The Experts below are selected from a list of 48 Experts worldwide ranked by ideXlab platform

John F Hartwig - One of the best experts on this subject based on the ideXlab platform.

  • Palladium-Catalyzed Amination of Aryl Chlorides and Bromides with Ammonium Salts
    2016
    Co-Authors: Rebecca A Green, John F Hartwig
    Abstract:

    ABSTRACT: We report the palladium-catalyzed coupling of aryl halides with ammonia and gaseous amines as their ammonium salts. The coupling of aryl chlorides and ortho-substituted aryl bromides with ammonium sulfate forms anilines with higher selectivity for the Primary Arylamine over the diArylamine than couplings with ammonia in dioxane. The resting state for the reactions of aryl chlorides is different from the resting state for the reactions of aryl bromides, and this change in resting states is proposed to account for a difference in selectivities for reactions of the two haloarenes. The transition-metal-catalyzed amination of aryl electro-philes has become a useful method to construct Arylamines. However, the coupling of ammonia is less developed than the coupling of alkylamines, and several properties of ammonia make the coupling of this reagent more challenging than the coupling of alkylamines. Ammonia is a good σ-donor and binds more strongly to metals than do alkylamines, and this binding can lead to catalyst deactivation. In addition, the moderate basicity and low acidity of ammonia disfavor proton exchanges to or from thi

  • Palladium-Catalyzed Amination of Aryl Chlorides and Bromides with Ammonium Salts
    2015
    Co-Authors: Rebecca A. Green, John F Hartwig
    Abstract:

    We report the palladium-catalyzed coupling of aryl halides with ammonia and gaseous amines as their ammonium salts. The coupling of aryl chlorides and ortho-substituted aryl bromides with ammonium sulfate forms anilines with higher selectivity for the Primary Arylamine over the diArylamine than couplings with ammonia in dioxane. The resting state for the reactions of aryl chlorides is different from the resting state for the reactions of aryl bromides, and this change in resting states is proposed to account for a difference in selectivities for reactions of the two haloarenes

  • palladium catalyzed amination of aryl chlorides and bromides with ammonium salts
    Organic Letters, 2014
    Co-Authors: Rebecca A Green, John F Hartwig
    Abstract:

    We report the palladium-catalyzed coupling of aryl halides with ammonia and gaseous amines as their ammonium salts. The coupling of aryl chlorides and ortho-substituted aryl bromides with ammonium sulfate forms anilines with higher selectivity for the Primary Arylamine over the diArylamine than couplings with ammonia in dioxane. The resting state for the reactions of aryl chlorides is different from the resting state for the reactions of aryl bromides, and this change in resting states is proposed to account for a difference in selectivities for reactions of the two haloarenes.

  • palladium catalyzed coupling of ammonia and lithium amide with aryl halides
    Journal of the American Chemical Society, 2006
    Co-Authors: Qilong Shen, John F Hartwig
    Abstract:

    A mild, palladium-catalyzed coupling of aryl halides with ammonia or lithium amide to form Primary Arylamines as the major product is described. These reactions occurred with excellent selectivity for formation of the Primary Arylamine over formation of the diArylamine (9.5:1 to over 50:1 ratios of Arylamine to diArylamine). In addition, the first organopalladium complex with a terminal −NH2 ligand has been isolated. This complex reductively eliminates to form Arylamines.

Rebecca A Green - One of the best experts on this subject based on the ideXlab platform.

  • Palladium-Catalyzed Amination of Aryl Chlorides and Bromides with Ammonium Salts
    2016
    Co-Authors: Rebecca A Green, John F Hartwig
    Abstract:

    ABSTRACT: We report the palladium-catalyzed coupling of aryl halides with ammonia and gaseous amines as their ammonium salts. The coupling of aryl chlorides and ortho-substituted aryl bromides with ammonium sulfate forms anilines with higher selectivity for the Primary Arylamine over the diArylamine than couplings with ammonia in dioxane. The resting state for the reactions of aryl chlorides is different from the resting state for the reactions of aryl bromides, and this change in resting states is proposed to account for a difference in selectivities for reactions of the two haloarenes. The transition-metal-catalyzed amination of aryl electro-philes has become a useful method to construct Arylamines. However, the coupling of ammonia is less developed than the coupling of alkylamines, and several properties of ammonia make the coupling of this reagent more challenging than the coupling of alkylamines. Ammonia is a good σ-donor and binds more strongly to metals than do alkylamines, and this binding can lead to catalyst deactivation. In addition, the moderate basicity and low acidity of ammonia disfavor proton exchanges to or from thi

  • palladium catalyzed amination of aryl chlorides and bromides with ammonium salts
    Organic Letters, 2014
    Co-Authors: Rebecca A Green, John F Hartwig
    Abstract:

    We report the palladium-catalyzed coupling of aryl halides with ammonia and gaseous amines as their ammonium salts. The coupling of aryl chlorides and ortho-substituted aryl bromides with ammonium sulfate forms anilines with higher selectivity for the Primary Arylamine over the diArylamine than couplings with ammonia in dioxane. The resting state for the reactions of aryl chlorides is different from the resting state for the reactions of aryl bromides, and this change in resting states is proposed to account for a difference in selectivities for reactions of the two haloarenes.

Xuelong Sun - One of the best experts on this subject based on the ideXlab platform.

  • Primary Arylamine based tyrosine targeted protein modification
    RSC Advances, 2014
    Co-Authors: Lin Wang, Valentinas Gruzdys, Nan Pang, Fanhao Meng, Xuelong Sun
    Abstract:

    Tyrosine-targeted modification is of great interest in the site-specific protein modification applications. Aniline derivatives are attractive molecules for tyrosine-targeted protein modifications through either diazonium coupling or three-component Mannich type reactions. In this report, with BSA as a model protein, Primary Arylamines were demonstrated to incorporate bioorthogonal azide functionality for further site-specific protein modification via click chemistry, glycans for glyco-engineering, and PEG chains for PEGylation to the protein via tyrosine-targeted modification. The successful Primary Arylamine-based BSA modifications were confirmed by SDS-PAGE, western blot, and MALDI-TOF mass spectrometry. In comparison, three-component Mannich type reaction affords much higher reaction yields than diazonium coupling reaction in all modifications. Further, this study confirmed the importance of the electron withdrawing substituent on the para position of the phenyl ring for the tyrosine-targeted diazonium coupling reaction.

Qilong Shen - One of the best experts on this subject based on the ideXlab platform.

  • palladium catalyzed coupling of ammonia and lithium amide with aryl halides
    Journal of the American Chemical Society, 2006
    Co-Authors: Qilong Shen, John F Hartwig
    Abstract:

    A mild, palladium-catalyzed coupling of aryl halides with ammonia or lithium amide to form Primary Arylamines as the major product is described. These reactions occurred with excellent selectivity for formation of the Primary Arylamine over formation of the diArylamine (9.5:1 to over 50:1 ratios of Arylamine to diArylamine). In addition, the first organopalladium complex with a terminal −NH2 ligand has been isolated. This complex reductively eliminates to form Arylamines.

Lin Wang - One of the best experts on this subject based on the ideXlab platform.

  • Primary Arylamine based tyrosine targeted protein modification
    RSC Advances, 2014
    Co-Authors: Lin Wang, Valentinas Gruzdys, Nan Pang, Fanhao Meng, Xuelong Sun
    Abstract:

    Tyrosine-targeted modification is of great interest in the site-specific protein modification applications. Aniline derivatives are attractive molecules for tyrosine-targeted protein modifications through either diazonium coupling or three-component Mannich type reactions. In this report, with BSA as a model protein, Primary Arylamines were demonstrated to incorporate bioorthogonal azide functionality for further site-specific protein modification via click chemistry, glycans for glyco-engineering, and PEG chains for PEGylation to the protein via tyrosine-targeted modification. The successful Primary Arylamine-based BSA modifications were confirmed by SDS-PAGE, western blot, and MALDI-TOF mass spectrometry. In comparison, three-component Mannich type reaction affords much higher reaction yields than diazonium coupling reaction in all modifications. Further, this study confirmed the importance of the electron withdrawing substituent on the para position of the phenyl ring for the tyrosine-targeted diazonium coupling reaction.