A light touch is all that is required to cleave a maleimide C? N bond to effect a [5+2] photocycloaddition with a sterically encumbered C?N moiety (see scheme).
Cooperative metal centers in a bimetallic catalyst facilitate the highly enantioselective ring opening of meso aziridines 1 with silyl nucleophiles (see scheme; TMS=trimethylsilyl). The 1,2‐azidoamides 2 and 1,2‐amidonitriles 3 obtained in this way in high yields and with up to 99 % ee are valuable precursors to enantiomerically pure 1,2‐diamines and β‐amino acids.
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.
How are dihydropyridines like indoles? Both groups of compounds have similar nucleophilicity parameters N and are therefore suitable substrates for iminium‐catalyzed reactions of α,β‐unsaturated aldehydes. The N parameters of 1,4‐dihydropyridines were derived from the rates of hydride transfer reactions to benzhydrylium ions (see scheme).
Conditional cleavage : Photochemical S? N bond cleavage of the Zn2+ complex of N‐dansylcyclen (ZnL2) in aqueous solution was investigated. Moreover, photolysis of ZnL2 (see scheme) facilitated photoreversion of cis,syn‐thymine photodimer (T[c,s]T).
Inorganic enzyme? Ceria nanoparticles exhibit unique oxidase‐like activity at acidic pH values. These redox catalysts can be used in immunoassays (ELISA) when modified with targeting ligands (see picture; light blue and yellow structures are nanoparticles with attached ligands). This modification allows both for binding and for detection by the catalytic oxidation of sensitive colorimetric dyes (e.g. TMB).
All done! A full account of the total synthesis of ouabagenin and ouabain has been described. The synthesis was achieved through a polyanionic cyclization strategy. Degradation studies provide an ultimate proof for a key intermediate observed in the synthesis.
Macrolide magic : An enyne cross‐metathesis reaction of an alkynyl boronate with an alkene derivative as well as a radical cyclization reaction of a homopropargylic β‐alkoxyacrylate are the key transformations in the total synthesis of the cytotoxic macrolide (?)‐amphidinolide K.
Total synthesis through block glycosylation and selective chemical O‐sulfation of tyrosine residues yielded the glycopeptide recognition domain A (X=SO3?) of the P‐selectin glycoprotein ligand 1, in which the terminal sialic acid of the complex hexasaccharide side chain was replaced by (S)‐cyclohexyl lactic acid. In binding assays the O‐sulfated structure A showed high affinity towards P‐selectin, the non‐sulfated towards E‐selectin.
Weaving an intricate web : A stereoselective synthesis of (?)‐agelastatin A has been developed, which requires 11 steps from commercially available starting material. The application of a Rh‐catalyzed intramolecular olefin aziridination reaction and the subsequent manipulation of the resulting tricyclic intermediate (see scheme) punctuate this study.
Preferred protonation : Does electrospray ionization mass spectrometry produce gas‐phase or liquid‐phase structures? The preferred protonation site in p‐aminobenzoic acid depends upon the medium, and the structure of its conjugate acid varies with the solvent used during spraying.
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.
“ 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).
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.
Doped up : The incorporation of Zn2+ dopants in tetrahedral sites leads to the successful magnetism tuning of spinel metal ferrite nanoparticles (see picture). (Zn0.4Mn0.6)Fe2O4 nanoparticles exhibit the highest magnetization value among the metal ferrite nanoparticles. Such high magnetism results in the largest MRI contrast effects (r2=860 mm?1 s?1) reported to date and also huge hyperthermic effects.
