Photoinduced Copper‐Catalyzed Coupling of Terminal Alkynes and Alkyl Iodides

We have developed a photoinduced copper‐catalyzed alkylation of terminal alkynes with primary, secondary, or tertiary alkyl iodides as electrophiles. The reaction has a broad substrate scope and can be successfully performed in the presence of ester, nitrile, aryl halide, ketone, sulfonamide, epoxide, alcohol, and amide functional groups. The alkylation is promoted by blue light (λ≈450 nm) and proceeds at room temperature in the absence of any additional metal catalysts. The use of a terpyridine ligand is essential for the success of the reaction and is shown to prevent photoinduced copper‐catalyzed polymerization of the starting materials.     

Metal-Free Hydrosilylation of Ketenes with Silicon Electrophiles: Access to Fully Substituted Aldehyde-Derived Silyl Enol Ethers

Little-explored hydrosilylation of ketenes promoted by main-group catalysts is reported. The boron Lewis acid tris(pentafluorophenyl)borane accelerates the slow uncatalyzed reaction of ketenes and hydrosilanes, thereby providing a convenient access to the new class of β,β-di- and β-monoaryl-substituted aldehyde-derived silyl enol ethers. Yields are moderate to high, and Z configuration is preferred. The corresponding silyl bis-enol ethers are also available when using dihydrosilanes. The related trityl-cation-initiated hydrosilylation involving self-regeneration of silylium ions is far less effective.     

On the impact of suboptimal decisions in the newsvendor model

We study the impact of suboptimal decisions in the newsvendor model, one of the popular inventory models. We establish a lower bound for the deviation of inventory cost from its minimum, when the order quantity is suboptimal. Demonstration of the bound shows the model to be sensitive to suboptimal decisions.     

$$\mathsf {CENCPP}^*$$ CENCPP ∗ : beyond-birthday-secure encryption from public permutations

Designs, Codes and Cryptography - Public permutations have been established as important primitives for the purpose of designing cryptographic schemes. While many such schemes for authentication...     

Fluorescent detection of cholesterol using β-cyclodextrin functionalized graphene

A fluorescence based cholesterol detection method has been developed using competitive host-guest interaction between graphene bound β-cyclodextrin (β-CD) with rhodamine 6G (R6G) and cholesterol. Fluorescence of β-CD incorporated R6G is quenched by graphene but is 'turned on' by cholesterol as it replaces R6G from the β-CD host.     

An inventory model with partial backordering and unit backorder cost linearly increasing with the waiting time

As the implementation of JIT practice becomes increasingly popular, each echelon in a supply chain tends to carry fewer inventories, and thus the whole supply chain is made more vulnerable to lost sales and/or backorders. The purpose of this paper is to recast the inventory model to be more relevant to current situations, where the penalty cost for a shortage occurrence at a downstream stage in a supply chain is continually transmitted to the upstream stages. The supplier, in this case, at the upstream of the supply chain is responsible for all the downstream shortages due to the chain reaction of its backlog. The current paper proposes a model in which the backorder cost per unit time is a linearly increasing function of shortage time, and it claims that the optimal policy for the supplier is setting the optimal shortage time per inventory cycle to minimize its total relevant cost in a JIT environment.     

Aryl azo imidazole assisted self-assembly of d metal complexes: Influence of halogen substitution and counter ions

A series of eight coordination networks has been obtained by the self-assembly of the aryl azo imidazole based building block and with d¹⁰ metal [Zn(II), Cd(II), and Hg(II)] and counter anion (Cl⁻, NO₃⁻, SCN⁻) in order to rationalize the effect of coordination behavior of the metal ion, the size of the anions and the substitution effects of ligands upon the structure adopted by these metal complexes. Influences of halogen (Cl⁻, Br⁻, and I⁻) substitutions are reflected in the precise molecular level architecture in the individual complexes. The parameters related to the coordination sphere depend on the metal-to-ligand ratios and are also influenced by the solvent of crystallization. A competition between the coordinating capabilities of the counter anion with ligands and its shape led to neutral and anionic metal complexes. Furthermore, various physicochemical studies viz. thermal behaviors, absorption spectra have been conducted to rationalize their structure in solution phase.     

Synthesis of a Counteranion‐Stabilized Bis(silylium) Ion

The preparation of a molecule with two alkyl‐tethered silylium‐ion sites from the corresponding bis(hydrosilanes) by two‐fold hydride abstraction is reported. The length of the conformationally flexible alkyl bridge is crucial as otherwise the hydride abstraction stops at the stage of a cyclic bissilylated hydronium ion. With an ethylene tether, the open form of the hydronium‐ion intermediate is energetically accessible and engages in another hydride abstraction. The resulting bis(silylium) ion has been NMR spectroscopically and structurally characterized. Related systems based on rigid naphthalen‐n,m‐diyl platforms can only be converted into the dications when the positively charged silylium‐ion units are remote from each other (1,8 versus 1,5 and 2,6).