AbstractInvestigations into C−H amidation reactions catalysed by cationic half‐sandwich d6 metal complexes revealed that the indenyl‐derived catalyst [Ind*RhCl2]2 significantly accelerated the directed ortho C−H amidation of benzoyl silanes using 1,4,2‐dioxazol‐5‐ones. Ring slippage involving a haptotropic η5 to η3 rearrangement of the indenyl complex proposedly enables ligand substitution at the metal centre to proceed via associative, rather than dissociative pathways, leading to significant rate and yield enhancements. Intriguingly, this phenomenon appears specific for C−H amidation reactions involving weakly coordinating carbonyl‐based directing groups with no acceleration observed for the corresponding reactions involving strongly coordinating nitrogen‐based directing groups.
摘要 对阳离子半夹心 d6 金属配合物催化的 C-H 酰胺化反应的研究发现,茚基催化剂 [Ind*RhCl2]2 能显著加速使用 1,4,2-二恶唑-5-酮的苯甲酰硅烷的定向正交 C-H 酰胺化反应。茚基复合物的η5到η3重排的触变滑环现象使金属中心的配体置换能够通过缔合途径而不是离解途径进行,从而显著提高了速率和产率。耐人寻味的是,这种现象似乎是涉及弱配位羰基导向基团的 C-H amidation 反应所特有的,而涉及强配位氮基导向基团的相应反应则没有观察到加速现象。