Bright funnels : A series of dendritic systems, which are capable of funneling energy from the periphery to the core, have been synthesized. The photophysical properties of dendrimers have been determined. Selective excitation of the donor leads to an efficient energy transfer (>90 %) to the acceptor. The approach provides a facile synthesis for the modification of near‐infrared BF2‐Azadipyrromethenes.
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.
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.
Eines der Haupttoxine bei Fischvergiftungen, das Ciguatoxin (siehe Struktur), war Ziel einer Totalsynthese. Der Syntheseweg beruht auf der Kupplung dreier Segmente, und die Schlüsselumwandlungen umfassen eine Komplexbildung zwischen Acetylen und Dicobalthexacarbonyl.
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.
Three attractions in one cage : Various magnetic networks are formed in the three polymorphs of an organic magnet, BBTDA(=benzo[1,2‐d:4,5‐d′]bis[1,3,2]dithiazole)?GaBr4. The three phases show quite different magnetic behaviors in spite of having the same chemical formula. Their magnetic differences originate from the relative configuration of the neighboring organic radical molecules in their crystals.
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.
Sleeping beauty? Is the scientific community about to kiss awake iron catalysis, a topic that has been dormant for decades? A recent study on a user‐friendly direct cross‐coupling reaction of alkyl and aryl halides constitutes an important step toward this end through the integration of two different iron‐catalyzed elementary steps into a practical one‐pot procedure.
Playing the sax : The enantioselective total syntheses of (?)‐ and (+)‐decarbamoyloxysaxitoxin (doSTX) and (+)‐saxitoxin (STX) are reported. A new methodology was developed for the synthesis of STXs, featuring discriminative reduction of the nitro group and N? O bond in nitroisoxazolidine.
A question of coordination mode : Two new borane compounds are prepared. They act as bifunctional ligands as illustrated by their reaction with ruthenium polyhydrides which leads to the formation of two complexes (see scheme) displaying either a δ‐agostic interaction of a η2‐B? H bond involving a trivalent boron atom or a dihydroborate ligation.
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.
“ Quat's” the story? N‐Aryl amides are effective directing/activating groups for chlorosilane Lewis acids. This aspect has been exploited for the development of the first simple and general method for the highly enantioselective Pictet–Spengler reaction of ketimines derived from α‐ketoamides leading to quaternary α‐amino acid derivatives (see scheme).
The cyclocondensation reaction of compound 1 in boiling hydrochloric acid had an unexpected course. Instead of supposed 5,11‐dihydro‐quinoxalino[2,3‐b]quinoline 6a , 2‐(indol‐2‐yl)‐benzimidazole 4 was isolated as the major product. 相似文献
A novel α,ω‐heterofunctional poly(ethylene oxide) (PEO) macromonomer possessing methacryloyl and thienyl end groups was prepared by ring‐opening polymerization of ethylene oxide initiated by potassium thienylethoxide and termination of the living PEO ends with methacryloyl chloride. Incorporation of methacryloyl and thienyl groups was confirmed by free‐radical and oxidative polymerization processes, respectively, and by means of 1H NMR analysis.
Long‐distance service : Finding a selective small‐molecule modulator for every domain of every human protein is a Herculean task. Wouldn't it be much easier to control the activity of any protein of choice by simply fusing it with a generally adaptable switch protein and controlling protein activity indirectly?
Simple addition : Copper(II) aqua complex 1 can be prepared in a one‐pot synthesis and is self‐assembled by H‐bond interactions. Complex 1 is shown to accelerate the nitroaldol reaction on water, which is a heterogeneous process, requiring no additive or base, and 1 can be recycled without loss of activity.
Going through the phases : The title reaction was found to proceed by an initial base‐mediated isomerization to allenyl esters and subsequent phase transfer catalyzed alkylation at the α position of the ester (see scheme).
As simple as it gets! Potassium tert‐butoxide alone catalyzes the direct dehydrogenative Si? O coupling of several synthetically important silanes with 1°, 2°, and even 3° alcohols without the need for stoichiometric hydrochloric acid scavengers. The stereoretentive mechanism is probed with a silicon‐stereogenic silane.
To Bi or not to Bi? The synthesis of phosphorus nanorods of two differing morphologies is reported, in both the presence and absence of a bismuth catalyst. Not only do these materials represent a new class of elemental nanorods but they also give valuable insight into the complex allotropy of phosphorus.
