Volume 1 Issue 6, June 2018

Inexpensive, earth-abundant photoabsorbers for solar water splitting have, so far, not demonstrated notable performance. Now, voltage gained from a coaxial heterojunction coupled with nanostructure-enhanced photocurrent results in Cu₂O photocathodes demonstrating benchmark water-splitting performance.

Although the replacement of palladium with iron in metal-catalysed cross-couplings continues apace, the Suzuki synthesis of biaryls — arguably the most widely used class of such C–C bond formations — has remained elusive. Now, by use of a π-coordinating directing group, another step has been taken toward iron-catalysed Suzuki reactions.

The need for new single enantiomer drug substances helps drive the development of new asymmetric catalytic synthetic methods. A new enantioconvergent process enabled by an ionization racemization mechanism allows a hydrogenative route to chiral compounds with two stereocentres.

The carboxylation of aromatic compounds with CO₂ is an attractive reaction, albeit limited in scope. Now, bulky ligands in a Rh(II) catalysed C–H carboxylation of 2-arylphenols are shown to override the standard ortho/para Kolbe–Schmitt-type regioselectivity allowing instead carboxylation at 2’.

Iron–sulfur metalloproteins are widespread and efficient catalysts for multielectron reduction of small molecules. Now, research shows that simple Fe₄S₄ cofactors and related complexes can perform effective reductive chemistry producing small hydrocarbons from CO₂ and CO.

Single-atom catalysts have drawn increasing attention as methods for their preparation and characterization improve. Here, Beller and co-workers discuss the latest developments in the field of single-metal-site catalysts, discussing how this catalyst class bridges heterogeneous and homogeneous catalysis, and providing a perspective on how the field might continue to develop.

The conversion of methanol — which can be produced from non-fossil resources — to important chemical commodities such as olefins and aromatics allows for the diversification of organic feedstocks beyond petrochemicals. This Review covers recent discoveries about the mechanism of this process and discusses how these link to practical aspects in reaction engineering.

The generation of hydrogen fuel from water and visible light requires photoelectrodes that are inexpensive, stable and highly active. Now, Luo, Grätzel and co-workers report Cu₂O photocathodes that reach these goals. Incorporation into an unassisted solar water splitting device gives ~3% solar-to-hydrogen conversion efficiency.

The conversion of carbon dioxide into multi-carbon alcohols would enable the synthesis of sustainable liquid fuels with high energy densities. Now, vacancy-engineered core–shell copper-based catalysts are able to shift the selectivity of electrochemical CO₂ reduction into alcohols instead of alkenes, as obtained with bare-copper catalysts.

Cross-coupling of aryl compounds is one of the most powerful carbon–carbon bond forming reactions available, and typically involves the use of expensive and scarce palladium salts. Here Bedford and co-workers show that iron can be an effective catalyst for Suzuki biaryl couplings.

Dynamic kinetic resolution (DKR) allows the conversion of both enantiomers of a racemic mixture into a single enantiomer of product, and requires both a stereoselective reaction and a means of rapidly racemizing the starting materials. Here, a highly stereoselective iridium-catalysed DKR of secondary allylic alcohols is reported, with mechanistic studies implying that substrate racemization is achieved through carbon–oxygen bond cleavage.

The Fe protein of nitrogenase contains a redox-active [Fe₄S₄] cluster that plays a key role in electron transfer and substrate reduction. Here, Hu and co-workers show that the Fe protein of Methanosarcina acetivorans can reduce CO₂ and CO to hydrocarbons under ambient conditions.

Alcohols serve as versatile intermediates for the synthesis of pharmaceuticals and other valuable compounds. Here, Contente and Paradisi developed self-sustainable biocatalytic flow systems for the conversion of amines into various non-commercially-available and high-value alcohols.

The structural modification of inactive materials to effectively engineer active catalysts is very attractive. Here, layered crystalline Pd₃P₂S₈ is transformed by electrochemical lithiation into amorphous Li-incorporated nanodots. This process turns the inert parent material into a highly active and stable hydrogen-evolving catalyst.

Catalytic arene carboxylation with CO₂ is a challenging reaction, with limited substrate scope and selectivity. Now, a redox neutral method based on a ligand-assisted Rh-catalysed C–H activation is shown, which features broad scope and provides access to important and biologically relevant structural motifs