions between phenyliodonium ylides and enamine esters provide an efficient method for the synthesis of polysubstituted pyrroles.

Selective cleavage of both active and inert C–C bonds in substituted allylcyclopropanes was realized via a novel ligand-controlled approach using zirconocene(II)-1-butene or zirconocene(II)-benzyne complexes.

The cryo game: Heteroatom-embedded nanofunctional clusters are described that incorporate a [Te(VI)O(6)](6-) species contained within a {W(18)O(54)} cage. Not only does the tellurium-based species activate the {W(18)O(54)} cluster surface for assembly of larger nanoscale structures, such as [H(10)Te(VI) (2)W(58)O(198)](26-), it also undergoes a redox transformation inside the cluster from [Te(VI)O(6)](6-) to [Te(IV)O(3)](2-).

Highly efficient Michael addition reactions of malonates to nitroalkenes catalyzed by novel chiral thioureas derived from optically pure BINOL and amino acids are reported. Various trans-nitroalkenes reacted with malonates affording the desired products in up to 95% yield with excellent enantioselectivities (up to 97% ee).

The PtCl2-catalyzed reactions between indoles and ethyl propiolate gave rise to mono and double addition products. The composition of the products was largely influenced by the substituents on the indoles as well as the amount of ethyl propiolate used. o-Alkynylanilines reacted with ethyl propiolate and dimethyl acetylenedicarboxylate under the catalysis of PtCl2 to generate the corresponding 2,3-di-substituted indoles. The reaction proceeded by following a sequential cyclization/intermolecular addition pathway. (C) 2008 Elsevier Ltd. All rights reserved.

Finding the missing species: Two isopolyoxotungstate clusters with unprecedented “S”-shaped [H4W22O74]12− and “§”-shaped [H10W34O116]18− geometries are presented. The development of this structural complexity comes from the structural evolution based on the {W11} fragment and establishes a new building block principle in isopolyoxotungstate chemistry. The evolved clusters can only be isolated in the presence of sulfite ions.

4-Substituted 1,2-oxaborol-2(5H)-ols were prepared through copper-catalyzed carbomagnesation of propargyl alcohol, followed by the transmetallation of magnesium to boron in a one-pot procedure. The Suzuki-Miyaura cross-coupling of these new 2,2-disubstituted alkenylboronic acids with aryl halides afforded stereodefined 2,3-disubstituted allyl alcohols in good to excellent yields.

A new boronic acid protecting group, 1-(4-methoxyphenyl)-2-methylpropane-1,2-diol (MPMP-diol), has been developed. Both protection and deprotection can be accomplished under mild conditions with quantitative conversions. The deprotection can be carried out using 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ).

Glycans in the form of glycoproteins or glycolipids play very critical roles in various biological and pathological processes including inflammation, cancer metastasis, immune reactions, embryo development, cell–cell communications and adhesions, blood generation, etc. Proteins (lectins) that can recognize carbohydrates have played very important roles in studying glycobiology. Small molecule mimics of lectins will be very useful in the development of new therapeutics and diagnostics. Along this line, boronic acids have been widely used in the design and synthesis of small organic compounds that mimic the function of lectins. This review examines in detail the factors that are important for the design of boronic acid-based lectin mimics, boronolectins. © 2005 Wiley Periodicals, Inc.

Boronic acids are important intermediates and molecular recognition moieties in a wide variety of applications. In our research, we have found that the synthesis of ortho-substituted arylboronic acids is problematic with the commonly used bis(pinacolato)diboron in palladium-mediated borylation reactions. As a substitute, we have found that bis(neopentyl glycolato)diboron is a much more efficient borylation agent for the synthesis of sterically hindered ortho-substituted arylboronic acids.

Presented is a methodology to oxidatively cleave α-hydroxyketones and α- or β-diones using the environmentally benign reagent KHSO5, prepared easily from Oxone, to diesters in one simple transformation. In addition, we undertook a mechanistic study to provide a plausible mechanistic interpretation. These reactions may prove to be valuable alternatives to other related metal-mediated processes.

[reaction: see text] Stereospecific cyclopropanation of alkenylboronic esters of pinacol followed by in situ treatment with excess KHF(2) afforded the corresponding potassium cyclopropyl trifluoroborates in high yields, which then underwent Suzuki-Miyaura cross-coupling reactions with aryl bromides to give cyclopropyl-substituted arenes in good yields with retention of configuration. This promises to be a useful method for the synthesis of enantiomerically pure cyclopropanes.

An antimicrobial cerebroside, pinelloside, was isolated from the air-dried tubers of Pinellia ternata (Thunb.) Breit. Its structure was determined as 1-O-beta-D-glucopyranosyl-(2S,3R,4E,11E)-2-(2'R-hydroxyhexadecenoylamino)-4,11-octadecadiene-1,3-diol by chemical transformation and extensive spectroscopic analyses (IR, MS, 1H and 13C NMR, DEPT as well as 2D NMR techniques HMBC, HMQC, 1H-1H COSY and NOESY). The antimicrobial assay showed that this compound was inhibitory to the growth of Bacillus subtilis, Staphylococcus aureus, Aspergillus niger and Candida albicans, with minimum inhibitory concentrations (MICs) of 20, 50, 30 and 10 microg/ml, respectively. The MICs of penicillin G against bacteria B. subtilis, S. aureus, E. coli, P. fluorescens and H. pylori were 0.80, 0.34, 0.56, 1.34 and 0.92, and those of ketoconazole against fungi A. niger, C. albicans and T. rubrum 0.90, 0.65 and 1.0 microg/ml, respectively.

In the presence of 1 equiv. of CuCl, the reaction of zirconacyclopentenes with 2 equiv. of aldehydes from −78°C to room temperature afforded tetrahydrofuran derivatives in good isolated yields upon hydrolysis with aqueous 3N HCl; oxazirconacycloheptenes, generated in situ from zirconacyclopentenes with one aldehyde, was found to be the reactive intermediate.

Bioassay-guided fractionation of the ethanol extract of the roots and rhizomes of Veratrum taliense yielded two new and thirteen known steroidal alkaloids. The structures of the two new compounds, neoverataline A and B, were established by extensive spectroscopic analyses to be 3,4-secocevane-4,9-olid-14,15,16,20-tetra-ol-3-oic acid and 3,4-secocevane-4,9-olid-7,14,15,16,20-penta-ol-3-oic acid, respectively, and are a novel carbon skelton. All of the fifteen alkaloids were subjected to in vitro antifungal assays, which showed that the verazine- (veramitaline, stenophylline B, stenophylline B-3-O-β- d -glucopyranoside, veramiline-3-O-β- d -glucopyranoside) and jerveratrum-type (jervine, jervine-3-O-β- d -glucopyranoside) alkaloids exhibited strong antifungal activities against the phytopathogenic fungus Phytophthora capisis with MICs of 160, 120, 160, 80, 80 and 120 μg·L−1, respectively. Furthermore, the verazine-type alkaloids stenophylline B, stenophylline B 3-O-β- d -glucopyranoside and veramiline 3-O-β- d -glucopyranoside were shown to also inhibit the growth of another fungal phytopathogen Rhizoctonia cerealis with MICs of 160, 120 and 120 μg mL−1. The MICs of triadimefon (an antifungal agrochemical used herein as a positive control) against P. capisis and R. cerealis were 120 and 80 μg mL−1, respectively. A preliminary structure–activity relationship regarding these alkaloids has been formulated.

Leptosphaerone (1), a metabolite with a new C skeleton, was isolated from the AcOEt extract of the culture of Leptosphaeria sp., an endophytic fungus (strain number: IV403) found in Artemisia annua. The structure of 1 was elucidated on the basis of spectral analyses, including homo- and hetero-nuclear correlation NMR experiments (HMQC and HMBC), with its absolute configuration determined by CD and NOED studies.