Volume 9 Issue 4, April 2017

A unique transformation for the site-selective cleavage of one C–C single bond and two C–H bonds in sequence has now been developed. This enables a simple carbon skeleton to be reorganized into a significantly more complex form with remarkable efficiency.

Biomimetic molecules that can be easily tailored offer numerous opportunities. Now, boron-based clusters have been shown to be excellent biomimetics. The ease with which the cluster surfaces can be modified stands to change how chemists might go about preparing materials for imaging, drug delivery and other applications.

Although ribose aminooxazoline has been shown to be a potential intermediate in prebiotic pyrimidine ribonucleotide synthesis, a route by which this could occur has remained elusive. Now, a remarkably efficient photoanomerization reaction has been investigated by theory and experiment. The new route affords enantiomerically pure ribonucleotides when the starting material is enantioenriched.

Chemical reconstitution of the triose glycolysis pathway is controlled by α-phosphorylation and provides a generational link between prebiotic ribonucleotide synthesis, triose glycolysis and serine metabolism. Now, research suggests that unification of nucleotide synthesis and triose metabolism may have been a fundamentally important step towards the origins of life.

An unanswered question in the RNA world scenario is how sequence information could be transferred during replication of duplex RNA. Without the aid of sophisticated enzymes, strand reannealing occurs more quickly than template-directed synthesis. Now, a plausible prebiotic solution to this problem is presented, in which a viscous solvent enables information transfer from a gene-length double-stranded template.

Lysine-rich peptides from the ribosomal core and derived homolysine decapeptides of either L-, D- or mixed chirality have now been shown to enhance RNA polymerase ribozyme activity at low magnesium concentrations, accelerate ribozyme evolution and enable templated RNA synthesis within membranous protocells.

The operational simplicity of modifying the surfaces of thiol-capped gold nanoparticles has been a hallmark of their success in materials chemistry, despite having limited control over the surface composition. Now, S_NAr chemistry on activated perfluoroaromatics has been shown to mimic this simplicity and allow for the synthesis of atomically precise nanomolecules.

Singlet fission — the splitting of a singlet exciton into two triplets — is a process that could be exploited to improve the power conversion efficiency of solar cells. Spectroscopic data now suggest that coherent and incoherent mechanisms for singlet fission in crystalline hexacene coexist and occur on different timescales.

Aggregation usually prevents dissolution of graphene in water. Now, hydroxide ion adsorption has been shown to allow the stabilization of true single-layer graphene in water — with no surfactant required — so long as the liquid is degassed beforehand. The resulting aqueous dispersions can contain high concentrations of exfoliated graphene that are stable for several months.

A computational method to design cyclic protein homo-oligomers has been developed. Using this approach, a series of idealized repeat proteins incorporating designed interfaces that direct their assembly into complexes possessing cyclic symmetry were fabricated. 15 out of 96 oligomers that were characterized experimentally were shown to be consistent with the computational model.

Existing methods for C–H activation depend on pre-installed directing groups, the removal of which poses a practical limitation on the use of these reactions in synthesis. Now, a remote-selective C−H alkylation reaction of arenes using an in situ generated spiropalladacycle has been shown to furnish benzofurans and indoles without the need for a directing group.

Homogeneous crystal nucleation has now been observed by transmission electron microscopy in real time on a molecular scale. Countercation-dependent observations of polyoxometalate proto-crystal formation confirm existence of a higher energy classical molecular attachment mechanism, as well as a lower energy two-step mechanism via an intermediate dense phase.

Methods utilizing renewable feedstocks are critical to accessing molecules of industrial importance in light of the present ecological and economic climate. Here, it is shown that umpolung reactivity of carbonyl compounds can be used for nucleophilic additions to yield a diverse array of valuable alcohols as an alternative to using stoichiometric organometallic reagents.

Nature has evolved a variety of different mechanisms to generate chemical diversity; however, the reactions responsible for generating such diverse chemical libraries are often not clear. Now, the mechanisms employed by entomopathogenic bacteria for the biosynthesis of a large family of bioactive peptides have been identified. These include substrate promiscuity, enzyme cross-talk and enzyme stoichiometry.

Polytheonamides are giant peptide toxins produced by the uncultivated sponge bacterium Entotheonella factor. The biosynthesis of polytheonamides involves up to 50 post-translational modifications. Now, heterologous expression in Escherichia coli and Rhizobium hosts have shown that a minimalistic, iterative enzyme set introduces this exceptional molecular complexity via epimerizations, C-/N-methylations, hydroxylations, dehydration and proteolytic maturation.

The use of earth-abundant metals in catalysis is a prerequisite for the development of sustainable synthetic chemical processes for the future. Now, biomass-derived chemicals can be used in an efficient iron-catalysed reaction to make complex spirocycles. The resulting products contain two asymmetric centres that are furnished in high stereoselectivity.

Alasdair Skelton and Brett F. Thornton examine the twisting path through the several discoveries of ytterbium, from the eighteenth century to the present.