Highly Efficient Conversion of Propargylic Alcohols and Propargylic Amines with CO2 Activated by Noble-Metal-Free Catalyst Cu2O@ZIF-8

The cyclization reactions of propargylic alcohols and propargylic amines with CO2 are important in industrial applications, but it was a great challenge that non-noble-metal catalysts catalyzed both reactions under mild conditions. Herein, the catalyst Cu2O@ZIF-8 was prepared by encapsulating Cu2O nanoparticles into robust ZIF-8, and it can effectively catalyze the cyclization of both propargylic alcohols and propargylic amines with CO2 into valuable alpha-alkylidene cyclic carbonates and oxazolidinones with turnover numbers (TONs) of 12.1 and 19.6, which can be recycled at least five times. The mechanisms were further uncovered by NMR, FTIR, C-13 isotope-labeling experiments and DFT calculations, in which Cu2O and DBU can synergistically activate the C equivalent to C bond and the hydroxy/amino group of substrates. Importantly, it is the first example of a noble-metal-free catalyst that can catalyze both propargylic alcohols and propargylic amines with CO2 simultaneously.

Automated summary

The Cu2O@ZIF-8 catalyst was prepared and demonstrated its effectiveness in catalyzing the cyclization reactions of propargylic alcohols and propargylic amines with CO2. This is the first noble-metal-free catalyst to simultaneously catalyze both reactions.