Plane overpartitions and cylindric partitions

Generating functions for plane overpartitions are obtained using various methods such as nonintersecting paths, RSK type algorithms and symmetric functions. We extend some of the generating functions to cylindric partitions. Also, we show that plane overpartitions correspond to certain domino tilings and we give some basic properties of this correspondence.     

Combining carbohydrate substitutions at bioinspired positions with multivalent presentation towards optimising lectin inhibitors: case study with calixarenes

Carbohydrate derivatisation and glycocluster formation are both known to enhance avidity for lectin binding. Using a plant toxin and human adhesion/growth-regulatory lectins (inter- and intrafamily comparisons) the effect of their combination is examined. In detail, aromatic substituents were introduced at the 2-N or 3'-positions of N-acetyllactosamine and the products conjugated to two types of calix[n]arenes (n = 4, 6) via thiourea-linker chemistry.     

SN2 Displacement of Carbohydrate Triflates by 9-Oximes of Erythromycin A and Of a Tylosin Derivative

ABSTRACT

The preparation of 9-O-glycosyloxime derivatives of erythromycin A (1) and tylosin (2) is reported. Access to this new class of macrolides was achieved from (E)-9-oxime of erythromycin A (3) and 9-oxime of tylosin 20-(1,3-dithiane) (4), by successful displacement of triflates of suitably protected carbohydrates.     

Regio‐ and Stereochemical Studies on the Nitroso‐Diels–Alder Reaction with 1,2‐Disubstituted Dienes

The regioselectivity of the nitroso‐Diels–Alder reaction between unsymmetrical acyclic dienes and Boc‐nitroso (Boc=tert‐butoxycarbonyl) reagent or the Wightman chiral chloronitroso reagents has been studied. With the Boc‐nitroso reagent, the selectivity is a consequence of steric effects at the C1‐position in the diene and electronic effects at the C2‐position in the diene. The combination of an unprotected hydroxyethyl side chain at C1 and an electron‐withdrawing group at C2 allows complete regioselectivity in favour of the proximal isomer. The same isomer was obtained exclusively with the chiral nitroso reagent with high enantioselectivities. A model based on steric effects is proposed.     

Synthesis of Ferrocenyl Schiff Bases Under Solvent-Free Conditions Using Microwave Irradiation

Ferrocenyl imines 3a–f were synthesized using solvent-free methods by mixing ferrocene carbaldehyde 1 with amines 2a–f under microwave irradiation. The imines were obtained in good yield in short reaction times.     

Building nanostructures using RAFT polymerization

Reversible addition fragmentation chain transfer (RAFT) polymerization is one of the most extensively studied controlled/living radical polymerization methods that has been used to prepare well‐defined nanostructured polymeric materials. This review, with more 650 references illustrates the range of well‐defined functional nanomaterials that can be accessed using RAFT chemistry. The detailed syntheses of macromolecules with predetermined molecular weights, designed molecular weight distributions, controlled topology, composition and functionality are presented. RAFT polymerization has been exploited to prepare complex molecular architectures, such as stars, blocks and gradient copolymers. The self‐assembly of RAFT‐polymer architectures has yielded complex nanomaterials or in combination with other nanostructures has generated hybrid multifunctional nanomaterials, such as polymer‐functionalized nanotubes, graphenes, and inorganic nanoparticles. Finally nanostructured surfaces have been described using the self‐organization of polymer films or by the utilization of polymer brushes. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Photocatalyzed Synthesis of 3-Substituted Phthalides: A Key Access to (±)-Herbaric Acid

An efficient organophotocatalyzed protocol was developed for the preparation of 3-substituted phthalides. The presented transformation was performed under particularly mild conditions within 6 h and was ultimately applied to a precursor of the herbaric acid.     

Deciphering Reversible Homogeneous Catalysis of the Electrochemical H2 Evolution and Oxidation: Role of Proton Relays and Local Concentration Effects**

Nickel bisdiphosphine complexes bearing pendant amines form a unique series of catalysts (so-called DuBois’ catalysts) capable of bidirectional/reversible electrocatalytic oxidation and production of dihydrogen. This unique behaviour is directly linked to the presence of proton relays installed close to the metal center. We report here for the arginine derivative [Ni(P₂^CyN₂^Arg)₂]⁶⁺ on a mechanistic model and its kinetic treatment that may apply to all DuBois’ catalysts and show that it allows for a good fit of experimental data measured at different pH values, catalyst concentrations and partial hydrogen pressures. The bidirectionality of catalysis results from balanced equilibria related to hydrogen uptake/evolution on one side and (metal)-hydride installation/capture on the other side, both controlled by concentration effects resulting from the presence of proton relays and connected by two square schemes corresponding to proton-coupled electron transfer processes. We show that the catalytic bias is controlled by the kinetic of the H₂ uptake/evolution step. Reversibility does not require that the energy landscape be flat, with redox transitions occurring at potentials up to 250 mV away for the equilibrium potential, although such large deviations from a flat energy landscape can negatively impacts the rate of catalysis when coupled with slow interfacial electron transfer kinetics.     

eHydrogenation: Hydrogen-free Electrochemical Hydrogenation

Hydrogenation reactions are staple transformations commonly used across scientific fields to synthesise pharmaceuticals, natural products, and various functional materials. However, the vast majority of these reactions require the use of a toxic and costly catalyst leading to unpractical, hazardous and often functionally limited conditions. Herein, we report a new, general, practical, efficient, mild and high-yielding hydrogen-free electrochemical method for the reduction of alkene, alkyne, nitro and azido groups. Finally, this method has been applied to deuterium labelling.     

Revisiting the approximate Carathéodory problem via the Frank-Wolfe algorithm

Mathematical Programming - The approximate Carathéodory theorem states that given a compact convex set $${\mathcal {C}}\subset {\mathbb {R}}^n$$ and $$p\in [2,+\infty [$$ , each point $$x^*\in...