First Higher‐Order Photocycloaddition to a CN Bond: 1,3‐Diazepines from Maleimides

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).

     

A Sequential O‐Nitrosoaldol and Grignard Addition Process: An Enantio‐ and Diastereoselective Entry to Chiral 1,2‐Diols

Chiral 1,2‐diols have been prepared from α‐aminoxylated aldehydes or cyclohexanone and Grignard reagents with L ‐proline or its tetrazole derivative as the catalyst. The presence of the ate complex of CeCl₃?2 LiCl is essential for the high overall yields and good selectivities (see scheme; DMSO=dimethyl sulfoxide, THF=tetrahydrofuran, Tol=tolyl).

     

A Ditopic Ion‐Pair Receptor Based on Stacked Nucleobase Quartets

Pass the salt, please! State‐of‐the‐art computations indicate that the stacking complex of a guanine quartet and an adenine quartet (G₄A₄) can function as a potent ditopic receptor for NaCl in aqueous solution (see picture; Na⁺, Cl^? yellow, O red, N blue, C black, H white).

     

Palladium‐Catalyzed Substitution of Allylic Fluorides

As unusual substrates for the Tsuji–Trost allylation reaction, allylic fluorides are responsive to palladium‐catalyzed substitution. Their activity towards this reaction fits in the series OCO₂Me>OBz? F ?OAc. The classic stereoretention mechanism that involves sequential inversions does not operate in this case. Several distinct cases are considered.

     

High Catalytic Activity of Palladium(II)‐Exchanged Mesoporous Sodalite and NaA Zeolite for Bulky Aryl Coupling Reactions: Reusability under Aerobic Conditions

Exchange for the better : Mesoporous sodalite and NaA zeolite exchanged with Pd²⁺ exhibit remarkably high activity and reusability in C? C coupling reactions under aerobic atmosphere. It is proposed that the catalytic reactions are mediated by a molecular Pd⁰ species generated in situ within the pores (see picture), which is oxidized back to Pd²⁺ by O₂, preventing the formation of catalytically inactive Pd⁰ agglomerates.

     

Total Synthesis of (−)‐ and (+)‐Decarbamoyloxysaxitoxin and (+)‐Saxitoxin

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.

     

Epoxide‐Opening Cascades in the Synthesis of Polycyclic Polyether Natural Products

The structural features of polycyclic polyether natural products can, in some cases, be traced to their biosynthetic origin. However in case that are less well understood, only biosynthetic pathways that feature dramatic, yet speculative, epoxide‐opening cascades are proposed. We summarize how such epoxide‐opening cascade reactions have been used in the synthesis of polycyclic polyethers (see scheme) and related natural products.

     

Gold‐Catalyzed Homogeneous Oxidative Cross‐Coupling Reactions

Oxidizing gold? A gold(I)/gold(III) catalytic cycle is essential for the first oxidative cross‐coupling reaction in gold catalysis. By using Selectfluor for gold(I) oxidation, this chemistry reveals the synthetic potential of incorporating gold(I)/gold(III) catalytic cycles into contemporary gold chemistry and promises a new area of gold research by merging powerful gold catalysis and oxidative metal‐catalyzed cross‐coupling reactions.

     

Gas‐Phase versus Liquid‐Phase Structures by Electrospray Ionization Mass Spectrometry

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.

     

Magneto‐Structural Correlations in a 1,3,2‐Dithiazolyl Radical Crystal,BBDTA⋅GaBr4: Structure and Magnetic Properties of its Three Polymorphs

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.

     

Olive‐Shaped Chiral Supramolecules: Simultaneous Self‐Assembly of Heptameric Lanthanum Clusters and Carbon Dioxide Fixation

Cluster's last stand : Six chiral reduced Schiff base ligands containing amino acids and seven La^III ions self‐assemble to form a novel heptameric lanthanum supramolecule with the aid of the CO₃^2? ion (see picture). The cluster exists as a single chiral triple helix. The CO₃^2? ion, which is derived from atmospheric CO₂ , adopts a rare μ₃‐tridentate bridging mode that links three La^III ions, thus allowing the cluster to efficiently fix CO₂.

     

Computer‐Aided Design of a Sulfate‐Encapsulating Receptor

Custom built : A promising new approach towards more efficient self‐assembled cage receptors through computer‐aided design is demonstrated. The resulting M₄L₆ tetrahedral cage, internally functionalized with accurately positioned urea hydrogen‐bonding groups (see structure; yellow: predicted, blue: experimental, space‐filling: SO₄^2?), proved to be a remarkably strong sulfate receptor in water.

     

High‐Yielding Synthesis of the Anti‐Influenza Neuramidase Inhibitor (−)‐Oseltamivir by Three “One‐Pot” Operations

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.

     

Darstellung und Eigenschaften von Ti-substituierten N-Heterocyclen

Preparation and Properties of Ti-substituted N-Heterocycles The compounds (x = 2 to 6) have been prepared by transamination of Ti(NMe₂)₄ with the heterocyclic amines and have been characterised by elemental analyses and ¹H NMR and IR spectroscopy. The dependence on both x and n of the thermal decomposition has been studied for the series and . The results can be interpreted in terms of the steric strain of the R₂N and substituents. Apart from the piperidido groups none of the ligands exhibit protective group properties comparable to the R₂N groups.     

UV/Vis to NIR Photoconduction in Cyclopalladated Complexes

Funky discotics : Photoconductivity is measured in newly synthesized cyclopalladated metallomesogens exhibiting hexagonal columnar mesophases at room temperature. The tuning of the HOMO/LUMO energy levels by modification of the chain/core linkage (ester 1 vs ether 2 ) makes compound 2 photoconductive across the whole UV/Vis/NIR range.

     

Facile Synthesis and Systematic Investigations of a Series of Novel Bent‐Shaped Two‐Photon Absorption Chromophores Based on Pyrimidine

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.

     

Critical Enhancements of MRI Contrast and Hyperthermic Effects by Dopant‐Controlled Magnetic Nanoparticles

Doped up : The incorporation of Zn²⁺ dopants in tetrahedral sites leads to the successful magnetism tuning of spinel metal ferrite nanoparticles (see picture). (Zn_0.4Mn_0.6)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.