Harnessing the Radical Reactivity of Silver(II) Fluoride for Organofluorine Synthesis.

Most practical fluorination reagents deliver a fluorine atom either as a nucleophile (F) or as an electrophile (F). In contrast, bench-stable radical fluorine (F) reagents are relatively less common and the vast majority of 'radical fluorinations' involve reactions of carbon-centered radicals with electrophilic fluorination reagents. Here, we disclose that silver (II) fluoride (AgF) in acetonitrile is a mild source of F that can be leveraged for the synthesis of a variety of high-value organofluorine compounds from abundantly available reactants such as alkanes, alkenes, and carboxylic acids, as well as from pharmaceutically relevant heterocycles such as indoles and benzofurans.

Probing the Oxidative Addition Transition State in Nickel Metallaphotoredox Catalysis Using Intramolecular C Kinetic Isotope Effects.

The merger of nickel and photoredox catalysis has enabled a wide range of C-C and C-X bond formations under mild conditions. Central to the mechanistic understanding of these catalytic reactions is the identification of the nickel species involved in the key oxidative addition step. Intramolecular C kinetic isotope effects (KIEs) in conjunction with DFT analysis are a reliable, quantitative approach to identify the oxidation state and ligand environment at the metal center during oxidative addition.

The Role of Aromatic Alcohol Additives on Asymmetric Organocatalysis Reactions: Insights from Theory.

The presence of an aromatic additive has been seen to enhance, often significantly, the enantioselectivity and yield in asymmetric organocatalysis. Considering their success across a dizzying range of organocatalysts and organic transformations, it would seem unlikely that a common principle exists for their functioning. However, the current investigations with DFT suggest a general principle: the phenolic additive sandwiches itself, through hydrogen bonding and π⋅⋅⋅π stacking, between the organocatalyst coordinated electrophile and nucleophile.

The "Weak" C-H⋅⋅⋅S Interaction Drives Enantioselectivity in Cinchona Alkaloid Complex Catalyzed Thiocyanation.

The great success of asymmetric organocatalysis has made it one of the most important advancements made in chemistry in the past two decades. A significant achievement in this context is the asymmetric organocatalysis of the thiocyanation reaction. In the current study, computational studies with density functional theory have been done in order to understand an interesting experimental finding: the reversal of enantioselectivity from R to S when the electrophile is changed from β-keto ester to oxindole for the thiocyanation reaction with the cinchona alkaloid complex catalyst.

Controlled reduction of isocyanates to formamides using monomeric magnesium.

This work describes a transition metal-free methodology involving an efficient and controlled reduction of isocyanates to only formamide derivatives using pinacolborane (HBpin) as the hydrogenating agent and a bis(phosphino)carbazole ligand stabilized magnesium methyl complex (1) as the catalyst. A large number of substrates undergo selective hydroboration and give exclusively -boryl formamides.

Highly Site-Selective Direct C-H Bond Functionalization of Unactivated Arenes with Propargyl α-Aryl-α-diazoacetates via Scandium Catalysis.

Highly chemo- and regio-selective C-H bond functionalization of unactivated arenes with propargyl α-aryl-α-diazoacetates has been developed using scandium catalysis. A variety of unactivated, mildly deactivated, and electronically activated arenes have been functionalized using this protocol. The synergistic combination of scandium triflate as a catalyst and propargyl α-aryl-α-diazoacetate as a reagent played a pivotal role in the effective C-H bond functionalization of arenes without the assistance of any directing group or ligand.

Catalytic Enantioselective 1,3-Alkyl Shift in Alkyl Aryl Ethers: Efficient Synthesis of Optically Active 3,3'-Diaryloxindoles.

Reported is the first organocatalytic asymmetric 1,3-alkyl shift in alkyl aryl ethers for the synthesis of chiral 3,3'-diaryloxindoles using a chiral Brønsted acid catalyst. Preliminary results showed that each enantiomer of the 3,3'-diaryloxindole, and a racemic mixture, showed different antiproliferative activities against HeLa cell lines by using an MTT assay.

A porous porphyrin organic polymer (PPOP) for visible light triggered hydrogen production.

A visible light active porphyrin-based porous organic polymer having high chemical stability and surface area has been synthesized and its ability to influence the photocatalytic activity of large band gap-TiO nanoparticles has been tested. The resultant composite shows improved photocatalytic activity as compared to the parent precursors. This study provides insights into the photosensitizing ability of the polymer in addition to its ability to firmly harbor nanoparticles onto its surface.

Interplaying anions in a supramolecular metallohydrogel to form metal organic frameworks.

The remarkable effect of anions on the transition from supramolecular gels to crystalline phases has been described. An amino acid-based metallohydrogel was transformed into different metal-organic frameworks through the selective picking of anions. The metallohydrogel and the resulting metal-organic frameworks (MOFs) were thoroughly characterized.

Odd-Even Alternation in Tautomeric Porous Organic Cages with Exceptional Chemical Stability.

Amine-linked (C-NH) porous organic cages (POCs) are preferred over the imine-linked (C=N) POCs owing to their enhanced chemical stability. In general, amine-linked cages, obtained by the reduction of corresponding imines, are not shape-persistent in the crystalline form. Moreover, they require multistep synthesis.

[3+2]-Annulation of platinum-bound azomethine ylides with distal C[double bond, length as m-dash]C bonds of N-allenamides.

A Pt-catalyzed, highly regioselective reaction between N-allenamides and imino-alkynes leading to pyrrolo[1,2-a]indoles is described. This represents the first example of [3+2]-annulation of Pt-bound azomethine ylides with the distal C[double bond, length as m-dash]C bond of N-allenamides. The mechanism of the reaction was established by computational studies.

Correlating Nitrile IR Frequencies to Local Electrostatics Quantifies Noncovalent Interactions of Peptides and Proteins.

Noncovalent interactions, in particular the hydrogen bonds and nonspecific long-range electrostatic interactions are fundamental to biomolecular functions. A molecular understanding of the local electrostatic environment, consistently for both specific (hydrogen-bonding) and nonspecific electrostatic (local polarity) interactions, is essential for a detailed understanding of these processes. Vibrational Stark Effect (VSE) has proven to be an extremely useful method to measure the local electric field using infrared spectroscopy of carbonyl and nitrile based probes.

Decoding the Morphological Diversity in Two Dimensional Crystalline Porous Polymers by Core Planarity Modulation.

Two new chemically stable triazine- and phenyl-core-based crystalline porous polymers (CPPs) have been synthesized using a single-step template-free solvothermal route. Unique morphological diversities were observed for these CPPs [2,3-DhaTta (ribbon) and 2,3-DhaTab (hollow sphere)] by simply altering the linker planarity. A detailed time-dependent study established a significant correlation between the molecular level structures of building blocks with the morphology of CPPs.

Self-Exfoliated Guanidinium-Based Ionic Covalent Organic Nanosheets (iCONs).

Covalent organic nanosheets (CONs) have emerged as functional two-dimensional materials for versatile applications. Although π-π stacking between layers, hydrolytic instability, possible restacking prevents their exfoliation on to few thin layered CONs from crystalline porous polymers. We anticipated rational designing of a structure by intrinsic ionic linker could be the solution to produce self-exfoliated CONs without external stimuli.