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Although samarium-mediated cyclizations have the potential to generate significant molecular complexity, historically it has not proven possible to exert enantiocontrol through the use of a chiral ligand in complex product synthesis. Now, an enantioselective SmI2-mediated radical cyclization has been developed using a chiral aminodiol ligand. Desymmetrizing 5-exo ketyl-alkene cyclizations and cyclization cascades of unsaturated ketoesters deliver complex products and typically proceed with high enantioselectivity and diastereoselectivity.
Catalysis involving high-valent metals is an important facet of modern chemistry, but tools for catalyst development in this field have lagged behind those for low-valent systems. Now, an experimental system that can accurately model and predict reactivity has been developed to aid high-valent catalyst design.
Mononuclear gold(II) complexes are very labile (and thus very rare) species. Now, a gold(II) porphyrin complex has been isolated and characterized, and its reactivity towards dioxygen, nitrosobenzene and acids investigated. Owing to a second-order Jahn–Teller distortion, the gold atoms were found to adopt a 2+2 coordination mode in a planar N4 environment.
Realization of the bicyclic aromaticity has attracted much attention because of the potential to modulate the fundamental properties of 3D aromatic organic molecules that are not topologically planar. Now, the synthesis and characterization of dual-aromatic molecules, and their electronically mixed [4n+1]/[4n+1] triplet bi-radical species displaying Baird-type aromaticity, has been realized.
A chemical proteomic strategy has now been reported for the global profiling of lysine reactivity and ligandability. Using this approach, >9000 lysines in the human proteome were evaluated, leading to the discovery of hyper-reactive lysines, and lysines that can be targeted by electrophilic small molecules to perturb enzyme function and protein–protein interactions.
Delayed resolution of G-quadruplexes during replication can induce localized loss of epigenetic information and changes in gene expression. Now, this effect has been used to discover biologically potent G-quadruplex ligands and to demonstrate that G-quadruplex stabilization can induce epigenetic changes that are heritable across cell divisions even after the ligand is removed.
Bacterial naphthoquinone meroterpenoid natural products defy biosynthetic logic via classical biochemical paradigms. Now, an enzyme promoted α-hydroxyketone rearrangement catalysed by vanadium-dependent haloperoxidases reveals a conserved biosynthetic reaction in this molecular class that further has inspired a concise biomimetic synthesis of naphthomevalin, a prominent member of the napyradiomycin meroterpenes.
Supramolecular heterostructures have been formed by the sequential deposition of two molecular layers with different symmetries and lattice constants — one consisting of carboxylic acid, the other of cyanuric acid and melamine — on a hexagonal boron nitride substrate. Characterization by atomic force microscopy and molecular dynamics simulations shows epitaxial arrangements between the layers.
Woven topologies endow macroscopic objects with mechanical stability, but their molecular counterparts have remained difficult to prepare. Now, an extended triaxial supramolecular weave has been formed by the self-assembly of a judiciously shaped organic building block — a rigid oligoproline segment featuring two perylene-monoimide moieties — through π–π stacking and CH–π interactions.
Creating systems that merge some of the advantages of both heterogeneous and molecular catalysis is a useful approach to developing improved catalysts. Following this strategy, a liquid mixture of gallium and palladium supported on porous glass has now been shown to form an active catalyst for alkane dehydrogenation that is resistant to coke formation and is thus highly stable.
The collective synthesis of several oligomeric polypyrroloindoline natural products, including hodgkinsine, hodgkinsine B, idiospermuline, quadrigemine H and isopsychotridines B and C, is accomplished through the iterative action of an asymmetric small molecule copper catalyst. This strategy also enables the synthesis of putatively unnatural quadrigemine H-type isomers.
Amines are commonly occurring units in many biologically active molecules. Now, a catalytic method has been developed that merges an unprotected/unactivated ketimine, a monosubstituted allene and a commercially available diboron reagent to afford versatile α-tertiary amines in up to 95% yield, >98% diastereomeric ratio and >99:1 enantiomeric ratio. The utility of this method was demonstrated through its application to the synthesis of the tricyclic core of a class of compounds with anti-Alzheimer activity.
Modular hybridization probes (M-Probes) have been developed that enable sequence-selective binding of complex nucleic acid targets. The M-probes can target sequences that: are hypervariable at prescribed loci, are long continuous sequences of over 500 nucleotides, or contain repetitive sequences. A hybrid-capture assay using the M-probes was developed that was capable of determining the exact triplet repeat expansion number in the Huntington's gene from genomic DNA.
Photoprotection is crucial for the fitness of organisms that carry out oxygenic photosynthesis. LHCSR, a photosynthetic light-harvesting complex, has been implicated in photoprotection in green algae and moss. Now, single-molecule studies of LHCSR have revealed that multi-timescale protein dynamics underlie photoprotective dissipation of excess energy.
Delivery of antibodies into living cells enables the labelling and manipulation of intracellular antigens; however, transporting antibodies into the cytosol in a functional state is difficult. Now, a modular strategy for creating cell-permeable nanobodies capable of targeting intracellular antigens has been developed. The cell-permeable nanobodies are formed by site-specific attachment of cyclic arginine-rich cell-penetrating peptides to camelid-derived single-chain antibody fragments.
The transition state governs how bonds form and cleave during a reaction — its direct characterization is a long-standing challenge. Now, the F + CH3OH → HF + CH3O reactive surface has been studied using photoelectron velocity-map imaging spectroscopy of cryo-cooled anions, revealing vibrational Feshbach resonances and bound states supported by the post-transition-state potential well. The experiments agree well with quantum dynamical calculations.
Current mineral-based theories do not fully address how enzymes emerged from prebiotic catalysts. Now, iron–sulfur clusters can be synthesized by UV-light-mediated photolysis of organic thiols and photooxidation of ferrous ions. Iron–sulfur peptides may have formed easily on early Earth, facilitating the emergence of iron–sulfur-cluster-dependent metabolism.
Octameric complexes of serine are long known for their special properties, such as their enhanced stability and preference for homochirality. Yet, there is no consensus on their structures. Now, experimental data on the serine octamer–dichloride complex is presented that supports a highly symmetrical, highly stable structure.
A metallo–DNA hybrid nanowire composed only of silver-mediated base pairs has been prepared and its crystal structure resolved by X-ray diffraction. The nanowire, which is 2 nm wide and whose length reaches the μm to mm scale, holds silver ions into uninterrupted one-dimensional arrays along the DNA helical axis.
Several natural and unnatural lissoclimide cytotoxins have been prepared via semi-synthesis and total synthesis. An X-ray co-crystal structure of chlorolissoclimide with the ribosome and evaluation of cytotoxicity and translation inhibition of new compounds in the series improves our understanding of the molecular basis for cytotoxicity.
