8 research outputs found

    Palladium-Catalyzed Amination of Unprotected Five-Membered Heterocyclic Bromides

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    An efficient method for the palladium-catalyzed amination of unprotected bromoimidazoles and bromopyrazoles is presented. The transformation is facilitated by the use of our newly developed Pd precatalyst based on the bulky biarylphosphine ligand <i>t</i>BuBrettPhos (<b>L4</b>). The mild reaction conditions employed allow for the preparation of a broad scope of aminoimidazoles and aminopyrazoles in moderate to excellent yields

    Palladium-Catalyzed Arylation of Cyclopropanes via Directing Group-Mediated C(sp<sup>3</sup>)–H Bond Activation To Construct Quaternary Carbon Centers: Synthesis of <i>cis</i>- and <i>trans</i>-1,1,2-Trisubstituted Chiral Cyclopropanes

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    Pd(II)-catalyzed tertiary C(sp<sup>3</sup>)–H arylation of cyclopropanes via directing group-mediated C–H activation for the construction of a chiral quaternary carbon center on cyclopropanes using aryl iodides as a coupling partner is reported. The arylation had a wide substrate scope and good functional group tolerance, including heteroaryl iodides, to provide various chiral arylcyclopropanes with the <i>cis</i>- and <i>trans</i>-1,1,2-trisubstituted structures

    Total Synthesis of (+)-Goniodenin

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    Goniodenin is a lipophilic polyketide originating from plant sources and which possesses a potent cytotoxic activity against cancer cell lines. The first total synthesis of (+)-goniodenin has been achieved in 23 steps from (<i>R</i>)-glycidol. The synthetic sequence featured a cross metathesis for the formation of the C<sub>8</sub>–C<sub>9</sub> bond and installation of the terminal γ-butenolactone ring unit by the alkylation of α-phenylthio-γ-butyrolactone with the corresponding C<sub>3</sub>-<i>O</i>-triflate. The stereogenic center at C<sub>18</sub> carbon was created by Hiyama–Fujita reduction of the corresponding ketone with high diastereoselectivity

    Entry to Chiral 1,1,2,3-Tetrasubstituted Arylcyclopropanes by Pd(II)-Catalyzed Arylation via Directing Group-Mediated C(sp<sup>3</sup>)‑H Activation

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    Here we report the construction of highly functionalized chiral 1,1,2,3-tetrasubstituted arylcyclopropanes of medicinal chemical importance using Pd­(II)-catalyzed arylation via directing group-mediated C­(sp<sup>3</sup>)-H activation. The key aspect for the effective arylation was control of the substrate conformation based on the characteristic steric and stereoelectronic features of cyclopropane by manipulating the protecting group at the hydroxyl. The arylation with good functional group tolerance is pivotal as the first entry to chiral 1,1,2,3-tetrasubstituted arylcyclopropanes with wide variety of aryl groups, including heteroaryl groups

    Construction of Iterative Tetrahydrofuran Ring Units and Total Synthesis of (+)-Goniocin

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    Cytotoxic acetogenin (+)-goniocin has been synthesized in 17 steps from (<i>R</i>)-<i>O</i>-tritylglycidol. The core structure of the contiguous C<sub>22</sub>–C<sub>10</sub> <i>threo-trans-threo-trans-threo-trans-</i>tris-tetrahydrofuran (THF) ring involving an iterative THF-ring unit was synthesized. An iterative THF ring unit was constructed from an alkenyl-substituted THF ring in four steps including a Pd­(II)-catalyzed ring-closing reaction and cross-metathesis. This method is general and allows the preparation of both <i>trans-threo-trans-</i> and <i>trans-threo-cis-</i>THF ring units flexibly

    Ligand-Free Suzuki–Miyaura Coupling with Sulfur-Modified Gold-Supported Palladium in the Synthesis of a Conformationally-Restricted Cyclopropane Compound Library with Three-Dimensional Diversity

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    A conformationally restricted privileged structure library with stereochemical diversity for a “fragment growth” methodology comprising 90 compounds was designed and systematically and efficiently synthesized using <u>s</u>ulfur-modified <u>A</u>u-supported <u>Pd</u> (SAPd)-catalyzed ligand-free Suzuki–Miyaura coupling of vinyl iodide promoted by microwave and subsequent amidation in liquid-phase combinatorial chemistry as key reactions. Evaluation of the compounds with a 20-kinase panel indicated the usefulness of this “fragment growth” methodology for finding hit library compounds for fragment-based drug discovery

    Preparation of Chiral Bromomethylenecyclopropane and Its Use in Suzuki–Miyaura Coupling: Synthesis of the Arylmethyl‑(<i>Z</i>)‑cyclopropane Structure Core

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    A preparative method for an optically active bromomethylenecyclopropane unit and its practical conversion to (<i>Z</i>)-cyclopropane-containing chiral compounds via Suzuki–Miyaura coupling were established

    Palladium-Nanoparticle-Catalyzed 1,7-Palladium Migration Involving C–H Activation, Followed by Intramolecular Amination: Regioselective Synthesis of <i>N</i>1‑Arylbenzotriazoles and an Evaluation of Their Inhibitory Activity toward Indoleamine 2,3-Dioxygenase

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    A sulfur-modified gold-supported palladium material (SAPd) has been developed bearing palladium nanoparticles on its surface. Herein, we report for the first time the use of SAPd to affect a Pd-nanoparticle-catalyzed 1,7-Pd migration reaction for the synthesis of benzo­triazoles via C–H bond activation. The resulting benzo­triazoles were evaluated in terms of their inhibitory activity toward indole­amine 2,3-dioxygenase
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