Preparation and Reactivity of Organometallic Reagents Leading to Functionalized N-Heteroaromatics

Main-group organometallic reagents played a pivotal role in organic synthesis, with numerous applications, ranging from pharmaceutical industries to material science. Especially, functionalized heterocyclic molecules may be prepared using main-group organometallics and have multiple applications due to their electronic and chemical properties. This comprehensive review emphasized the significance of functionalized organo-Li, -Mg, -Zn, -Al, -Mn, -Cu, -B, -Na, -La, -In, -Cd, and -Zr reagents for the selective functionalization of N-heteroaromatic scaffolds. Our major focus was on advanced synthetic methods for the preparation of densely functionalized N-heteroaromatic compounds. In recent years, various leading research groups developed highly reactive, air- and moisture-stable organometallic reagents that permitted a broad range of cross-coupling reactions (C-C, C-N, C-S, and C-X) using various electrophiles. We will describe the various preparations of N-heteroromatic organometallics (direct metal insertions, halogen-metal exchanges, transmetalations or directed metalations), showing the advantages and limitations of each method. Moreover, the use of low-cost and less toxic transition-metal-catalyzed processes with air-stable zinc reagents or TMP bases under sustainable conditions, offered alternative synthetic pathways for the preparation of fused N-heteroaromatic-based natural products and drugs. In this context, this review article points to new approaches for the functionalization of N-heteroaromatic scaffolds using various main-group organometallic reagents published between 2010 and 2024.