Recent strategies and developments in the hydroboration of N-Heteroarenes mediated by transition and rare-earth metal complexes

The dearomatization reactions of N-heteroarenes have emerged as crucial chemical transformations in the fields of organic synthesis and medicinal chemistry. These reactions permit the formation of aza compounds, including dihydropyridines, which serve as versatile synthetic building blocks and structural motifs for various bioactive natural products and pharmaceuticals. Over the past few years, dearomative hydroboration has grown into a powerful alternative to traditional reduction methods for N-heteroarenes. This option has demonstrated exceptional selectivity and a high tolerance for different functional groups, indicating great promise. This review provides an emerging overview of selective dearomative hydroboration reactions of N-heterocycles, including pyridines and quinolines. This review encompasses the period from 2014 to the present, examining 31 highly effective catalytic systems that feature d- and f-block metal complexes.