The wide occurrence of pyrroles in natural products and pharmaceuticals calls for novel synthetic methodologies for the efficient synthesis of enantiopure pyrroles. Owing to their highly reactive ...nature and wide‐ranging chemical landscape, enormous efforts have been dedicated not only to their synthesis but also to the development of reactions using them as a platform and their utilization in the stereocontrolled synthesis of diverse molecules. In sharp contrast to the extensive studies devoted toward indoles, the asymmetric functionalization of pyrroles was less explored. Nevertheless, the attractiveness of pyrroles for their selective functionalization to access natural product analogy, and medicinally useful architectures have witnessed tremendous growth in the last few years. Their effectiveness under both metal‐ and organocatalytic conditions currently encompasses a vast majority of enantioselective transformations. This review article aims to present a comprehensive overview of the catalytic asymmetric C−H as well as N−H functionalization of pyrroles reported from 2010 to now.
This review aims to present a comprehensive overview of the catalytic asymmetric C−H as well as N−H functionalization of pyrroles reported from 2010 to now. Pyrroles have unique reactivity and tremendous efforts have been made not only for their synthesis but also for the development of reactions using them as the synthons and their utilization in the stereocontrolled synthesis of complex molecules.
Catalytic formation of borylamines from atmospheric N2 is achieved for the first time using a series of homogenous (triphosphine)Mo complexes. Stepwise functionalization of the ...(triphosphine)Mo‐nitrido complex with chloroborane led to the synthesis of the imido complex. Electrochemical characterization of the (PPP)Mo‐nitrido and (PPP)Mo‐borylimido complexes showed that the latter is much more easily reduced.
Catalytic formation of N−B bonds from atmospheric N2, chloroboranes and electrons is achieved with (triphosphine)molybdenum complexes.
•Critical and comparative review on CO2 adsorbents functionalized by amine-bearing polymers.•Functionalization by polyamines to meet multiple capture performance requirements.•Various polymer ...functionalities reviewed used to functionalize a variety of solid adsorbents.•The results and comparisons listed aim to help researchers tune performance at specific capture conditions.•Grafting at molecular precision, in-situ evaluation, combinations of amine types, and hybrid scaffolds are proposed.
Efforts to capture CO2 from anthropogenic sources as well as from the air are being continuously intensified as to battle the greenhouse gas effects and climate change. Capture by liquid solvent absorption, mainly involving amines, is the common industrial practice, yet capture relying on solid adsorbents is increasingly gaining interest due to its potential for less energy-demanding and more efficient operation. Despite the large variety of porous adsorbents being explored, such as zeolites, carbons, mesoporous silicas, graphene and related structures, polymers, and metal-organic frameworks, it still remains challenging to find a proper material to cover all the critical specifications, i.e. with respect to CO2 capacity, selectivity, chemical and thermal stability, fast kinetics, cyclability, low energy consumption, low manufacturing cost, and mechanical robustness. To this end, combining highly CO2-phylic amines with the most robust of the developed solid porous materials through functionalization of the latter is a highly promising approach. Consequently, particular emphasis is given to increase the number of amine functional groups per unit of support area, enhance CO2-phylicity of the amines, and provide suitable diffusion pathways to enhance CO2 capacity. Towards achieving this goal, use of amine-bearing polymer functionalities is being highly investigated. This work critically and comparably reviews current progress on polymeric amine - functionalized solid adsorbents and their performance in CO2 capture. It examines works based on various polymers, including polyethylenimine, polypropylenimine, polyallylamine, polyaniline, amino dendrimers, and hyperbranched polyamines. Based on the extracted comparisons, optimal systems are proposed and envisioned and future trends and directions are stated.
New directions: The carboxylic acid functional group directs the ortho acylation of benzoic acids with carboxylic anhydrides in the presence of a rhodium catalyst (see scheme; ...cod=cyclo‐1,5‐octadiene). The acylation at the ortho position is complementary to the meta selectivity of Friedel–Crafts reactions. The resulting products can undergo protodecarboxylation to deliver an aryl ketone.
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•Transferrin-functionalized liposomes loaded with DTX have been successfully obtained.•Liposomes with nanometric size, spherical morphology and sustained release of DTX.•LIP-DTX-TF ...showed higher uptake than non-functionalized liposomes by prostate cancer cells.•The interaction of liposomes with receptors overexpressed on the surface of the tumor cells was demonstrated by QCM-D.
Prostate cancer (PC) is the second type of cancer, causing the greatest number of deaths among the male population in the world. An attractive approach to treat PC involves the superficial modification of liposomes with specific ligands to overexpressed receptors on the surfaces of tumor cells, such as transferrin receptors (TFR’s). To our knowledge, this is the first time that transferrin-functionalized liposomes for delivery of DTX to prostate cancer cells were investigated. In this study, we developed and characterized docetaxel- loaded liposomes functionalized with transferrin (LIP-DTX-TF) and evaluated their effect on PC cell lines. The results showed that the systems had a nanometric size and the presence of DTX contributed to the reduction of the vesicle size and liposomes were stable. The encapsulation efficiency of DTX was approximately 69 and 37 % for liposomes with and without functionalization, respectively. The functionalization efficiency using TF was 31 %. The functionalization process did not affect the integrity of TF. DTX encapsulated in the liposomes showed slow and sustained release for LIP-DTX and LIP-DTX-TF (51.70 % and 31.97 %, respectively). The in vitro cytotoxicity assay in PC-3 and PNT2 cell lines suggest that LIP-DTX-TF was more toxic to PC-3 than the commercial formulation. Confocal microscopy proved that functionalized liposomes were successfully internalized in PC-3 cells. Furthermore, the interaction of these systems with the TFR’s overexpressed on the cell surface was further corroborated using Quartz Crystal Microbalance with Dissipation technology (QCM-D). Therefore, although additional studies in three-dimensional cell models and in vivo xenograft studies are warranted, it can be concluded that the systems developed here are promising candidates for the delivery of docetaxel to prostate cancer cells.
Oxidative R1–H/R2–H cross-coupling represents an ideal way for the construction of new chemical bonds. However, the bond formation with loss of H2 is typically thermodynamically unfavorable and thus ...usually requires an external driving force, namely, an appropriate sacrificial oxidant. Recent advances have revealed that oxidative R1–H/R2–H cross-coupling with hydrogen gas evolution can be achieved through electrochemical anodic oxidation and concomitant cathodic proton reduction. Electrochemistry provides new opportunities for the construction of carbon-carbon and carbon-heteroatom bonds in an environmentally friendly manner. This review article gives an overview of the recent developments in this emerging field.
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The ideal way for organic synthesis is to develop methods by using only green energy without the generation of chemical waste. This review article discusses the use of electrochemistry to promote the bond formation of readily available organic materials, namely, electrochemical dehydrogenative cross-coupling. No sacrificial reagent is required, and hydrogen gas is the only by-product during the reaction. In addition, only electric energy is consumed during the synthetic process. This is a fast-developing research area but is still in its infancy. In this review, we discuss the recent achievements of utilizing electrochemical oxidation in dehydrogenative C–H/C–H cross-coupling, dehydrogenative C–H/X–H cross-coupling, and dehydrogenative annulation.
This review provides an overview of a green way to construct new chemical bonds by using electrochemical methods. This reaction protocol avoids the use of sacrificial reagents and produces hydrogen gas as the only by-product. It offers new opportunities for organic synthesis in an environmentally friendly manner.
Biopolymer aerogels were among the first aerogels produced, but only in the last decade has research on biopolymer and biopolymer–composite aerogels become popular, motivated by sustainability ...arguments, their unique and tunable properties, and ease of functionalization. Biopolymer aerogels and open‐cell foams have great potential for classical aerogel applications such as thermal insulation, as well as emerging applications in filtration, oil–water separation, CO2 capture, catalysis, and medicine. The biopolymer aerogel field today is driven forward by empirical materials discovery at the laboratory scale, but requires a firmer theoretical basis and pilot studies to close the gap to market. This Review includes a database with over 3800 biopolymer aerogel properties, evaluates the state of the biopolymer aerogel field, and critically discusses the scientific, technological, and commercial barriers to the commercialization of these exciting materials.
Air gel: The last decade has seen a strong acceleration in biopolymer and biopolymer–composite aerogel research, motivated by sustainability arguments, their unique and tunable properties, and ease of functionalization. This Review evaluates the field of biopolymer aerogels, including its potential and barriers for applications in thermal insulation, filtration, oil–water separation, CO2 capture, catalysis, drug delivery, and nutrition.
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