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).
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.
Perfluoroaryl boranes are an important class of organometallic Lewis acids. The synthesis of perfluorinated compounds brings special challenges to tried‐and‐true synthetic methodologies. In their Communication on page 2955 ff., W. E. Piers and co‐workers present the synthesis of a new, fully fluorinated heterocyclic borane that is also a member of the rare antiaromatic borole class of compounds. The route relies on normally facile transmetallation reactions made more difficult by the electron‐withdrawing C6F5 groups of the target product.
Summary: New polymer gelators consisting of poly(propylene glycol) or poly(ethylene glycol) and L ‐lysine‐based low‐molecular‐weight gelators have been developed. These polymer gelators were synthesized according to a simple procedure with high reaction yield, and formed organogels in many organic solvents. The organogelation mechanism was proposed from the transmission electron microscopy and FTIR spectroscopy studies.
Structures of the polymer gelators synthesized here. 相似文献
All wrapped up : The reaction of a 22‐membered macrocycle derived from bis(o‐formylphenyl)mercury and 1,2‐phenylenediamine with palladium(II) results in cleavage of the macrocycle and concomitant formation of a trimetallic complex (see picture; phenyl rings truncated for clarity). The nature of the HgII???PdII???HgII interaction was investigated by theoretical studies.
Hooking up : FeCl2 catalyzes the efficient cross dehydrogenative arylation of substrates having benzylic C? H bonds (see scheme). High regioselectivity was observed during the cross‐coupling between compounds containing aromatic C(sp2)? H bonds and benzylic C(sp3)? H bonds. This process is proposed to proceed by single‐electron‐transfer oxidation and Friedel–Crafts alkylation.
Drei von einer Sorte : Vicinale Tricarbonyl‐Verbindungen gehen Eisen(III)‐vermittelte C‐C‐Spaltungen ein (siehe Schema). Die Ergebnisse sind relevant für den Aminosäurenachweis durch Ninhydrin und für den Vitamin‐C‐Stoffwechsel.
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.
Let the dominos fall : Synthesis of the complex DFGH ring system of the title compounds has been accomplished. The approach features simple treatment of the key intermediate with a Brønsted base to afford the tetracyclic cage‐shaped target in one pot through a four‐step domino transformation (see scheme; Mc= monochloromesylate, MOM=methoxymethyl).
It does get in! A fluoride‐assisted direct cross‐coupling of cyclic enamides with trialkoxy aryl silanes by a palladium‐catalyzed C? H activation leads to a wide range of enamides in yields of up to 95 %.
Y not? A unique, three‐coordinate Y‐shaped bis(silyl)platinum(II) complex was isolated and characterized (see structure; C light gray, N blue, Si pink, Pt dark gray). DFT studies on a model system shed light on the nature of this unusual coordination mode for platinum(II).
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.
Pick your Pd partners : A number of catalytic systems have been developed for palladium‐catalyzed C? H activation/C? C bond formation. Recent studies concerning the palladium(II)‐catalyzed coupling of C? H bonds with organometallic reagents through a PdII/Pd0 catalytic cycle are discussed (see scheme), and the versatility and practicality of this new mode of catalysis are presented. Unaddressed questions and the potential for development in the field are also addressed.
The chemical control of cell division has attracted much attention in the areas of single cell‐based biology and high‐throughput screening platforms. A mussel‐inspired cytocompatible encapsulation method for achieving a “cell‐division control” with cross‐linked layer‐by‐layer (LbL) shells is developed. Catechol‐grafted polyethyleneimine and hyaluronic acid are chosen as polyelectrolytes for the LbL process, and the cross‐linking of polyelectrolytes is performed at pH 8.5. Cell division is controlled by the number of the LbL nanolayers and cross‐linking reaction. We also suggest a new measuring unit, , for quantifying “cell‐division timing” based on microbial growth kinetics.
π–π assisted : Photoinduced electron transfer from cofacial porphyrin dimers to electron acceptors is prominently accelerated, whereas the back electron transfer is decelerated, relative to the corresponding porphyrin monomer (see figure).
“My first experiment was preparation of proline‐derived chiral ligands for asymmetric alkylation. My favorite subjects at school were history and English…?.” This and more about Keisuke Suzuki can be found on page 2635.
