Bidentate Ligand-Engineered MOF-Based Cu Single-Atom Catalyst for Selective Conversion of Organic Azides into Unsymmetrical Carbonyls via Functionalized Building Units and Atomic Regulation

The construction of unsymmetrical molecular structures has been a long-standing challenge in organic chemistry, particularly in the field of unsymmetrical carbonyls, which requires precise control over reaction selectivities. In this study, we introduced an innovative protocol that facilitates the one-step, completely selective preparation of a series of unsymmetrical carbonates, ureas, and carbamates from conventional carbonyl azides with the complete dissociation of the azido group. Leveraging the structural programmability of metal-organic frameworks (MOFs), we implemented a dual-modification strategy involving: (i) precise tailoring of functional building blocks with Schiff-base linkage to construct the microenvironment of the scaffold and (ii) coordination of copper species onto the predesigned N,N-bidentate ligand, ultimately fabricating a MOF-based Cu single-atom catalyst with defined activities. Furthermore, density functional theory (DFT) calculations revealed that the activation of nucleophiles and the subsequent attack on the carbonyl group are involved in the rate-determining step. The protocol not only allows for fine-tuned modulation of the Cu coordination environment but also ensures stable immobilization of Cu single atoms. This work underscores the pivotal role of a single-atom catalyst in the transformation of organic azides into unsymmetrical carbonyls, as well as their critical contribution in reactivity and selectivity control in organic synthesis.