Blanco Christian O, Fogg Deryn E
Center for Catalysis Research & Innovation and Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, Ontario, Canada K1N 6N5.
Department of Chemistry, University of Bergen, Allégaten 41, N-5007 Bergen, Norway.
ACS Catal. 2023 Jan 3;13(2):1097-1102. doi: 10.1021/acscatal.2c05573. eCollection 2023 Jan 20.
Water is ubiquitous in olefin metathesis, at levels ranging from contaminant to cosolvent. It is also non-benign. Water-promoted catalyst decomposition competes with metathesis, even for "robust" ruthenium catalysts. Metathesis is hence typically noncatalytic for demanding reactions in water-rich environments (e.g., chemical biology), a challenge as the Ru decomposition products promote unwanted reactions such as DNA degradation. To date, only the first step of the decomposition cascade is understood: catalyst aquation. Here we demonstrate that the aqua species dramatically accelerate both β-elimination of the metallacyclobutane intermediate and bimolecular decomposition of four-coordinate [RuCl(HO)(L)(=CHR)]Cl. Decomposition can be inhibited by blocking aquation and β-elimination.
水在烯烃复分解反应中普遍存在，其含量范围从污染物到助溶剂不等。而且它并非无害。水促进的催化剂分解与复分解反应相互竞争，即使对于“稳定”的钌催化剂也是如此。因此，对于在富水环境（如化学生物学）中要求苛刻的反应，复分解反应通常是非催化性的，这是一个挑战，因为钌分解产物会促进诸如DNA降解等不需要的反应。到目前为止，人们只了解分解级联反应的第一步：催化剂水合作用。在此我们证明，水合物种极大地加速了金属环丁烷中间体的β消除反应以及四配位[RuCl(HO)(L)(=CHR)]Cl的双分子分解反应。可以通过阻止水合作用和β消除反应来抑制分解。
