Volume 6 Issue 2, February 2014

High selectivity is essential in the enzymatic biosynthesis of complex natural products. Now, the discovery of multiple sequential bifurcations on the reaction path towards the formation of a diterpenoid shows how dynamics affect selectivity, and suggests how enzymes may steer reactions towards a specific product.

Cytochrome P450 enzymes are able to oxidize substrates that are more inert than their own surrounding protein framework. Now, a quantitative understanding has emerged as to how the enzymes accomplish this remarkable feat.

The organic synthesis of graphene nanostructures requires exceptionally efficient chemistry and is made more challenging by difficulties in characterization and processing. Now, solution-dispersible graphene nanoribbons have been synthesized on the gram scale.

Discovering and validating new targets is urgently required to tackle the rise in resistance to antimalarial drugs. Now, inhibition of the enzyme N-myristoyltransferase has been shown to prevent the formation of a critical subcellular organelle in the parasite that causes malaria, leading to death of the parasite.

Metal-coordinating groups are widely used to direct C–H functionalization. Now the combination of an alkene hydrosilylation, C–H activation and C–Si oxidation has been used to achieve a formal 1,4-dioxygenation of alkenes.

Mechanically robust and shape-persistent hollow toroidal polymer microrings have been synthesized directly by thiol-ene photopolymerization of rectangular-shaped monomers with dithiols. The size of the microrings can be tuned by varying the monomer concentration. The resulting structures can encapsulate molecules in their hollow interiors and also serve as scaffolds to template the formation of circular arrays of metal nanoparticles.

A terpene-forming carbocation reaction is described for which a single transition-state structure leads to the formation of many isomeric products via pathways that feature multiple sequential bifurcations. Dynamic effects are shown to contribute to the selectivity of the reaction, with consequences for how enzymes control the biosynthesis of complex natural products.

Chemical validation of new drug targets is urgently required to help develop new antimalarial therapies. Here, chemical proteomic tools and selective enzyme inhibitors are combined to study protein lipidation in human malaria parasites, leading to in vitro and in vivo validation of the enzyme N-myristoyltransferase as a drug target.

Selective C–H functionalization reactions often rely on the directing effects of chelating groups embedded within the substrate. Here, an alkene hydrosilylation is used to install a pyridine-containing auxiliary that subsequently directs C–H functionalization at the homoallylic position. Oxidation of the silacycle product results in a formal 1,4-dioxygenation of an alkene.

Liquid-phase-processable graphene nanoribbons (GNRs) over 200 nm long and with well-defined structures have now been synthesized by a bottom-up method, and are found to have a large optical bandgap of 1.88 eV. Scanning probe microscopy revealed highly ordered self-assembled monolayers of the GNRs, and the high intrinsic charge-carrier mobility of individual ribbons was characterized by terahertz spectroscopy.

It has been suggested that bioactive natural products are an attractive starting point for the construction of screening libraries. Here, four families of biologically active alkaloids are used as the basis for the construction of 686 new compounds suitable for screening. The libraries thus prepared have characteristics comparable to representative natural products and are highly rule-of-five compliant.

The reaction F + H₂ → HF + H is the only source of interstellar HF, but studying it at relevant cold temperatures has proved problematic. Now, the rates of this reaction have been measured at various temperatures down to 11 K and their remarkable agreement with state-of-the-art quantum mechanical calculations has been shown. (Background © Image Asset Management/Alamy)

Despite advances in C–H activation reactions in the past decade, the development of suitable ligands that enable catalytic C(sp³)–H bond functionalization remains a significant challenge. Here, the discovery of a mono-N-protected amino acid ligand enables Pd(II)-catalysed cross-coupling of C(sp³)–H bonds in triflyl-protected amines with arylboron reagents.

Graphene oxide sheets hold promise for a variety of applications but are disordered and inhomogeneous on synthesis. Although processes to resolve this exist they typically remove oxygen groups, affecting the sheets’ properties. Now, a scalable, mild thermal annealing procedure has been devised that enhances the optical and electronic properties of graphene oxide sheets through phase transformation, while preserving their oxygen functionality.

Mechanistic studies of reductive elimination that forms aryl–aryl bonds from simple mono- and dinuclear gold phosphine complexes are disclosed. The observed rates for reductive elimination are unusually fast, even at temperatures as low as –52 °C, providing insight into the fundamental reactivity of oxidized organogold complexes.

Elements that are widespread in nature and have been used for thousands of years are not typically deemed exciting, but Anders Lennartson argues that we shouldn't take zinc for granted.