Aqueous Coordination-Insertion Copolymerization for Producing High Molecular Weight Polar Polyolefins

Hydrocarbons, when used as the medium for transition metal catalyzed organic reactions and olefin (co-)polymerization, are ubiquitous. Environmentally friendly water is highly attractive and long-sought, but is greatly challenging as coordination-insertion copolymerization reaction medium of olefin and polar monomers. Unfavorable interactions from both water and polar monomer usually lead to either catalyst deactivation or the formation of low-molecular-weight polymers. Herein, we develop well-behaved neutral phosphinophenolato nickel catalysts, which enable aqueous copolymerization of ethylene and diverse polar monomers to produce significantly high-molecular-weight linear polar polyolefins (219-549 kDa, 0.13-1.29 mol %) in a single-component fashion under mild conditions for the first time. These copolymerization reactions occur better in water than in hydrocarbons such as toluene. The dual characteristics of high molecular weight and the incorporation of a small amount of functional group result in improved surface properties while retain the desirable intrinsic properties of high-density polyethylene (HDPE).

Synthesis and antitumor activity of a series of novel N-aryl-5-(2,2,2-trifluoroethoxy)-1,5-dihydro-2H-pyrrol-2-ones derivatives

With the help of the establishment of novel reaction methodology, a series of N-Aryl-5-(2,2,2-trifluoroethoxy)-1,5-dihydro-2H-pyrrol-2-one conjugates were designed and synthesized in 2-4 steps, and subsequent anticancer activity of these compounds was evaluated. Preliminary results showed that these compounds have moderate to potent activities against human acute leukemia cells K562, human lung cancer A549, human breast cancer MDA-MB-231, and human cervical cancer HeLa cancer cell lines. Among them, compounds 2d and 2k were the most potent against K562 cell line with IC₅₀ values of 0.07 and 0.52 µM, respectively, and the toxicity of 2d to the normal of hepatocytes (LO2) cell line was low (the survival rate 81 %). Flow cytometry analysis showed that 2d arrested K562 cells in the G2/M phase potently, even much better than Combretastatin A4 (CA4). In addition, the results demonstrated the involvement of the caspase-dependent or independent pathways of apoptosis, evidenced by the upregulation of FADD, pro-caspase 3, cleaved-caspase 3, HTRA2/Omi, SMAC/Diablo and the ratio of Bax/Bcl-2.The biological effects founding of 2d in this work point to prospective uses against acute leukemia.

Advances of Sulfenate Anions in Catalytic Asymmetric Synthesis of Sulfoxides

In recent years, sulfenate anions as key intermediates in enantioselective synthesis have attracted considerable attention. Typically, development of novel synthetic methods to generate sulfenate anions allows for the preparation of various enantiopure sulfoxides, which are prevalently used as auxiliaries, ligands, organocatalysts, and biologically active compounds. This review presents the in situ preparation methods and the recent applications of sulfenate anions in catalytic asymmetric synthesis of chiral sulfoxides.

Transition Metal/Lewis Acid Catalyzed Reactions of Zerumbone for Diverse Molecular Motifs

Zerumbone is a naturally occurring humulene type sesquiterpene, isolated from the rhizomes of Zingiber zerumbet (L.) Smith with excellent therapeutic potential and is recognized as a valuable synthon for the construction of diverse array of natural product motifs. In this review, we intended to highlight our achievements in utilizing abundant natural product zerumbone and its derivatives for the development of pharmacologically relevant molecular scaffolds. We provided an account of the transition-metal catalyzed 1,4-conjugate addition reactions of zerumbone and its derivatives along with palladium-catalyzed cross-couplings, transition metal-based Lewis acid promoted interrupted Nazarov cyclisation reaction with substituted indoles and transannular cyclizations, photo-induced transformations of zerumbone and its epoxide.

Recent Progress in the Selective Functionalization of P(O)-OH Bonds

As we all know, organic phosphorus compounds have high application values in chemical industries. Compared with traditional compounds with P-X (X = Cl, Br, I) and P-H bonds, phosphorylation reagents containing P(O)-OH bonds are stable, environmentally friendly, and inexpensive. However, in recent years, there have been few studies on the selective functionalization of P(O)-OH bonds for the fabrication of P-C and P-Z bonds. In general, four-coordinated P(O)-OH compounds have reached coordination saturation due to the phosphorus atom center, but cannot evolve the phosphorus coordination center through intra-molecular tautomerization; however, the weak coordination effects between the P=O bond and transition metals can be utilized to activate P(O)-OH bonds. This review highlights the most important recent contributions toward the selective functionalization of P(O)-OH bonds via cyclization/cross coupling/esterification reactions using transition metals or small organic molecules as the catalyst.

Transition metal catalysts for the bioorthogonal synthesis of bioactive agents

The incorporation of abiotic transition metal catalysis into the chemical biology space has significantly expanded the tool kit of bioorthogonal chemistries accessible for cell culture and in vivo applications. A rich variety of homogeneous and heterogeneous catalysts has shown functional compatibility with physiological conditions and biostability in complex environs, enabling their exploitation as extracellular or intracellular factories of bioactive agents. Current trends in the field are focusing on investigating new metals and sophisticated catalytic devices and toward more applied activities, such as the integration of subcellular, cell- and site-targeting capabilities or the exploration of novel biomedical applications. We present herein an overview of the latest advances in the field, highlighting the increasing role of transition metals for the controlled release of therapeutics.

Enamine/Transition Metal Combined Catalysis: Catalytic Transformations Involving Organometallic Electrophilic Intermediates

The concept of merging enamine activation catalysis with transition metal catalysis is an important strategy, which allows for selective chemical transformations not accessible without this combination. The amine catalyst activates the carbonyl compounds through the formation of a reactive nucleophilic enamine intermediate and, in parallel, the transition metal activates a wide range of functionalities such as allylic substrates through the formation of reactive electrophilic π-allyl-metal complex. Since the first report of this strategy in 2006, considerable effort has been devoted to the successful advancement of this technology. In this chapter, these findings are highlighted and discussed.

Recent Development of Catalytic Trifluoromethoxylation Reactions

Trifluoromethoxy (OCF₃) group exhibits unique properties, which render it a highly desirable structural motif in life and materials sciences. The numbers of newly synthesized trifluoromethyl ethers are booming as new synthetic methods are constantly being developed to access these valuable compounds. This Review summarizes recent catalytic approaches towards preparation of trifluoromethyl ethers. Alkene, allylic, benzylic, and aryl trifluoromethoxylation reactions are discussed herein.

Progress in the synthesis of δ-sultones

Abstract

Sultones, the cyclic esters of hydroxyl sulfonic acids, are a fascinating class of heterocycles and the recent years have witnessed an increasing interest in these molecules, especially in six-ring δ-sultones. The importance of these compounds is either because of their biological properties themselves or due to their versatility as intermediates in more complex target syntheses. Accordingly, the development of new synthesis methods to access δ-sultones is an important and rewarding task which we wish to highlight in this review.

Graphical abstract

Sulfur-Based Ylides in Transition-Metal-Catalysed Processes

Traditionally employed in the synthesis of small ring systems and rearrangement chemistry, sulfur-based ylides occupy a unique position in the toolbox of the synthetic organic chemist. In recent years a number of pioneering researchers have looked to expand the application of these unorthodox reagents through the use of transition metal catalysis. The strength and flexibility of such a combination have been shown to be of key importance in developing powerful novel methodologies. This chapter summarises recent developments in transition metal-catalysed sulfonium/sulfoxonium ylide reactions, as well as providing a historical perspective. In overviewing the successes in this area, the authors hope to encourage others into this growing field.

Recent Developments in the Synthesis of Cyclic Carbonates from Epoxides and CO2

The use of CO₂ as a C1 building block will be of essential importance in the future. In this context the synthesis of cyclic carbonates from epoxides and CO₂ gained great attention recently. These products are valuable compounds in a variety of chemical fields. The development of new catalysts and catalytic systems for this atom-economic, scalable, and industrially relevant reaction is a highly active research field. Over the past 17 years great advances have been made in this area of research. This chapter covers the survey of the important known classes of homogeneous catalysts for the addition of CO₂ to epoxides. Besides pioneering work, recent developments and procedures that allow this transformation under mild reaction conditions (reaction temperatures of ≤100 °C and/or CO₂ pressures of 0.1 MPa) are especially emphasized.

Recent Advances in the C-H-Functionalization of the Distal Positions in Pyridines and Quinolines

This review summarizes recent developments in the C-H-functionalization of the distal positions of pyridines, quinolines and related azaheterocycles. While the functionalization of the C2 position has been known for a long time and is facilitated by the proximity to N1, regioselective reactions in the distal positions are more difficult to achieve and have only emerged in the last decade. Recent advances in the transition metal-catalyzed distal C-H-functionalization of these synthetically-important azaheterocycles are discussed in detail, with the focus on the scope, site-selectivity and mechanistic aspects of the reactions.