Transition‐Metal Catalyzed Synthesis of N‐Heterocycles using Solvent‐Carbon (C1) Synthons

Nitrogen‐containing heterocycles represent fundamental components found in a myriad of natural compounds, pharmaceuticals, tailored bioactive substances, and agrochemicals. In recent decades, the field of synthetic chemistry has prioritized these compounds, directing considerable research endeavour toward developing efficient and concise methodologies for their synthesis. Consequently, there is a growing interest in pioneering novel synthetic approaches to fabricate these immensely coveted structural motifs. Transition metal‐catalyzed reactions leveraging solvents as carbon (C1) synthons offer notable advantages, including streamlined processes, enhanced atom economy, and environmental sustainability. This review sheds light on the recent advancements in the utilization of collective solvents such as methanol (alongside other alcohols), N,N‐dimethylethanolamine (DMEA), and triethylamine (TEA) (in conjunction with other amines), tetrahydrofuran (THF), toluene, dichloromethane (DCM), dimethyl sulfoxide (DMSO), and dimethylformamide (DMF) as C1 synthons, serving as foundational units for the synthesis of N‐heterocycles, including quinazolinone, quinazoline, quinoxaline, pyridine, and pyrimidine, among others. Various reaction conditions employing diverse transition metals, coupling partners, and solvents as carbon synthons or reagents, as reported in the literature, have been explored. This review highlights the recent advancements in the utilization of collective solvents, such as alcohols, amines, THF, toluene, DCM, DMF, and DMSO, as versatile reagents and carbon (C1) synthons in transition‐metal catalyzed processes for the synthesis of diverse N‐heterocycles. It provides a detailed showcase of reaction conditions, scope, mechanisms, and applications.