Heterocycles made green: New methodologies for the synthesis of pyrroles were recently developed based on domino Ir- and Ru-catalyzed amination and alkylations of alcohols. The concept provides a greener approach to interesting N-heterocyclic compounds.

Inner workings: The X-ray crystal structure of the entire bacterial complex I at 3.3 Å resolution offers fascinating insights into a giant 536 kDa molecular machine. The respiratory chain complex seems to employ unique mechanisms of energetic coupling that are entirely different from those found in all other enzymes using redox energy to drive vectorial proton transport across a bioenergetic membrane.

One metal or two? Recent results in the design of hydrogenase mimics have resulted in NiFe- and Fe-based complexes (see picture) that split molecular H₂ into electrons and protons. Although these compounds are still far from technological application they improve our understanding of how nature exploits abundant metals to achieve complex reactions.

Line up for synthesis! In a recent report the Leigh group described a rotaxane-based setup for the sequence-specific synthesis of small peptides, which runs automatically once started. This molecular machine combines elements from both chemical and biochemical peptide (bio-)syntheses, which are discussed in this Highlight.

Modern chemistry with an old substituent: The introduction of the SCF₃ group into organic substrates is a challenging task because of harsh or specific synthetic methods. However, recent advances in the formation of CSCF₃ bonds include the trifluoromethylthiolation with transition-metal-free systems or in the presence of palladium, nickel, or copper catalysts (see scheme).

Inexpensive copper(I) catalysts allow the direct site-selective azidation (CN bond formation) of C(sp²)H bonds in electron-rich heteroarenes and readily available anilines (see scheme). The reaction occurs under remarkably mild conditions and has a broad substrate scope.

Lewis acid and oxidation catalysis are merged in the reaction discussed here, which provides access to diversely substituted N-hydroxycarbamates (see scheme). This reaction highlights the potential of nitrosoformates as electrophilic amination reagents as well as the benefits of aerobic oxidation for the formation of highly reactive species.

Bringing to light: The rediscovery of visible light as an abundant energy source for organic reactions has most recently brought copper-catalyzed coupling reactions to the center of attention. This Highlight summarizes the most significant advancements in the field of CC and CN coupling reactions in which covalent copper–substrate complexes are photo-activated.

In silico veritas? Maybe not the whole truth, but very helpful suggestions and guidelines for the experimental work can be deduced from computational studies on Rh-catalyzed [3+2+1] cycloaddition reactions for the construction of cis-fused bicyclohexenones from alkylidenecyclopropanes and carbon monoxide.

Free rein: Advances in transition-metal-free direct amination of aryl boronic acids and their derivatives have been recently described (see scheme). These reactions are based on the use of hydroxylamine or azide derivatives and offer great potential for further applications.

All things graphene: Within the graph of graphene one finds subgraphs for a myriad of novel aromatic hydrocarbons. For example, defining the vertices of a C3 subgraph within graphene evokes higher-order structures simply by changing the length of the ring fusion links. Analogously, the C6 transformation yields coronene and kekulene (see scheme).

How about this for a change: The promiscuous enzyme cytochrome P450-BM3 catalyzes the cyclopropanation of olefins, sometimes with high stereoselectivity (see scheme). The highlighted paper demonstrates that it is possible to design unusual enzyme promiscuity.

Different but almost equal: The striking similarities between Brookhart's iridium(III) pincer complex and the electron-deficient tris(pentafluorophenyl)borane in transformations involving SiH bond activation are highlighted. Coordination of the SiH bond to either Lewis acid enhances the electrophilicity of the silicon atom, thereby enabling its transfer to various Lewis basic groups (see scheme, Do=acetone).

On the way to membranes for the separation of industrially important gas pairs, researchers have devised the new ladder polymer PIM-EA-TB, which was found to have remarkable selectivity and permeability for several technically relevant gas pairs. A possible explanation of these observations is given.

The heat is on: A new [3+2] cycloaddition/cycloreversion strategy allows for catalytic and thermally allowed carbonyl–olefin metathesis (see scheme). This strategy opens opportunities for new developments in the field of carbonyl–olefin metathesis, which traditionally relied on stoichiometric amounts of transition-metal reagents or photochemical promotion.

Totally rad: Synthetic methods have been developed for the formation of C_sp3F bonds by reaction of C-centered radicals with fluorine sources. Three complementary strategies, which differ in the mode of generation of the alkyl radical intermediate, are described. These include olefin hydrofluorination, decarboxylative fluorination, and aliphatic CH fluorination.

Pressed for results: Mechanical forces can be used to generate reactive small molecules, such as mineral acids and hydrogen peroxide, from appropriately designed polymeric materials. These novel mechanically responsive scaffolds set the foundation for using mechanochemistry to access new classes of self-healing materials and to drive small-scale synthetic reactions.

Chiral possibilities (Cp): In two approaches for introducing chirality into reactions of half-sandwich Rh complexes, dihydroisoquinolones have been synthesized from benzamides and olefins. In one approach C₂-symmetric Cp ligands were utilized, while in the other an artificial metalloenzyme was employed as the chiral catalyst, leading to high levels of enantioselectivity.

Sticking together: Colloidal particles with a determined number of sticky sites arranged in precise geometries analogous to atoms were created. The kinetics of the colloidal assemblies related to specific chemical reactions (see figure) were investigated using optical microscopy. This general method should allow for a broad range of useful 3D colloidal assemblies.

Finally isolated: The isolation of a nitridophosphane(V) was described for the first time by the research group of Bertrand. The reactivity and the possibility of stabilizing labile R₂PN/R₂NP species (see structure) are discussed.