Reductive Coupling of Nitroarenes and HCHO for General Synthesis of Functional Ethane-1,2-diamines by a Cobalt Single-Atom Catalyst

Despite the extensive applications,selective and diverse accessto N,N & PRIME;-diarylethane-1,2-diamines remains,to date, a challenge. Here, by developing a bifunctional cobalt single-atomcatalyst (Co-SA-N/NC), we present a general method for directsynthesis of such compounds via selective reductive coupling of cheapand abundant nitroarenes and formaldehyde, featuring good substrateand functionality compatibility, an easily accessible base metal catalystwith excellent reusability, and high step and atom efficiency. Mechanisticstudies reveal that the N-anchored cobalt single atoms (CoN4) serve as the catalytically active sites for the reduction processes,the N-doped carbon support enriches the HCHO to timely trap the in situ formed hydroxyamines and affords the requisite nitronesunder weak alkaline conditions, and the subsequent inverse electrondemand 1,3-dipolar cycloaddition of the nitrones and imines followedby hydrodeoxygenation of the cycloadducts furnishes the products.In this work, the concept of catalyst-controlled nitroarene reductionto in situ create specific building blocks is anticipatedto develop more useful chemical transformations.