Newman-Stonebraker Samuel H, Raab T Judah, Doyle Abigail G
Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA.
Department of Chemistry and Biochemistry, University of California Los Angeles, Los Angeles, California 90095, USA.
Organometallics. 2023 Dec 25;42(24):3438-3441. doi: 10.1021/acs.organomet.3c00450. Epub 2023 Dec 13.
Cross-coupling catalysts are prone to unproductive side reactivity that can limit their practical use in synthetic chemistry. A detailed understanding of these pathways and the conditions that enable them is important for reaction optimization and rational catalyst design. In this work, we report the off-cycle reactivity of a monoligated, CyJohnPhos-bound Ni complex following product-forming reductive elimination. In the absence of substrate, free phosphine ligand, or π-accepting additives, dimerization of (CyJohnPhos)Ni occurs, followed by C-P bond activation of the ligand to form a phosphido-bridged Ni/Ni dimer; both the Ni/Ni and Ni/Ni dimers were structurally characterized. Monomeric (CyJohnPhos)Ni must be intercepted by substrate or free ligand to prevent irreversible dimerization and catalyst deactivation.
交叉偶联催化剂易于发生非生产性的副反应，这可能会限制它们在合成化学中的实际应用。详细了解这些反应途径以及促成这些反应的条件对于反应优化和合理的催化剂设计至关重要。在这项工作中，我们报道了在发生生成产物的还原消除反应后，单配位、与CyJohnPhos结合的Ni络合物的循环外反应活性。在没有底物、游离膦配体或π-受体添加剂的情况下，(CyJohnPhos)Ni会发生二聚化，随后配体的C-P键活化形成磷桥连的Ni/Ni二聚体；对Ni/Ni和Ni/Ni二聚体都进行了结构表征。单体(CyJohnPhos)Ni必须被底物或游离配体拦截，以防止不可逆的二聚化和催化剂失活。
