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Amide

The Experts below are selected from a list of 309 Experts worldwide ranked by ideXlab platform

Michal Szostak – 1st expert on this subject based on the ideXlab platform

  • buchwald hartwig cross coupling of Amides transamidation by selective n c o cleavage mediated by air and moisture stable pd nhc allyl cl precatalysts catalyst evaluation and mechanism
    Catalysis Science & Technology, 2020
    Co-Authors: Guangchen Li, Tongliang Zhou, Albert Poater, Luigi Cavallo, Steven P. Nolan, Michal Szostak

    Abstract:

    The Pd–NHC-catalyzed acyl-type Buchwald–Hartwig cross-coupling of Amides by N–C(O) cleavage (transamidation) provides a valuable alternative to the classical methods for Amide synthesis. Herein, we report a combined experimental and computational study of the Buchwald–Hartwig cross-coupling of Amides using well-defined, air- and moisture-stable [Pd(NHC)(allyl)Cl] precatalysts. Most crucially, we present a comprehensive evaluation of a series of distinct Pd(II)–NHC precatalysts featuring different NHC scaffolds and throw-away ligands for the synthesis of functionalized Amides that are not compatible with stoichiometric transition-metal-free transamidation methods. Furthermore, we present evaluation of the catalytic cycle by DFT methods for a series of different Pd(II)–NHC precatalysts. The viability of accessing NHC-supported acyl-palladium(II) amido complexes will have implications for the design and development of cross-coupling methods involving stable Amide electrophiles.

  • twisted n acyl hydantoins rotationally inverted urea imides of relevance in n c o cross coupling
    Journal of Organic Chemistry, 2018
    Co-Authors: Roman Szostak, Roger A. Lalancette, Michal Szostak

    Abstract:

    We report a combined structural and computational study on the properties of twisted acyclic hydantoins. These compounds feature cyclic urea-imide moiety that is widely found in bioactive compounds and is structurally related to the classic bridged hydantoins proposed by Smissman more than 50 years ago. We demonstrate that C to N-substitution of the imide moiety in the succinimide ring to give hydantoin results in one of the most distorted acyclic Amide bonds reported to date. The energetic properties of twisted acyclic hydantoins with respect to structures, resonance energies, barriers to rotation, and proton affinities are discussed. The energetic and structural properties of twisted acyclic hydantoins described provide a benchmark to facilitate the development of twisted Amides based on the biorelevant cyclic urea-imide scaffold.

  • Structures of Highly Twisted Amides Relevant to Amide N−C Cross‐Coupling: Evidence for Ground‐State Amide Destabilization
    Chemistry: A European Journal, 2016
    Co-Authors: Vittorio Pace, Roman Szostak, Roger A. Lalancette, Guangrong Meng, Wolfgang Holzer, Michal Szostak

    Abstract:

    Herein, we show that acyclic Amides that have recently enabled a series of elusive transition-metal-catalyzed N−C activation/cross-coupling reactions are highly twisted around the N−C(O) axis by a new destabilization mechanism of the Amide bond. A unique effect of the N-glutarimide substituent, leading to uniformly high twist (ca. 90°) irrespective of the steric effect at the carbon side of the Amide bond has been found. This represents the first example of a twisted Amide that does not bear significant steric hindrance at the α-carbon atom. The 15N NMR data show linear correlations between electron density at nitrogen and Amide bond twist. This study strongly supports the concept of Amide bond ground-state twist as a blueprint for activation of Amides toward N−C bond cleavage. The new mechanism offers considerable opportunities for organic synthesis and biological processes involving non-planar Amide bonds.

Subhash Chandra Ghosh – 2nd expert on this subject based on the ideXlab platform

  • copper catalyzed oxidative amidation of aldehydes with amine salts synthesis of primary secondary and tertiary Amides
    Journal of Organic Chemistry, 2012
    Co-Authors: Subhash Chandra Ghosh, Joyce S Y Ngiam, Abdul Majeed Seayad, Dang Thanh Tuan, Christina L. L. Chai, Anqi Chen

    Abstract:

    A practical method for the amidation of aldehydes with economic ammonium chloride or amine hydrochloride salts has been developed for the synthesis of a wide variety of Amides by using inexpensive copper sulfate or copper(I) oxide as a catalyst and aqueous tert-butyl hydroperoxide as an oxidant. This amidation reaction is operationally straightforward and provides primary, secondary, and tertiary Amides in good to excellent yields for most cases utilizing inexpensive and readily available reagents under mild conditions. In situ formation of amine salts from free amines extends the substrate scope of the reaction. Chiral Amides are also synthesized from their corresponding chiral amines without detectable racemization. The practicality of this Amide formation reaction has been demonstrated in an efficient synthesis of the antiarrhythmic drug N-acetylprocainAmide.

  • iron catalyzed efficient synthesis of Amides from aldehydes and amine hydrochloride salts
    Advanced Synthesis & Catalysis, 2012
    Co-Authors: Subhash Chandra Ghosh, Joyce S Y Ngiam, Abdul Majeed Seayad, Christina L. L. Chai, Tuan Thanh Dang, Anqi Chen

    Abstract:

    A practical and efficient method for the synthesis of Amides has been developed by iron-cat- alysed oxidative amidation of aldehydes with amine hydrochloride salts. A wide range of Amides have been obtained in good to excellent yields under mild conditions. The application of this novel Amide formation reaction to the synthesis of pharmaceuti- cal compounds has been successfully demonstrated.

  • direct Amide synthesis from either alcohols or aldehydes with amines activity of ru ii hydride and ru 0 complexes
    Journal of Organic Chemistry, 2010
    Co-Authors: Senthilkumar Muthaiah, Subhash Chandra Ghosh, Cheng Chen, Jian Zhang, Soon Hyeok Hong

    Abstract:

    An in situ generated catalyst from readily available RuH2(PPh3)4, an N-heterocyclic carbene (NHC) precursor, NaH, and acetonitrile was developed. The catalyst showed high activity for the Amide synthesis directly from either alcohols or aldehydes with amines. When a mixture of an alcohol and an aldehyde was reacted with an amine, both of the corresponding Amides were obtained with good yields. Homogeneous Ru(0) complexes such as (η4-1,5-cyclooctadiene)(η6-1,3,5-cyclooctatriene)ruthenium [Ru(cod)(cot)] and Ru3(CO)12 were also active in the amidation of an alcohol or an aldehyde with the help of an in situ generated NHC ligand.

Anqi Chen – 3rd expert on this subject based on the ideXlab platform

  • copper catalyzed oxidative amidation of aldehydes with amine salts synthesis of primary secondary and tertiary Amides
    Journal of Organic Chemistry, 2012
    Co-Authors: Subhash Chandra Ghosh, Joyce S Y Ngiam, Abdul Majeed Seayad, Dang Thanh Tuan, Christina L. L. Chai, Anqi Chen

    Abstract:

    A practical method for the amidation of aldehydes with economic ammonium chloride or amine hydrochloride salts has been developed for the synthesis of a wide variety of Amides by using inexpensive copper sulfate or copper(I) oxide as a catalyst and aqueous tert-butyl hydroperoxide as an oxidant. This amidation reaction is operationally straightforward and provides primary, secondary, and tertiary Amides in good to excellent yields for most cases utilizing inexpensive and readily available reagents under mild conditions. In situ formation of amine salts from free amines extends the substrate scope of the reaction. Chiral Amides are also synthesized from their corresponding chiral amines without detectable racemization. The practicality of this Amide formation reaction has been demonstrated in an efficient synthesis of the antiarrhythmic drug N-acetylprocainAmide.

  • iron catalyzed efficient synthesis of Amides from aldehydes and amine hydrochloride salts
    Advanced Synthesis & Catalysis, 2012
    Co-Authors: Subhash Chandra Ghosh, Joyce S Y Ngiam, Abdul Majeed Seayad, Christina L. L. Chai, Tuan Thanh Dang, Anqi Chen

    Abstract:

    A practical and efficient method for the synthesis of Amides has been developed by iron-cat- alysed oxidative amidation of aldehydes with amine hydrochloride salts. A wide range of Amides have been obtained in good to excellent yields under mild conditions. The application of this novel Amide formation reaction to the synthesis of pharmaceuti- cal compounds has been successfully demonstrated.