Highly Efficient Conversion of Propargylic Amines and CO Catalyzed by Noble-Metal-Free [Zn ] Nanocages.

The reaction of propargylic amines and CO 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 ] nanocage in zinc-tetrazole 3D framework [Zn (Trz) (OH) (H O) ⋅8 H O] Trz=(C N O) (1) was obtained and structurally characterized. It consists of six [Zn O ] clusters and eight [Zn O ] 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 , 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 . DFT calculations uncover that Zn ions can efficiently activate both C≡C bonds of propargylic amines and CO 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.