Synthesis and Application of Air-Stable Secondary Phosphine Oxide, Oxime, and Amine-Phosphine Palladium(II) Complexes in Transfer Hydrogenation and Cross-Coupling Reactions
type: CreativeWork
description: Catalysis plays an important role in industry as over 90% of chemical processes involve catalysts in at least one step. Historically, heterogeneous catalysis has been more commonly employed in industry as these systems tend to be more economically friendly and environmentally benign. However, improved procedures for homogeneous catalysis using organocatalysts and organometallic compounds has generated increased interest in homogeneous systems. Organometallic compounds offer higher specific activities and selectivity in comparison to traditional heterogeneous systems. These qualities make homogeneous catalysis particularly attractive for the production of fine chemicals, pharmaceuticals, and natural products. Ligand design is critical for the development of homogeneous catalysts. For late-transition-metal-catalyzed cross-coupling reactions that rely on C-X or C-H oxidative addition, strongly electron-donating and sterically demanding ligands afford the most efficient systems. Several privileged classes of ligands have been identified and employed in palladium-catalyzed reactions. These systems are believed to promote their respective reactions through a monoligated palladium(0) species. Our work focused on the development of precatalysts with an established 1:1 L:Pd ratio. Specifically, we were interested in the synthesis of palladium(II) precatalysts with the general formula (R3P)Pd(amine)Cl2, using di-tert-butylneopentylphosphine and trineopentylphosphine. Under optimized conditions, the precatalysts were effective for the Buchwald-Hartwig amination of aryl bromides and aryl chlorides. We discovered that the identity of the amine ligand significantly impacts catalyst efficiency with linear primary alkyl amines providing the most active catalysts. A comparison study between the air-stable precatalysts and in situ generated catalysts showed improved activity for the precatalysts. Typically, the aforementioned privileged classes of ligands behave as spectators during …
abstract: Catalysis plays an important role in industry as over 90% of chemical processes involve catalysts in at least one step. Historically, heterogeneous catalysis has been more commonly employed in industry as these systems tend to be more economically friendly and environmentally benign. However, improved procedures for homogeneous catalysis using organocatalysts and organometallic compounds has generated increased interest in homogeneous systems. Organometallic compounds offer higher specific activities and selectivity in comparison to traditional heterogeneous systems. These qualities make homogeneous catalysis particularly attractive for the production of fine chemicals, pharmaceuticals, and natural products. Ligand design is critical for the development of homogeneous catalysts. For late-transition-metal-catalyzed cross-coupling reactions that rely on C-X or C-H oxidative addition, strongly electron-donating and sterically demanding ligands afford the most efficient systems. Several privileged classes of ligands have been identified and employed in palladium-catalyzed reactions. These systems are believed to promote their respective reactions through a monoligated palladium(0) species. Our work focused on the development of precatalysts with an established 1:1 L:Pd ratio. Specifically, we were interested in the synthesis of palladium(II) precatalysts with the general formula (R3P)Pd(amine)Cl2, using di-tert-butylneopentylphosphine and trineopentylphosphine. Under optimized conditions, the precatalysts were effective for the Buchwald-Hartwig amination of aryl bromides and aryl chlorides. We discovered that the identity of the amine ligand significantly impacts catalyst efficiency with linear primary alkyl amines providing the most active catalysts. A comparison study between the air-stable precatalysts and in situ generated catalysts showed improved activity for the precatalysts. Typically, the aforementioned privileged classes of ligands behave as spectators during …
author: Pierce, Jordan Kay
language: en_US
language: English
date published: 2022
date modified: 2026-07-27T18:44:27Z
provider: University of Alabama
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Alabama Libraries