Throw your hat in the ring : A highly diastereoselective synthesis of the ABC rings of (?)‐norzoanthamine has been achieved starting from the (?)‐Hajos–Parrish ketone (see scheme). Three asymmetric quaternary carbon centers on the C ring were constructed by a 1,4‐addition, and an intramolecular Diels–Alder reaction provided a trans‐decalin scaffold on the AB rings.
Quality control : The incorporation of a wrong amino acid into a growing polypeptide chain induces a correction step in which the release factor (RF1) hydrolyzes the peptide from the incorrectly matched peptidyl‐tRNA (see picture). The nascent erroneous polypeptide is released from the ribosome and degraded.
Taking shortcuts : A remarkably short and high‐yielding asymmetric total synthesis of (?)‐oseltamivir takes advantage of organocatalysis and single‐pot domino operations. The target, known as the drug Tamiflu, is prepared efficiently in a short time, and also its derivatives can be synthesized effectively.
Attraktives Chlor : Nichtkovalente Wechselwirkungen zwischen Chlor‐ oder Brom‐Atomen und aromatischen Ringen in Proteinen bieten einen neuen Ansatzpunkt für die Beeinflussung der molekularen Erkennung. Die Einführung dieser Substituenten an spezifischen Positionen zweier Faktor‐Xa‐Inhibitoren erhöht deren freie Bindungsenergie durch die Wechselwirkung mit einer Tyrosineinheit. Das allgemeine Vorkommen dieses Strukturmotivs wird anhand zahlreicher Kristallstukturen und quantenchemischer Rechnungen belegt (siehe Bild).
Mark us bent! The synthesis, structure, and single‐ and two‐photon spectroscopic properties of a series of pyrimidine‐based (bent‐shaped) molecules are reported. These allow structure‐property relationships and guidelines for both the development and application of TPA compounds to be derived.
A different drummer : The existence of endohedral germanium clusters was predicted earlier by gas‐phase experiments. The [Co@Ge10]3? anion now synthesized is surprising, as it breaks with a long line of exclusively deltahedral structures found in the past. Instead, it has a regular pentagonal‐prismatic structure (see picture; Co gray, Ge red).
The stabilisation of miniemulsions using an in situ generated surfactant is presented. This surfactant, prepared from of a water‐soluble base and an oil‐soluble long chain acid was successfully used to create stable miniemulsions with up to 60 vol.‐% organic phase. It is shown that the creation of a surface active species at the oil–water interface allowed stable miniemulsions to be generated more rapidly than when using conventional surfactant. In addition, polymerised miniemulsions exhibited less secondary nucleation when in situ surfactants were used.
A breakthrough in the asymmetric hydroboration of notoriously difficult 1,1‐disubstituted alkenes using a new family of highly effective hydroboration reagents is described (see scheme). The intermediate boranes can be oxidized to alcohols or used in Suzuki–Miyaura cross‐coupling reactions.
Ordered water : Gypsum has been used for construction for millennia. The structure and water content of calcined gypsum, CaSO4?0.5 H2O, has been under discussion until now: single‐crystal structure analysis (see picture: S yellow, Ca gray, O blue, H red) provides an ordered model that is confirmed by DFT calculations.
Additional cyclization : Dicyanonitrosomethanide, [C(CN)2(NO)]? undergoes nucleophilic addition and cyclization of 1,2‐diaminoethane and 1,3‐diaminopropane on the nitrile groups to form imidazolinyl and 1,4,5,6‐tetrahydropyrimidinyl groups, respectively. Ethanolamine has lower reactivity and fails to cyclize.
Improving on Mother Nature? The carbohydrate recognition demonstrated by supramolecular systems in water can now compete with that of natural systems, both in terms of affinity and selectivity. A synthetic carbohydrate receptor displays similar affinity for N‐acetyl‐D ‐glucosamine derivatives as the lectin wheat germ agglutinin and even greater selectivity (see picture: gray C, white H, blue N, red O).
No need for a metal : A combination of mass spectrometry and computational studies (density functional theory and coupled‐cluster methods) shows that [P4O10].+ is the first polynuclear nonmetal oxide cation that is capable of activating the C? H bond of methane at room temperature (see picture). This process represents a further example in the reactivity of oxygen‐centered radicals.
“My first experiment was the Wittig reaction to prepare chiral allenes. If I wasn′t a scientist, I would be a historian. …?” This and more about Yoshiaki Nishibayashi can be found on page 4276.
