Volume 9 Issue 6, June 2017

Using chiral modifiers on the surfaces of heterogeneous catalysts is a potentially fruitful route to practical stereoselective chemistry. Now, a study of the dynamics of prochiral adsorbates on modified surfaces has shown that they can rapidly interconvert between adsorption states of different prochirality.

Natural products often serve as sources of new drugs, either directly or after synthetic modification, but site-selective functionalization of complex small molecules is challenging. Now, a method has been developed that enables selective modification of a wide range of natural products by engaging a benzyne intermediate in a variety of reaction modes.

Femtochemistry, the real-time study of reactions on a timescale that captures the molecular and atomic activity involved, has traditionally been performed in the gas or liquid phase. It has now been extended to the solid state in a study that highlights how a controlled reaction environment can place steric constraints on the motions of photoproducts.

A programmable model of membraneless organelles comprised of intrinsically disordered proteins (IDPs) containing sequences of low complexity has now been developed. The rules governing the assembly of archetypal IDPs into biologically inspired mixed, layered and size-controlled configurations provides a new means for understanding intracellular phase behaviour of IDPs.

Dissociative reactions in the solid state are prone to sample damage. Now, improved sample handling and measurement conditions enable the study of the dissociative reaction of a model triatomic system in the solid state on ultrafast timescales, revealing the significant impact of lattice coordination on the reaction pathway.

The development of methods for the site-selective modification of natural products is a topic of contemporary investigation and importance. Now, it has been shown that benzynes produced by the hexadehydro-Diels–­Alder (HDDA) reaction react with many secondary metabolites, with a substantial preference for one of several potential pathways.

A chiral molecule on a metal surface can set up a prochiral molecule for an enantioselective reaction step by forming a hydrogen-bonded complex that imposes a specific adsorption geometry. Time-lapsed scanning tunnelling microscopy and density functional theory studies reveal that such complexes can sometimes switch between states of opposing prochirality.

A cytocompatible controlled radical polymerization method has now been developed that initiates polymer synthesis directly on the surface of living cells. This method achieves significantly enhanced polymer grafting and enables active manipulation of cellular phenotypes.

The first example of an asymmetric silver-catalysed intermolecular bromotrifluoromethoxylation of alkenes has been described with trifluoromethyl aryl sulfonate as a new trifluoromethoxylation reagent. This reaction is operationally simple, scalable and proceeds under mild reaction conditions, which can be applied to the late-stage trifluoromethoxylation of complex small molecules.

Mono-iron hydrogenase promotes the heterolytic cleavage of H₂ and subsequent hydride transfer to its organic substrate, H₄MPT⁺, which serves as a CO₂ ‘carrier’ in methanogenic pathways. Now, using an anthracene-scaffold-based approach, a synthetic model featuring enzyme-like Fe-C,N,S facial coordination has been developed. The model complex enables the bidirectional activity of H₂ activation and evolution.

A chiral ammonium salt mediates a dynamic kinetic resolution of racemic α-aryl ketones by atropselective O-alkylation. Oxidation with DDQ gives access to C₂-symmetric and non-symmetric BINOL derivatives in high yields and with high enantioselectivity.

The synthesis of well-defined planar polymers presents a significant challenge for chemists seeking to investigate their potential for use in emerging technologies. Now, a two-dimensional conjugated aromatic polymer has been synthesized via endogenous solid-state polymerization of pre-arranged monomers, and its performance as an organic anode in an ambient temperature sodium cell tested.

Amidation is one of the most widely utilized organic reactions for the synthesis of pharmaceuticals and functional materials. DATB, characterized by the B₃NO₂ heterocycle, proved to act as a superb catalyst for the direct amidation with a distinct mechanistic pathway, displaying broadened applicability to a wide range of substrates.

Covalency in actinide–­ligand bonding is poorly understood compared to that in other parts of the periodic table due to the lack of experimental data. Here, pulsed electron paramagnetic resonance methods are used to directly measure the electron spin densities at coordinated ligands in molecular thorium and uranium complexes.

2-aminothiazole — a hybrid of prebiotic amino acid and nucleotide precursors — sequentially accumulates and purifies glycolaldehyde and glyceraldehyde from complex mixtures in the order required for ribonucleotide synthesis, dynamically resolves glyceraldehyde from its ketose-isomer dihydroxyacetone, and provides the first strategy to select natural amino acids from abiotic aldehydes and ketones.

The construction of diversified compound libraries from identical substrates is attractive but remains a challenge in asymmetric synthesis. Here, we demonstrate switchable regioselective [6+2], [4+2] or [2+2] cycloadditions with α′-alkylidene-2-cyclopentenones via mild aminocatalysis, producing a spectrum of chiral frameworks with high structural diversity and molecular complexity.

NaO^tBu — an alkoxide salt — enables simple access to low-oxidation-state catalysis using sustainable first-row transition metals (Fe, Co, Mn, Ni). The approach works across a wide range of reductive alkene and alkyne functionlization reactions including hydroboration, hydrosilylation, hydrogenation, hydrovinylation and [2π+2π] cyclization reactions.

Andrea Taroni shares his experience with vanadium — a colourful element with a rich chemistry (and physics!) that is emblematic of all transition metals.