Comparison of Monophosphine and Bisphosphine Precatalysts for Ni-Catalyzed Suzuki–Miyaura Cross-Coupling: Understanding the Role of the Ligation State in Catalysis,ACS Catalysis

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Comparison of Monophosphine and Bisphosphine Precatalysts for Ni-Catalyzed Suzuki–Miyaura Cross-Coupling: Understanding the Role of the Ligation State in Catalysis
ACS Catalysis ( IF 11.3 ) Pub Date : 2023-05-30 , DOI: 10.1021/acscatal.3c01331
Julia E Borowski ₁ , Samuel H Newman-Stonebraker _{1,

2} , Abigail G Doyle ₂

Affiliation

Practical advances in Ni-catalyzed Suzuki–Miyaura cross-coupling (SMC) have been limited by a lack of mechanistic understanding of phosphine ligand effects. While bisphosphines are commonly used in these methodologies, we have observed instances where monophosphines can provide comparable or higher levels of reactivity. Seeking to understand the role of ligation state in catalysis, we performed a head-to-head comparison study of C(sp²)–C(sp²) Ni SMCs catalyzed by mono- and bisphosphine precatalysts using six distinct substrate pairings. Significant variation in optimal precatalyst was observed, with the monophosphine precatalyst tending to outperform the bisphosphines with electronically deactivated and sterically hindered substrates. Mechanistic experiments revealed a role for monoligated (P₁Ni) species in accelerating the fundamental organometallic steps of the catalytic cycle while highlighting the need for bisligated (P₂Ni) species to avoid off-cycle reactivity and catalyst poisoning by heterocyclic motifs. These findings provide guidelines for ligand selection against challenging substrates and future ligand design tailored to the mechanistic demands of Ni-catalyzed SMCs.

中文翻译：

Ni 催化 Suzuki-Miyaura 交叉偶联的单膦和双膦预催化剂的比较：了解连接态在催化中的作用

由于缺乏对膦配体效应的机制理解，镍催化铃木-宫浦交叉偶联（SMC）的实际进展受到限制。虽然双膦常用于这些方法，但我们观察到单膦可以提供相当或更高水平的反应性。为了了解连接状态在催化中的作用，我们使用六种不同的底物配对对单膦和双膦预催化剂催化的 C(sp ² )–C(sp ² ) Ni SMC 进行了头对头比较研究。观察到最佳预催化剂的显着变化，单膦预催化剂往往优于具有电子失活和空间位阻底物的双膦。机理实验揭示了单配位 (P ₁ Ni) 物质在加速催化循环的基本有机金属步骤中的作用，同时强调需要双配位 (P ₂ Ni) 物质以避免杂环基序的脱循环反应性和催化剂中毒。这些发现为针对具有挑战性的底物的配体选择以及未来根据镍催化SMC的机械需求量身定制的配体设计提供了指导。

更新日期：2023-05-30

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