This review seeks to provide coverage on the recent advances in chiral squaramide‐catalyzed asymmetric transformations and their applications in the synthesis of a variety of chiral biologically active compounds. It aims to give an overview highlighting the new reaction types and enantioenriched medicinal scaffolds developed in the last few years.
Our journey in organophosphorus research over the past 26 years is compiled in this Personal Account. Advances in palladacycle design have engendered a shift in our focus from template‐mediated transformations to catalysis for the direct preparation of chiral phosphines containing a wide variety of functional groups. Novel approaches to access previously inaccessible phosphines and their applications in cancer research are summarized herein.
Nanometer‐sized metal particles constitute an unavoidable family of catalysts, combining the advantages of molecular complexes in regards to their catalytic performances and the ones of heterogeneous systems in terms of easy recycling. As part of this research, our group aims at designing well‐defined metal nanoparticles based‐catalysts, in non‐conventional media (ionic liquids or water), for various catalytic applications (hydrogenation, dehalogenation, carbon‐carbon coupling, asymmetric catalysis) in mild reaction conditions. In the drive towards a more eco‐responsible chemistry, the main focuses rely on the search of highly active and selective nanocatalysts, in association with an efficient recycling mainly under pure biphasic liquid‐liquid conditions. In this Personal Account, we proposed our almost fifteen‐years odyssey in the world of metal nanoparticles for a sustainable catalysis.
Electron‐deficient enamines such as enaminones and enaminoesters are moieties showing widespread application in organic synthesis. Among the various available electron‐deficient enamines, the N,N‐disubstituted amino‐functionalized ones (tertiary enamines) represent a class of special enamines with distinct properties and important applications. Based on our longstanding interest in exploring novel synthetic methods using electron‐deficient tertiary enamines, we present herein the research advances in organic synthesis via domino reactions making use of the combinatorial C–N, C=C, C–H, and other bond transformations of electron‐deficient tertiary enamines.
Asymmetric hydrogenation is one of the most efficient and atom‐economical tools to prepare chiral molecules. However, the enantiodiscrimination of simple, minimally functionalized olefins is still challenging and requires more sophisticated ligand design. Herein, we discuss our progress in the successful development of ligand design for the iridium‐catalyzed asymmetric hydrogenation of minimally functionalized olefins.
Rhodamine hydrazides and hydroxamates derived from hydrazines and hydroxylamines have been applied as fluorescent chemosensors. Reaction‐based irreversible probes based on the specific chemical reactions of reactive target species have been developed and applied in bio‐imaging studies. The strong chelation frames provided by the rhodamine hydrazides and hydroxamates have been utilized for the monitoring of metal ions, amino acids, and reactive acid derivatives. This Personal Account focuses on our perspective of developing fluorescent probes based on rhodamine hydrazides and hydroxamates.
The feasibilities of Fujita's unit‐subduced‐cycle‐index (USCI) approach, Fujita's proligand method, and Fujita's stereoisogram approach have been demonstrated by applying them to cubane derivatives as probes. They provide us with a new set of theoretical foundations for comprehensive investigation of geometric and stereoisomeric features of stereochemistry. The new set of theoretical foundations is based on mathematical formulations so as to explore mathematical stereochemistry as a new interdisciplinary field of stereochemistry.
Zeolites with intricate micropores have been widely studied for a long time as an important class of porous materials in different areas of industrial processes such as gas adsorption and separation, ion exchange, and shape‐selective catalysis. However, their industrial syntheses are not sustainable, and normally require the presence of expensive organic templates and a large amount of solvents such as water. The presence of organic templates not only increases zeolite cost but also produces harmful gases during the removal of these templates by calcination, while the use of solvents significantly increases the amount of polluted water. This Personal Account briefly summarizes recent sustainable routes for the synthesis of zeolites in our group according to our understanding of the synthetic mechanism, and mainly focuses on the organotemplate‐free synthesis of zeolites in the presence of zeolite seeds, the design of environmentally friendly templates, and solvent‐free synthesis of zeolites.
This article describes recent developments in C3‐symmetric tris‐urea low‐molecular‐weight gelators and their applications. The C3‐symmetric tris‐ureas are excellent frameworks to form supramolecular polymers through noncovalent interactions. In organic solvents, hydrophobic tris‐ureas form supramolecular gels. Amphiphilic tris‐ureas form supramolecular gels in aqueous media. Functional supramolecular gels were prepared by introducing appropriate functional groups into the outer sphere of tris‐ureas. Supramolecular hydrogels obtained from amphiphilic tris‐ureas were used in the electrophoresis of proteins. These electrophoreses results showed several unique characteristics compared to typical electrophoreses results obtained using polyacrylamide matrices.
Transition‐metal complex triplet photosensitizers are versatile compounds that have been widely used in photocatalysis, photovoltaics, photodynamic therapy (PDT) and triplet–triplet annihilation (TTA) upconversion. The principal photophysical processes in these applications are the intermolecular energy transfer or electron transfer. One of the major challenges facing these triplet photosensitizers is the short triplet‐state lifetime, which is detrimental to the above‐mentioned photophysical processes. In order to address this challenge, transition‐metal complexes showing long‐lived triplet excited states are highly desired. This review article summarizes the development of this fascinating area, including the molecular design rationales, the principal photophysical properties, and the applications of these complexes in PDT and TTA upconversion.
This focus review summarizes our recent efforts on the synthetic applications of bithiophene dicarbanions generated from three bithiophene isomers: 2,2′‐, 3,3′‐, and 2,3′‐bithiophene. Based on these bithiophene dicarbanions, a series of dithienothiophenes ( DTT s) and cyclooctatetrathiophenes ( COTh s) were synthesized by intra‐ and intermolecular cyclizations, respectively. Moreover, recent applications of DTT and COTh in characteristic compounds such as dendrimers, thio[8]circulenes, double helicenes, and thienoacenes are summarized in this account. Besides the synthetic work, some photoelectric properties of the thiophene‐based oligomers including organic field‐effect transistors and organic photovoltaics are briefly reviewed.
Monometallic and dimetallic complexes with the ruthenium‐amine conjugated structural unit have been prepared. These complexes display consecutive redox waves with low potentials and rich and intense absorptions in the near‐infrared region. The electrochemical and spectroscopic properties can be modulated using substituents or auxiliary ligands with different electronic natures. Through simple functionalization, electropolymerized or monolayer thin films of these complexes have been prepared. These films display multistate near‐infrared electrochromism with good contrast ratios and long optical retention times. In addition, flip‐flop and flip‐flap‐flop memories have been demonstrated on the basis of these thin films.
Multisubstituted olefins are fundamental motifs in organic compounds. In this account, we describe the synthesis of organic molecules bearing an olefinic moiety by the transition‐metal‐catalyzed regio‐ and stereoselective addition of a variety of interelement compounds to alkynes. Regio‐ and stereoselective silaboration, diborylation, and chlorothiolation have been achieved by using the transition‐metal catalysts. The subsequent cross‐coupling reactions of the boron‐containing alkenes to install various aryl groups afforded the corresponding tri‐ and tetraarylated olefins. This account describes our research on the highly regio‐ and stereoselective synthesis of multifunctionalized olefins such as tetraarylethenes with four different aryl groups.
For efficient photoresponses of liquid‐crystal (LC) azobenzene (Az) polymer systems, planar LC orientation of the Az mesogenic group is required because the light irradiation process usually occurs with normal incidence to the film surface. However, LC molecules with a rodlike shape tend to orient perpendicularly to the film surface according to the excluded volume effect theory. This review introduces new approaches for inducing planar orientation in side‐chain LC Az polymer films via interface and surface molecular designs. The planar orientation offers efficient in‐plane photoalignment and photoswitching to hierarchical LC architectures from molecular LC mesogens and LC phases to mesoscopic microphase‐separated structures. These approaches are expected to provide new concepts and possibilities in new LC polymer devices.
There is a great need for effective transformations and a broad range of novel chemical entities. Continuous‐flow (CF) approaches are of considerable current interest: highly efficient and selective reactions can be performed in CF reactors. The reaction setup of CF reactors offers a wide variety of possible points where versatility can be introduced. This article presents a number of selective and highly efficient gas–liquid–solid and liquid–solid reactions involving a range of reagents and immobilized catalysts. Enantioselective transformations through catalytic hydrogenation and organocatalytic reactions are included, and isotopically labelled compounds and pharmaceutically relevant 1,2,3‐triazoles are synthesized in CF reactors. Importantly, the catalyst bed can be changed to a solid‐phase peptide synthesis resin, with which peptide synthesis can be performed with the utilization of only 1.5 equivalents of the amino acid.
We present herein a personal account of our achievements in the development of novel catalytic systems based on late‐transition‐metal complexes for the hydroarylation of alkynes. In particular, our targets were intermolecular hydroarylation reactions with arene or heteroarene substrates devoid of directing groups. We have shown that complexes of palladium, platinum or gold with N‐heterocyclic carbene (NHC) ligands can be particularly useful catalysts for this reaction; the NHC ligand imparts greater stability to the complex and renders the catalytic system more productive. Furthermore, we have identified promoters and reaction media that allow to significantly improve the catalytic activity under mild conditions, to control the reaction chemoselectivity and to steer it towards more complex products; thus making this reaction considerably more attractive for the synthetic chemist.
In contrast to the conventional group transfer polymerization (GTP) using a catalyst of either an anionic nucleophile or a transition‐metal compound, the organocatalyzed GTP has to a great extent improved the living characteristics of the polymerization from the viewpoints of synthesizing structurally well‐defined acrylic polymers and constructing defect‐free polymer architectures. In this article, we describe the organocatalyzed GTP from a relatively personal perspective to provide our colleagues with a perspicuous and systematic overview on its recent progress as well as a reply to the curiosity of how excellently the organocatalysts have performed in this field. The stated perspectives of this review mainly cover five aspects, in terms of the assessment of the livingness of the polymerization, limit and scope of applicable monomers, mechanistic studies, control of the polymer structure, and a new GTP methodology involving the use of tris(pentafluorophenyl)borane and hydrosilane.
Aggregation‐induced emission (AIE) luminogens show abnormal fluorescent behavior; they are non‐emissive in solution, but they become strongly emissive after aggregation. Sensing and imaging are the major applications of AIE luminogens. By properly manipulating the aggregation and deaggregation of AIE molecules, various bio‐/chemosensors have been developed. Moreover, AIE molecules with targeting groups have been devised for imaging of organelles and cancer cells. In this account, we report our recent work on the application of AIE luminogens for the construction of bio‐/chemosensors and imaging.
Graft copolymers with a conducting polymer backbone are a promising class of materials for diverse applications including, but not limited to, organic electronics, stimuli‐responsive surfaces, sensors, and biomedical devices. These materials take advantage of the unique electrochemical and optoelectronic properties of conducting polymers, complemented by chemical and/or physical properties of the grafted sidechains. In this Personal Account, we discuss our work in designing functional surfaces based on graft copolymers with a conducting polymer backbone, in the context of broader developments in the field. We review the synthetic approaches available for the rational design of conducting‐polymer‐based graft copolymers, and examine the types of functional surfaces and soluble materials that may be engineered using these techniques.
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