Ringing the changes : The total synthesis of the title compound centers around a novel strategy that employs a nickel(0)–phosphine complex and triethyl borane in an efficient closure of a 14‐membered ring through C? C bond formation (see scheme; cod=cyclooctadiene). The synthesis was accomplished in 10 steps and in approximately 9 % overall yield.
Sweets for my sweet ! Efficient synthesis of the deoxysugar part of versipelostatin (VST) was achieved by direct and stereoselective glycosidation of the reduced VST aglycon. Comparison of the synthetic and natural VST products using NMR indicate that VST has a β‐d‐digitoxose‐(1,4)‐α‐l‐oleandrose‐(1,4)‐β‐d‐digitoxose trisaccharide. A biological assay indicates that the deoxyoligosaccharide unit of the synthetic glycoside is important for biological activity.
Specific losses of water are observed from the molecular anions of monoximes of α-diketones. Labelling studies, kinetic energy release values and the +E spectra of ions have been used to aid in the elucidation of the fragmentation pathways. It is proposed that the majority of ions have α-keto nitrile structures. 相似文献
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.
Thin is in! Recent advance in solution‐phase synthesis has led to the formation of ultrathin single‐crystalline Au nanowires with diameters of less than 10 nm. This Focus Review summarizes these syntheses and provides an exciting example of the electron transport in the ultrathin Au nanowires to demonstrate their great potential for nanoelectronic applications.
?My most exciting discovery to date has been always the last one (or better still, the next one). The biggest challenge facing scientists is the responsible use of knowledge and scientific power for the betterment of humanity. …?“ This and more about P. Melchiorre can be found on page 3389.
CO! You had me at hello : The use of chiral biphenyl‐based phosphoramidite ligands on rhodium provides an efficient [2+2+2] cycloaddition between terminal alkyl alkynes and alkenyl isocyanates (see scheme). The cycloaddition proceeds through a CO migration pathway, and facilitates a rapid four‐step asymmetric synthesis of indolizidine (?)‐209D.
Monodisperse polymer gel particles with micrometer‐scale dimensions serve for a variety of applications, including those as microcapsules for actives or as micrometer‐sized matrixes for mesoscopic additives. These particles can be produced with exquisite control through the use of droplet‐based microfluidic templating followed by subsequent droplet solidification. This can be achieved by two ways: One way is to use pre‐microgel solutions of low molecular weight monomers and to form microgels by polymerizing these monomers. Another way is to use pre‐polymerized, high molecular weight precursors and to gel them by polymer‐analogous crosslinking. Both approaches have their specific advantages, allowing microgels to be tailored and optimized for specific needs such as those as delivery systems or scaffolds for living cells. This article highlights some recent achievements in the development and use of these microfluidic techniques to fabricate functional microgel particles.
Three of a kind : Vicinal tricarbonyl compounds undergo C? C cleavage mediated by ferric ions (see scheme). The observed cleavage of ninhydrin and dehydroascorbic acid has relevance for amino acid detection and the metabolism of vitamin C.
Nice coat! Organically modified silica (ormosil) is used for the ultrathin nanoprecise coating of individual multiwall carbon nanotubes using a soft‐chemistry approach. The coating layer has a uniform thickness of about 3 nm. The ormosil coating demonstrates the favorable electrical insulating properties of individual multiwall carbon nanotubes.
Perlen auf Gold : Neuartige multifunktionelle Nanopartikel bestehen aus einzelnen Amin‐modifizierten Goldnanostäbchen, an denen Fe3O4‐„Perlen“ mit Carboxyendgruppe angebracht sind. Die Partikel eignen sich zur simultanen Erkennung, dualen Bildgebung und photothermischen Ablation von Brustkrebszellen.
A series of organic‐inorganic hybrid particles were synthesized by a self‐assembled layer of different initiators, immobilized on silica particles and used for controlled radical polymerization. We use three different initiator systems for atom‐transfer radical polymerization (ATRP), unimolecular nitroxide mediated polymerization (NMP), and bimolecular NMP, for the development of the hybrid inorganic/organic particles. After preliminary qualitative characterization by X‐ray spectroscopy (XPS) and Fourier‐transformed infrared (FT‐IR) measurements, the hybrid nanoparticles were studied by thermogravimetric analysis (TGA) to determine and discuss the initiator graft density in terms of steric hindrance.
The coupling agents employed for the various approaches used here: a) NMP1‐bimolecular system, b) NMP2‐unimolecular system, and c) ATRP. 相似文献
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.
