Nova Reader - Subject

Catalysis with Palladium(I) Dimers

2020-12-10T00:00

Dinuclear Pd^I complexes have found widespread applications as diverse catalysts for a multitude of transformations. Initially their ability to function as pre‐catalysts for low‐coordinated Pd⁰ species was harnessed in cross‐coupling. Such Pd^I dimers are inherently labile and relatively sensitive to oxygen. In recent years, more stable dinuclear Pd^I−Pd^I frameworks, which feature bench‐stability and robustness towards nucleophiles as well as recoverability in reactions, were explored and shown to trigger privileged reactivities via dinuclear catalysis. This includes the predictable and substrate‐independent, selective C−C and C−heteroatom bond formations of poly(pseudo)halogenated arenes as well as couplings of arenes with relatively weak nucleophiles, which would not engage in Pd⁰/Pd^II catalysis. This Minireview highlights the use of dinuclear Pd^I complexes as both pre‐catalysts for the formation of highly active Pd⁰ and Pd^II−H species as well as direct dinuclear catalysts. Focus is set on the mechanistic intricacies, the speciation and the impacts on reactivity.

While dinuclear Pd^I complexes first received attention for being excellent pre‐catalysts that lead to high cross‐coupling reactivities, more recent work has uncovered that direct dinuclear catalysis can also take place and reaction modes are accessible which are not amenable to Pd⁰/Pd^II cycles. This Minireview highlights the use of dinuclear Pd^I complexes in catalysis showcasing their unique reactivity and selectivity.

Molecularly Imprinted Polymer Nanoparticles: An Emerging Versatile Platform for Cancer Therapy

2020-11-23T00:00

Molecularly imprinted polymers (MIPs) are chemically synthesized affinity materials with tailor‐made binding cavities complementary to the template molecules in shape, size, and functionality. Recently, engineering MIP‐based nanomedicines to improve cancer therapy has become a rapidly growing field and future research direction. Because of the unique properties and functions of MIPs, MIP‐based nanoparticles (nanoMIPs) are not only alternatives to current nanomaterials for cancer therapy, but also hold the potential to fill gaps associated with biological ligand‐based nanomedicines, such as immunogenicity, stability, applicability, and economic viability. Here, we survey recent advances in the design and fabrication of nanoMIPs for cancer therapy and highlight their distinct features. In addition, how to use these features to achieve desired performance, including extended circulation, active targeting, controlled drug release and anti‐tumor efficacy, is discussed and summarized. We expect that this minireview will inspire more advanced studies in MIP‐based nanomedicines for cancer therapy.

This minireview surveys recent advances in research on molecularly imprinted polymer nanoparticles (nanoMIPs) for cancer therapy and highlights the distinct features of nanoMIPs for the rational design and construction of cancer nanomedicines with desired performances, including extended circulation, active targeting, controlled drug release, and antitumor efficacy.

Frustrated Radical Pairs: Insights from EPR Spectroscopy

2020-11-17T00:00

Progress in frustrated Lewis pair (FLP) chemistry has revealed the importance of the main group elements in catalysis, opening new avenues in synthetic chemistry. Recently, new reactivities of frustrated Lewis pairs have been uncovered that disclose that certain combinations of Lewis acids and bases undergo single‐electron transfer (SET) processes. Here an electron can be transferred from the Lewis basic donor to a Lewis acidic acceptor to generate a reactive frustrated radical pair (FRP). This minireview aims to showcase the recent advancements in this emerging field covering the synthesis and reactivities of frustrated radical pairs, with extensive highlights of the results from Electron Paramagnetic Resonance (EPR) spectroscopy to explain the nature and stability of the different radical species observed.

Single or Double? This Minireview highlights the recent new reactivities of frustrated Lewis pairs that disclose that certain combinations of Lewis acids and bases undergo single‐electron transfer processes. In these studies, Electron Paramagnetic Resonance spectroscopy has been instrumental in the elucidation of reaction pathways.

Recent Advances in Catalytic Hydrosilylations: Developments beyond Traditional Platinum Catalysts

2020-12-01T00:00

Hydrosilylation reactions, which allow the addition of Si−H to C=C/C≡C bonds, are typically catalyzed by homogeneous noble metal catalysts (Pt, Rh, Ir, and Ru). Although excellent activity and selectivity can be obtained, the price, purification, and metal residues of these precious catalysts are problems in the silicone industry. Thus, a strong interest in more sustainable catalysts and for more economic processes exists. In this respect, recently disclosed hydrosilylations using catalysts based on earth‐abundant transition metals, for example, Fe, Co, Ni, and Mn, and heterogeneous catalysts (supported nanoparticles and single‐atom sites) are noteworthy. This minireview describes the recent advances in this field.

This minireview describes recent advancements in catalysts for the hydrosilylation of olefins and alkynes. Emphasis is given on developments of alternative catalyst systems such as non‐noble metal complexes and heterogeneous catalysts.

Radical‐Based Synthesis and Modification of Amino Acids

2020-11-04T00:00

Amino acids (AAs) are key structural motifs with widespread applications in organic synthesis, biochemistry, and material sciences. Recently, with the development of milder and more versatile radical‐based procedures, the use of strategies relying on radical chemistry for the synthesis and modification of AAs has gained increased attention, as they allow rapid access to libraries of novel unnatural AAs containing a wide range of structural motifs. In this Minireview, we provide a broad overview of the advancements made in this field during the last decade, focusing on methods for the de novo synthesis of α‐, β‐, and γ‐AAs, as well as for the selective derivatisation of canonical and non‐canonical α‐AAs.

This Minireview provides a broad overview of the advancements made in the synthesis and modification of amino acid derivatives using radical chemistry during the last decade. The overview is divided in two sections: methods for the de novo synthesis of α‐, β‐, and γ‐amino acids, and methods for the selective derivatisation of canonical and non‐canonical α‐amino acids.