Highly Efficient Conversion of Propargylic Amines and CO<sub>2</sub> Catalyzed by Noble‐Metal‐Free [Zn<sub>116</sub>] Nanocages
Chun‐Shuai Cao, Shumei Xia, Zhenjun Song, Hang Xu, Ying Shi, Liang‐Nian He, Peng Cheng, Bin Zhao
Abstract
Abstract The reaction of propargylic amines and CO 2 can provide high‐value‐added chemical products. However, most of catalysts in such reactions employ noble metals to obtain high yield, and it is important to seek eco‐friendly noble‐metal‐free MOFs catalysts. Here, a giant and lantern‐like [Zn 116 ] nanocage in zinc‐tetrazole 3D framework [Zn 22 (Trz) 8 (OH) 12 (H 2 O) 9 ⋅8 H 2 O] n Trz=(C 4 N 12 O) 4− ( 1 ) was obtained and structurally characterized. It consists of six [Zn 14 O 21 ] clusters and eight [Zn 4 O 4 ] clusters. To our knowledge, this is the highest‐nuclearity nanocages constructed by Zn‐clusters as building blocks to date. Importantly, catalytic investigations reveal that 1 can efficiently catalyze the cycloaddition of propargylic amines with CO 2 , exclusively affording various 2‐oxazolidinones under mild conditions. It is the first eco‐friendly noble‐metal‐free MOFs catalyst for the cyclization of propargylic amines with CO 2 . DFT calculations uncover that Zn II ions can efficiently activate both C≡C bonds of propargylic amines and CO 2 by coordination interaction. NMR and FTIR spectroscopy further prove that Zn‐clusters play an important role in activating C≡C bonds of propargylic amines. Furthermore, the electronic properties of related reactants, intermediates and products can help to understand the basic reaction mechanism and crucial role of catalyst 1 .