8 research outputs found

    Selective Hydrogenation of Ruthenium Acylphosphine Complexes

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    Hydrogenation of a benzene ruthenium chloride dimer in the presence of novel acyl­phosphine (phosphomide) ligands resulted in the formation of corresponding ruthenium­(II)–benzyl phosphine complexes. Here, selective reduction of the carbonyl group to a methylene unit takes place with molecular hydrogen under mild conditions in good yield. This approach provides an alternative synthesis of ruthenium phosphine complexes of benzyl and heterobenzyl phosphine ligands

    Synthesis of <i>N</i>‑Lauroyl Sarcosine by Amidocarbonylation: Comparing Homogeneous and Heterogeneous Palladium Catalysts

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    An improved system for the synthesis of <i>N</i>-acyl amino acids via Pd-catalyzed amidocarbonylation is reported. Utilizing inexpensive Pd black gives the industrially important surfactant <i>N</i>-lauroyl sarcosine in excellent yields (95%) on a multi-gram scale. Advantages of the new system include reusability, decreased process temperature, and, importantly, drastically decreased co-catalyst loading

    General and Regioselective Synthesis of Pyrroles via Ruthenium-Catalyzed Multicomponent Reactions

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    A general and highly regioselective synthesis of pyrroles via ruthenium-catalyzed three-component reactions has been developed. A variety of ketones including less reactive aryl and alkyl substrates were efficiently converted in combination with different type of amines and vicinal diols into various substituted pyrroles in reasonable to excellent isolated yields. Additionally, α-functionalized ketones gave synthetically interesting amido-, alkoxy-, aryloxy-, and phosphate-substituted pyrroles in a straightforward manner. The synthetic protocol proceeds in the presence of a commercially available ruthenium catalyst system and catalytic amount of base. It proceeds with high atom-efficiency and shows a broad substrate scope and functional group tolerance, making it a highly practical approach for preparation of various pyrrole derivatives

    Selective Hydrogenation of Ruthenium Acylphosphine Complexes

    No full text
    Hydrogenation of a benzene ruthenium chloride dimer in the presence of novel acyl­phosphine (phosphomide) ligands resulted in the formation of corresponding ruthenium­(II)–benzyl phosphine complexes. Here, selective reduction of the carbonyl group to a methylene unit takes place with molecular hydrogen under mild conditions in good yield. This approach provides an alternative synthesis of ruthenium phosphine complexes of benzyl and heterobenzyl phosphine ligands

    Selective Palladium-Catalyzed Carbonylation of Alkynes: An Atom-Economic Synthesis of 1,4-Dicarboxylic Acid Diesters

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    A class of novel diphosphine ligands bearing pyridine substituents was designed and synthesized for the first time. The resulting palladium complexes of <b>L1</b> allow for chemo- and regioselective dialkoxycarbonylation of various aromatic and aliphatic alkynes affording a wide range of 1,4-dicarboxylic acid diesters in high yields and selectivities. Kinetic studies suggest the generation of 1,4-dicarboxylic acid diesters via cascade hydroesterification of the corresponding alkynes. Based on these investigations, the chemo- and regioselectivities of alkyne carbonylations can be controlled as shown by switching the ligand from <b>L1</b> to <b>L3</b> or <b>L9</b> to give α,β-unsaturated esters

    Palladium-Catalyzed Selective Generation of CO from Formic Acid for Carbonylation of Alkenes

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    A general and selective palladium-catalyzed alkoxycarbonylation of all kinds of alkenes with formic acid (HCOOH, FA) is described. Terminal, di-, tri-, and tetra-substituted including functionalized olefins are converted into linear esters with high yields and regioselectivity. Key-to-success is the use of specific palladium catalysts containing ligands with built-in base, e.g., <b>L5</b>. Comparison experiments demonstrate that the active catalyst system not only facilitates isomerization and carbonylation of alkenes but also promotes the selective decomposition of HCOOH to CO under mild conditions

    Ruthenium-Catalyzed Selective α,β-Deuteration of Bioactive Amines

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    A novel and convenient protocol for the catalytic hydrogen–deuterium exchange of biologically active tertiary amines utilizing the borrowing hydrogen methodology has been developed. In the presence of the readily available Shvo catalyst, excellent chemoselectivity toward α- and β-protons with respect to the nitrogen atom as well as high degree of deuterium incorporation and functional group tolerance is achieved. This allowed for the deuteration of complex pharmaceutically interesting substrates, including examples for actual marketed drug compounds. Notably, this method constitutes a powerful tool for the generation of valuable internal standard materials for LC–MS/MS analyses highly demanded for various life-science applications

    Combining Isocyanides with Carbon Dioxide in Palladium-Catalyzed Heterocycle Synthesis: <i>N</i>3‑Substituted Quinazoline-2,4(1<i>H</i>,3<i>H</i>)‑diones via a Three-Component Reaction

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    We report a Pd-catalyzed three-component reaction of 2-bromoanilines, carbon dioxide, and isocyanides. The combination of these two readily available C<sub>1</sub>-reactants, featuring a huge difference in kinetic and thermodynamic stability, is hitherto unprecedented in transition-metal catalysis. With this one-pot three-component reaction, <i><i>N</i></i>3-substituted quinazoline-2,4­(1<i>H</i>,3<i>H</i>)-diones are obtained in moderate to high yields in a completely regio- and chemoselective manner. Our approach easily allows variation of the arene and <i>N</i>3-substitution pattern of the desired heterocycle. The formal synthesis of different APIs illustrates its practical applicability. In addition, the methodology also allows for a convenient and selective <sup>13</sup>C-labeling through the use of <sup>13</sup>CO<sub>2</sub>. This is illustrated for [2-<sup>13</sup>C]-2,4-dichloro-6,7-dimethoxyquinazoline synthesis, a key intermediate for several APIs
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