Search

We have developed a new radical-mediated alkoxypolyhaloalkylation of styrenes with polychloroalkanes and alcohols for the facile synthesis of complex polyhaloalkanes. 4-Methoxybenzenediazonium tetrafluoroborate is a good radical initiator for this transformation. This protocol is well applied to the late-stage functionalization of complex molecules, including vitamin E, estrone and cholesterol derivatives. [ABSTRACT FROM AUTHOR]

Owing to their easy availability and cheapness, simple alkyl chlorides are good raw materials for introducing complex polychlorinated groups. Polychlorinated hydrocarbons units, such as di‐ or trichloromethyl groups, not only widely found in pesticide and bioactive molecule, but also can be as a precursor to converted into different functional groups such as −COOH, −CHO and −CO. The direct polychloroalkylation reaction by using simple alkyl chlrides has been considered to be an important tool for synthesizing complex polychlorinated compounds. This review summarizes recent developments, especially free radical strategies, in the polychloroalkylation of different substrates (such as 2‐acylpyridines, benzyl tertiary amines, alkenes, imine and 1,n‐enynes). We hope that this review provides a new perspective on this field and also provides a reference to develop environmentally friendly and sustainable methods. [ABSTRACT FROM AUTHOR]

The γ-lactone skeleton is very important component of various natural products, biological molecules, food additives, and perfumes. As a result, much effort has been made towards such compounds. In this review, we summarize recent progress in transition-metal-catalyzed annulation reactions for the formation of γ-lactone derivatives through a radical pathway. Various reagents, such as anhydrides, Togni's reagent, TMSN3 , arenesulfonyl chlorides, arenediazonium salts, dibenzoyl peroxides, O -benzoylhydroxylamine, NFSI, and α-halocarboxylic compounds, used in radical cyclization reactions are described, and the mechanisms of these radical annulation reactions are also discussed. 1 Introduction 2 Annulations of Alkenes with Anhydrides 3 Annulations of Unsaturated Carboxylic Acids with Nucleophiles 4 Annulations of Alkenes with α-Halocarboxylic Compounds 5 Conclusions and Outlook [ABSTRACT FROM AUTHOR]

Novel adsorbent, diethylenetriamine-grafted Spirodela polyrhiza (DSP), was synthesized via modifying natural S. polyrhiza (SP) with diethylenetriamine by cross-linking with epichlorohydrin and applied to adsorb Ni2+ and Pb2+ from water. The effecting parameters on adsorption of Ni2+ and Pb2+ such as adsorbent dosage, pH, contact time, temperature, and initial concentration were studied through equilibrium experiments. The adsorption of Ni2+ and Pb2+ followed the pseudo-second-order model and the Langmuir isotherm adsorption model. The study discusses thermodynamic parameters, including changes in Gibbs free energy, entropy, and enthalpy, for the adsorption of Ni2+ and Pb2+ on DSP, and revealed that the adsorption process was spontaneous and exothermic under natural conditions. The maximum Ni2+ and Pb2+ adsorption capacities of DSP were 33.02 and 36.50 mg/g, respectively. The newly prepared materials were characterized through scanning electron microscopy (SEM), mapping analysis, and zeta potential analysis. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analyses indicated that functional groups (-OH and N-H) were involved in Ni2+ and Pb2+ adsorption. Notably, DSP can be easily regenerated and reused for multiple cycles. Therefore, DSP is a promising adsorbent for effective Ni2+ and Pb2+ removal. [ABSTRACT FROM AUTHOR]

A new copper-catalyzed three-component oxidative 1,2-trifluoromethylarylation of styrenes with NaSO2CF3 and indoles involving aryl C–H bond functionalization is described. This reaction is initiated by single electron transfer upon utilizing TBPB as an oxidant, thus enabling introduction of a CF3 group and an aryl group into the C=C bond of alkenes in a single step. This method represents a highly atom and step-economical access to various CF3-substituted 1,1-diarylalkane derivatives in moderate to good yields with good functional group compatibility. [ABSTRACT FROM AUTHOR]

Functionalization of alkenes has been well investigated by chemists, thus it has been extensively applied in organic synthesis and industries. In the past few decades, transition‐metal, such as palladium, rhodium, gold, iridium, copper and iron, catalyzed functionalization reactions of alkenes have been significantly developed and played vital roles in synthesis. The difunctionalization of alkenes are appealing as an important alternative to the traditional approaches for the construction of useful carbon centers, particularly carbon quaternary centers, which commonly existed as structural motifs in numerous natural products, pharmaceuticals, and biologically active molecules. This account will summarize our recent advances in the intermolecular difunctionalization of alkenes, and also highlight the scope and limitations as well as the mechanisms of these difunctionalization reactions. In general, in this account the difunctionalization of alkenes starting from dicarbofunctionalization will be discussed. Then carboheterofunctionalization of alkenes will be intensively reviewed, and diheterofunctionalization will also be highlighted. This personal account introduces the recent advances in difunctionalization of alkenes. These reactions are classified by the chemical bond formation, including C−C, C−N, C−O and other carbon‐heteroatom bond formation. This review highlights the scope and limitations, as well as the mechanisms of these functionalization reactions. [ABSTRACT FROM AUTHOR]

For straightforward access to various substituted 1,1-diarylalkanes a photoredox-catalyzed and copper-promoted 1,2-alkylarylation reaction of styrenes has been developed, which uses α-carbonyl alkyl bromides and N,N-disubstituted anilines as functionalization reagents. In this radical difunctionalization reaction, α-carbonyl alkyl bromides, including primary-, secondary- and tertiary-α-bromoalkyl ketone esters, malonic esters and cycloalkane were transformed to the corresponding 1,1-diarylalkanes in moderate to good yields at room temperature. Notably, this transformation provided a new route for the C–H alkylation of N,N-disubstituted anilines with high para-selectivity beyond the typical Friedel–Crafts alkylation. [ABSTRACT FROM AUTHOR]