Progress of Azametallacyclopentadienes in the New Century
Ze-Jie Lv, Wei Liu, and Wen-Xiong Zhang*
Chem. Eur. J. 2023, 29, e202204079. (Invited Concept) https://doi.org/10.1002/chem.202204079.
As the key intermediates in metal promoted/catalyzed C‒C bond coupling reactions of nitriles and alkynes, azametallacyclopentadienes, M(N=CR1‒CR2=CR3), are an important class of azametallacycles. Although the first authentic azametallacyclopentadienes were documented in 1986, their chemistry towards solid-state structures, intrinsic reactivity and synthetic application was rarely investigated for a long time. At the beginning of this century, seminal works about the applications of azametallacyclopentadienes in the synthesis of heterocycles, including multi-substituted pyridines, isoquinolines, furans and pyrroles were reported. Subsequently, a series of new complexes with this motif, namely the group 4, aluminum, actinide and rare-earth azametallacyclopentadienes were isolated and structurally characterized. Among them, the rare-earth metallacyclopentadiene expresses high reactivity towards unsaturated molecules, such as nitriles, isocyanides and Mo(CO)6 to provide novel fused metallacycles. In this concept, we summarized the advances towards the preparation, reactivity and synthetic application of azametallacyclopentadienes in past twenty years.
