Revamped for the 21st century: The original Stille protocols for cross-couplings are difficult to recognize in the newer nickel-catalyzed reactions of monoorganotin compounds with secondary alkyl halides (see scheme). This new coupling scheme avoids the formation of toxic byproducts.

Cationic polycyclization cascades: The stereoselective transformations of linear polyolefins to give cyclic triterpenes (see scheme) have fueled half a century of intense research. Structures of triterpene cyclases complexed with the substrate analogue 2-azasqualene and the reaction product lanosterol provide new insights into the elegant mechanisms of these enyzmes.

Among the numerous synthetic methods for the preparation of chiral products with high enantiomeric excess, kinetic resolution is the oldest. It is unique, as it has been applied to practically every type of chiral substrate, and can be combined with any method of enantioselective synthesis. The scheme shows an example of dynamic kinetic resolution through the enantioselective catalytic hydration of an equilibrated racemic β-ketoester.

A network of platinum nanotubes with diameters of about 15 nm and walls 1 nm thick that interconnect to form an open, doubly bicontinuous structure (see high-resolution electron micrograph) is formed by coating platinum on a nanoporous gold template then dissolving away the mold. The structure is stable at 125 °C for at least 24 hours, but starts to deform at 150 °C and eventually forms nanoparticles.

Z for zinc and Z-DNA: As a result of different binding modes, a cationic zinc porphyrin discriminates between B and Z conformations of DNA and holds promise as a probe for Z-DNA. A very intense induced circular dichroism (ICD) effect with a bisignate spectrum is observed upon interaction of the porphyrin with Z-DNA (see graphic; porphyrin red, Z-DNA green), whereas only a weak ICD spectrum results upon its interaction with B-DNA.

Trapping the light fantastic-ally! Enhanced photocurrents are observed for hydrogen-bonded gold nanoparticle/CdS nanoparticle arrays associated with a gold electrode surface (see scheme) as a result of charge separation and controlled electron transfer at the electrode interface.

A one-component acceptor-donor-acceptor compound based on a rigid TCNQ-σ-TTF-σ-TCNQ system (see picture) exhibits a unique case of both intramolecular charge and electron transfer through space that is strongly dependent on the polarity of the medium. The strong dependence of the ground-state electronic structure on the solvent polarity provides an unprecedented case of solvatochromism.

No added salt: Transmission electron microscopy and small-angle X-ray scattering studies have shown that uni- and multilamellar vesicles with radii of 25.5 and 366 nm (see schematic diagram; the hydrophilic cation/anion groups are shown as green spheres and the hydrocarbon chains in blue), respectively, are formed from trimethyltetradecylammonium hydroxide and oleic acid in water. The multilamellar phase consists of seven bilayers.

Carefully selected combinations of directional forces can be used to rationally engineer crystals with particular anisotropic features. This approach has led to the generation of cleavable molecular crystals with parallel 15-Å channels by dipole-directed stacking of hydrogen-bonded sheets (see crystal structure). The network remains undeformed when guests included in the channels are exchanged.

Under wraps: A linear nickel filament is “wrapped” inside an eighteen-atom germanium enclosure made of two nine-atom deltahedral clusters (see structure; green Ge, yellow Ni).

A NADH turnover rate of 741 min⁻¹ in the oxidition of ethane to ethanol is observed with an engineered form of the heme monooxygenase cytochrome P450_cam—the first example of such activity for a P450 enzyme (GC analysis shown). Ethanol is formed at 78 min⁻¹ (10.5 % coupling). The mutant is ≈45 % high-spin in the absence of substrate, making it a useful platform for P450 structure–function studies.

High enantioselectivities (up to 94 % ee) were attained in the Michael addition of a variety of α,β-unsaturated imides 1 and malononitrile (2) catalyzed by bifunctional thiourea 4. The pyrrolidinone moiety of 1 plays a key role in the reaction. The reaction provides access to a variety of Michael adducts 3 (see scheme; R=aryl and alkyl groups).

A cycloaddition comes of age: The focal points of a stereoselective total synthesis of erythronolide A (see structure) are two Mg^II-mediated cycloadditions of nitrile oxides. Of broader significance, the strategy not only facilitates the synthesis of specific polyketide targets (i.e. natural products) but also opens up new possibilities for the preparation of non-natural analogues.

A cyclophane with allene and acetylene bridges has been prepared as a single enantiomer. This acetylenic allenophane (see structure) was synthesized by a series of palladium- and copper-mediated coupling reactions. The allene bridge was derived from the ring opening of a chiral epoxy alkyne, which was prepared by a Sharpless asymmetric epoxidation of an allylic alcohol.

The base-free anti-Markovnikov addition of secondary amides, anilides, lactams, ureas, bislactams, and carbamates to terminal alkynes is accomplished, for the first time, by a ruthenium-catalyzed reaction. Two complementary protocols provide stereoselective synthetic entries to either the E or the Z isomers (see scheme; cod=cycloocta-1,5-diene; DMAP=4-(N,N-dimethylamino)pyridine).

A thousand turnovers in bi- and triaryl formation: Substituted anilides have been ortho-arylated by aryl iodides under palladium catalysis (see scheme). This method is highly tolerant of the presence of additional functional groups (FGs). Even an iodo functionality on the anilide moiety and a bromo functionality on the aryl iodide are compatible with this methodology.

Protein binders: Three representative polyoxometalate (POM) compounds, for example 1, which is of the Wells–Dawson class, were found to interact with the basic fibroblast growth factor (bFGF, right). The binding induces dramatic conformational changes in the growth factor. POMs are promising leads for compounds that may represent a new avenue for the development of therapeutic agents against bFGF-induced angiogenesis.

Within the framework: The fused benzodipyrrole unit within the sapphyrin 1 has a significant influence on its structure as compared to those of usual sapphyrins. The fused benzene ring partly inhibits distortion of the macrocycle about the dipyrrole unit (see structure of 1⋅2 H⁺ 2 (p-CH₃C₆H₄SO₃⁻); C gray, N blue, O red, S yellow) and contributes to the significant red-shift of Q-bands.

A flat radical: Oxygen-bridged triphenylamine 1 and its radical cation 2 were prepared. The neutral compound has a shallow bowl structure, whereas the radical cation is planar. The properties of the highly stable radical cation were clarified; such compounds have potential applicability in electronic and magnetic materials.

Specific targeting of tumors with radioactive isotopes is the key for high-sensitivity scintigraphy detection. A labeled neutral endopeptidase (NEP) inhibitor is described that accumulates in vivo in tumor cells expressing this enzyme, which makes it a potential tool for noninvasive evaluation of NEP expression. Its structure (black with the label depicted in red, DTPA=diethylenetriaminepentaacetic acid) is shown in a model of the NEP active site (blue).

Designer drug: A polymer therapeutic was designed for a combination therapy of breast cancer. N-(2-Hydroxypropyl)methacrylamide was used as the model polymer platform to prepare a unimolecular polymer conjugate (see picture, radius of gyration: 12.8 nm) that combines an endocrine (the aromatase inhibitor aminoglutethimide, blue) and a chemotherapeutic agent (the anthraxcycline antibiotic doxorubicin, red).

Ceria nanoparticles as a support stabilize positive gold species and provide oxygen vacancies. The resulting solid exhibits an exceedingly high efficiency for the solventless aerobic oxidation of primary and secondary alcohols to carbonyl compounds (see picture).

In the loop: A reversible spin transition was observed by Raman spectroscopy on application of a single laser pulse (8 ns) in the hysteresis loop of the spin-crossover complex [Fe(pyrazine){Pt(CN)₄}]. This bi-directional, photoinduced spin switching occurs at room temperature over a wide region of bistability and involves magnetization as well as color changes (see picture).

Hopping holes: Oligopeptides with a photosensitive charge-injection system were synthesized and irradiated by a nanosecond laser. A multistep electron-transport process occurred which uses aromatic side chains as hole carriers (see scheme). The rates of this process indicate through-space electron transfer (a hopping mechanism).

The C₃ equivalent dihydroxyacetone was used in its protected form in proline-catalyzed Mannich reactions (see scheme). As little as 5 mol % catalyst is required when using 2,2,2-trifluoroethanol as solvent. The reaction is improved further (reaction time 10 min) under microwave conditions. PMP=p-methoxyphenyl.

Short and sweet: Starting from the commercially available precursors 1–3, selectively protected amino sugars and derivatives are obtained in one step and with high diastereo- and enantiomeric purity by means of a proline-catalyzed three-component Mannich reaction (see scheme, PMP=para-methoxyphenyl). This efficient organocatalytic procedure can be carried out smoothly on a multigram scale.

The at-line detection of an amino group oxidation catalyzed by the N-oxygenase AurF provides the first direct evidence for a stepwise enzymatic oxidation of aromatic amines to nitro groups via a hydroxylamine intermediate (see scheme). The sequential nature of this reaction is further supported by biotransformation of the intermediate and the identification of a p-aminobenzoate-derived azoxy side product.

Precipitation of charged amino acids in the presence of oppositely charged polyelectrolytes leads to liquid droplets of the corresponding polymer/amino acid complexes in water. The resulting emulsions are stable against crystallization and Ostwald ripening for several months but can also be used as a starting situation for crystallization of spherical, porous crystal superstructures (see SEM image of L-lysine).

Cyclic or acyclic: Not only modified cyclodextrins but also modified linear dextrins like the silylated (R)and acetylated (R¹) maltoheptaose derivatives 1 are suitable selectors for separating racemic N-trifluoroacetyl-O-alkyl esters of α-amino acids by gas chromatography. In the example shown, racemic N-trifluoroacetylserine O-ethyl ester is resolved.

Nothing sticks to Teflon? Going one better than “soap on a rope”, a recyclable fluorous rhodium hydrosilylation catalyst is described that is released from Teflon tape into dibutyl ether upon warming, and readsorbed upon cooling (see scheme).