Articles in 2012

Comparing how cyclopropanated polymers with different backbones behave when stretched with an atomic force microscope reveals that it is not only the strained rings that influence the mechanochemical response, but that the structure of the polymer backbone itself is far from innocent in this regard.

Polymer mechanochemistry can trigger a wide range of often unanticipated reactivity, but the focus of these systems typically falls on the structure of the mechanophore rather than the intervening polymer backbone. Now, it has been shown that a poly(norbornene) backbone has a substantial impact on a mechanochemical ring-opening reaction, despite having only a minor effect on the force-free reaction.

A hydrindanone-based approach to yohimbinoid natural products has been developed. A judicious choice of reaction conditions — inspired by prior work by the Stork group — allows effective control of the stereochemistry at C3 of the yohimbinoid skeleton. This approach has resulted in the first total syntheses of the C3 epimeric natural products venenatine and alstovenine.

The metal cofactors responsible for the activity of CDK2 — a representative member of the kinase superfamily of enzymes — have now been shown to also have inhibitory effects during the catalytic cycle.

Quantum mechanics rears its head in many places and one of them is inorganic chemistry, where the electronic spin associated with unpaired electrons has a profound influence. This was the topic of the 2012 CECAM workshop.

Daniel Rabinovich outlines the history, properties and uses of aluminium — one of the most versatile, pervasive and inexpensive metals today, yet it was considered a rare and costly element only 150 years ago.

Natural products contain a range of chemical structures optimized for biological interactions. Fragmenting these compounds could help to combine this diversity with the broad coverage of chemical space offered by fragment-based drug discovery, and help to improve the efficiency with which screening hits can become successful drugs.

An experimental set-up has been devised to monitor mechanochemical processes in situ, yielding direct insights into mechanistic and kinetic aspects of solid-state reactions that are promoted by grinding, such as the synthesis of metal–organic frameworks.

Bruce Gibb discusses how and why chemists name reactions and molecules — and what makes such monikers stick.

The biosynthesis of peptidoglycan is an important step in bacterial cell division and cell-wall maturation. Now it has been shown that fluorescent D-amino acids can be used to label the peptidoglycan cell wall of living bacteria, providing a new tool to study this important process.

The oxidation of methane to create useful feedstocks is hampered by over-oxidation when using O₂. Now a process using gaseous sulfur as a ‘soft’ oxidant for selective conversion to ethylene over metal sulfide catalysts has been developed. Simulations show that both methane activation and ethylene selectivity is linearly correlated with catalyst metal-sulfur bond strength.

A form of π backbonding is observed in a π-diborene complex of platinum, and confirmed by calculations. This interaction partially fills a bonding π orbital on the diborene ligand, strengthening the B–B bond. That π backbonding can strengthen bonds overturns ingrained notions that π backbonding is exclusively a bond-weakening phenomenon.

A 24 π-electron antiaromatic hexaphyrin derivative (rosarin) with a near-planar geometry enforced by bridging phenylene groups has been shown to undergo a proton-coupled electron transfer reduction when treated with certain protic acids. The reduction proceeds in a stepwise fashion to give first a 25 π-electron non-aromatic system and then a 26 π-electron aromatic ring.

Natural products populate areas of chemical space not occupied by average synthetic molecules. Here, an analysis of more than 180,000 natural product structures results in a library of 2,000 natural-product-derived fragments, which resemble the properties of the natural products themselves and give access to novel inhibitor chemotypes.