15 research outputs found

    Copper-Catalyzed Cascade Radical Addition–Cyclization Halogen Atom Transfer between Alkynes and Unsaturated α‑Halogenocarbonyls

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    A Cu-catalyzed cascade radical addition/cyclization/halogen atom transfer between alkynes and α-halogeno-γ, δ-unsaturated carbonyl compounds for the synthesis of various substituted cyclopentenes is described. Since up to four Csp<sup>3</sup>–Csp<sup>2</sup> bonds, two Csp<sup>3</sup>–Br bonds, and two carbocycles can be established in a single reaction, this 100% atom-efficient reaction exhibits the advantages of wide substrate scope, high functional group tolerance, and step-economics, and it offers an entry of the atom transfer radical addition/cyclization (tandem ATRA-ATRC) process to the synthesis of substituted cyclopentenes

    A Cascade Phosphinoylation/Cyclization/Desulfonylation Process for the Synthesis of 3‑Phosphinoylindoles

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    3-Phosphinoylindole derivatives play important roles as pharmaceutical drugs and ligands. A new method for the synthesis of 3-phosphinoylindole derivatives has been achieved through silver-mediated cycloaddition between N-Ts-2-alkynylaniline derivatives and H-phosphine oxides. This transformation offers a straightforward route to the formation of the C–P bond, indole ring, and desulfonylation in one step

    Highly Sensitive and Specific Multiplexed MicroRNA Quantification Using Size-Coded Ligation Chain Reaction

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    As important regulators of gene expression, microRNAs (miRNAs) are emerging as novel biomarkers with powerful predictive value in diagnosis and prognosis for several diseases, especially for cancers. There is a great demand for flexible multiplexed miRNA quantification methods that can quantify very low levels of miRNA targets with high specificity. For further analysis of miRNA signatures in biological samples, we describe here a highly sensitive and specific method to detect multiple miRNAs simultaneously in total RNA. First, we rationally design one of the DNA probes modified with two ribonucleotides, which can greatly improve the ligation efficiency of DNA probes templated by miRNAs. With the modified DNA probes, the ligation chain reaction (LCR) can be well applied to miRNA detection and as low as 0.2 fM miRNA can be accurately determined. High specificity to clearly discriminate a single nucleotide difference among miRNA sequences can also be achieved. By simply coding the DNA probes with different length of oligo (dA) for different miRNA targets, multiple miRNAs can be simultaneously detected in one LCR reaction. In our proof of principle work, we detect three miRNAs: let-7a, mir-92a, and mir-143, which can also be simultaneously detected in as small as 2 ng of total RNA sample

    Synthesis of <i>S</i>‑Aryl Phosphorothioates by Copper-Catalyzed Phosphorothiolation of Diaryliodonium and Arenediazonium Salts

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    Green methods for the synthesis of <i>S</i>-aryl phosphorothioates have been developed based on copper-catalyzed multicomponent reactions involving diaryliodonium/arenediazonium salts, elemental sulfur, and R<sub>2</sub>P­(O)H compounds. Most target products are obtained with these two methods in good to high yields at room temperature. These transformations allow the direct formation P–S and C–S bonds in one reaction

    Cascade Phosphinoylation/Cyclization/Isomerization Process for the Synthesis of 2‑Phosphinoyl‑9<i>H</i>‑pyrrolo[1,2‑<i>a</i>]indoles

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    Pyrrolo­[1,2-<i>a</i>]­indole is a common structural motif found in many natural products and pharmaceuticals. A silver-mediated oxidative phosphinoylation of <i>N</i>-propargyl-substituted indoles was used to construct a variety of 2-phosphinoyl-9<i>H</i>-pyrrolo­[1,2-<i>a</i>]­indoles under mild conditions. This transformation offers a straightforward route to the formation of the C–P bond, cyclization, and isomerization in one step

    Copper-Catalyzed P‑Arylation via Direct Coupling of Diaryliodonium Salts with Phosphorus Nucleophiles at Room Temperature

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    A new method for copper-catalyzed P–C bond formation through reaction of phosphorus nucleophiles with diaryliodonium salts at room temperature is described. Most target products are obtained with this method in high yields within a short reaction time of 10 min. It can be easily adapted to large-scale preparations. When unsymmetrical iodonium salts are employed, nucleophilic substitution occurs preferentially on the sterically hindered aromatic ring or the more electron-deficient ring

    <i>tert</i>-Butyl Hydroperoxide Mediated Cascade Synthesis of 3‑Arylsulfonylquinolines

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    3-Arylsulfonylquinoline derivatives play important roles as pharmaceutical drugs. A new method for the synthesis of 3-arylsulfonylquinoline derivatives has been achieved through <i>tert</i>-butyl hydroperoxide mediated cycloaddition between <i>N</i>-propargyl aromatic amine derivatives and arylsulfonylhydrazides without the addition of any metals. This transformation offers a straightforward route to the formation of a C–S bond and quinoline ring in one step via a sulfonylation–cyclization–aromatization process

    Cationic Conjugated Polymers-Induced Quorum Sensing of Bacteria Cells

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    Bacteria quorum sensing (QS) has attracted significant interest for understanding cell–cell communication and regulating biological functions. In this work, we demonstrate that water-soluble cationic conjugated polymers (PFP-G2) can interact with bacteria to form aggregates through electrostatic interactions. With bacteria coated in the aggregate, PFP-G2 can induce the bacteria QS system and prolong the time duration of QS signal molecules (autoinducer-2 (AI-2)) production. The prolonged AI-2 can bind with specific protein and continuously regulate downstream gene expression. Consequently, the bacteria show a higher survival rate against antibiotics, resulting in decreased antimicrobial susceptibility. Also, AI-2 induced by PFP-G2 can stimulate 55.54 ± 12.03% more biofilm in <i>E. coli</i>. This method can be used to understand cell–cell communication and regulate biological functions, such as the production of signaling molecules, antibiotics, other microbial metabolites, and even virulence

    Tuning Antibacterial Activity of Cyclodextrin-Attached Cationic Ammonium Surfactants by a Supramolecular Approach

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    Two β-cyclodextrin-attached cationic ammonium surfactants bearing a dodecyl chain (APDB) and a hexadecyl chain (APCB) were synthesized to reduce the cytotoxicity of cationic surfactants to mammalian cells and endow the surfactants with host–guest recognition sites, and three kinds of guest molecules were utilized to improve the antibacterial ability of APDB and APCB via host–guest interaction by regulating the electrostatic or hydrophobic interaction of APDB or APCB with bacteria. The guest molecules include AD-NH<sub>3</sub><sup>+</sup> carrying one positive charge, DB with a benzene ring group and a dodecyl chain, and single chain cationic ammonium surfactant DTAB or CTAB. Either AD-NH<sub>3</sub><sup>+</sup> or DB increases the killing efficacy of APCB against <i>S. aureus</i> at 50 μM from 59% to about 75%, while DTAB or CTAB improves the killing efficacy of APCB to more than 90%. In particular, only a very small amount CTAB can improve the antibacterial activity of APCB to a very high level, but keeps very low cytotoxicity. However, the mixtures of the guest molecules with APDB are devoid of any activity against <i>S. aureus</i>. This is mainly attributed to the fact that APCB and its mixtures with the guest molecules form 100–200 nm spherical aggregates, while the mixtures of APDB with the guest molecules cannot form aggregates at lower concentration. It is revealed that the three kinds of guest molecules trapped in the APCB spherical aggregates lead to diverse interaction modes of the APCB spherical aggregates with S. aureus, accounting for the different killing efficacy of the APCB/guest molecule mixtures. This supramolecular strategy provides an effective approach for the construction of highly efficient antibacterial agents with low cytotoxicity

    Direct Transformation of Amides into α‑Amino Phosphonates <i>via</i> a Reductive Phosphination Process

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    The first general method for the reductive phosphination of amides in one pot has been developed. The reactions described provide a novel access to α-amino phosphonates in good to excellent yields, cover a broad scope of substrates such as secondary and tertiary amides, and do not require a low temperature
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