Affiliation:
1. Beijing National Laboratory for Molecular Sciences (BNLMS), State Key Laboratory of Rare Earth Materials Chemistry and Applications & Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, College of Chemistry and Molecular Engineering Peking University Beijing 100871 P. R. China
Abstract
AbstractAzametallacyclopentadienes are an important class of metallacycles as the key intermediates in metal‐promoted or catalyzed carbon‐carbon coupling reaction of nitriles and alkynes. Rare‐earth azametallacyclopentadienes have shown various reactivity toward nitriles, depending on the substituents of nitriles. The reaction of azalutetacyclopentadienes toward 2‐methylbenzonitriles has been investigated in this work, which selectively affords the fused 7‐5‐6‐membered azalutetacycles as products. Computational studies reveal that the reaction of azalutetacyclopentadienes toward 2‐methylbenzonitriles selectively initiates with the remote activation of the benzylic C−H bond by the Lu−N bond, followed by the intramolecular nucleophilic attack from the deprotonated benzylic carbon to form a C−C bond. Subsequently, the high ring strain promoted the generation of the uncoordinated carbanion dissociated from the lutetium center, which then undergoes intramolecular nucleophilic attack toward C=N triple bond to give the final product containing fused 7‐5‐6‐membered azalutetacycle. This work not only achieves highly selective three‐step cascade reaction to form a unique class of rare‐earth metallacycle, but also provides a new idea for the transformation of unsaturated substrates with C−H bonds that can be activated.