New Copper(I)/DBU Catalyst System for the Carboxylative Cyclization of Propargylic Amines with Atmospheric CO2: An Experimental and Theoretical Study

Carbon dioxide (CO2) is an abundant and renewable feedstock for the production of high-value chemicals. Herein, CuI and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) were employed as an efficient catalyst system to synthesize 2-oxazolidinones through the coupling reaction of CO2 and propargylic amines. It was found that this cost-competitive catalyst system could efficiently catalyze the reaction within only 4 h at atmospheric pressure CO2, and a wide range of substrates were suitable for this reaction. Various target products were obtained in excellent yields. Furthermore, the catalytic mechanism of the CuI/DBU system was investigated by using density functional theory. It was shown that copper(I) and DBU played synergistic roles in activating both the C≡C triple bond and the amino group of propargylic amines in the reaction.