Recent Advances in One-Pot Modular Synthesis of 2-Quinolones

Abstract

It is known that 2-quinolones are broadly applicable chemical structures in medicinal and agrochemical research as well as various functional materials. A number of current publications about their synthesis and their applications emphasize the importance of these small molecules. The early synthetic chemistry originated from the same principle of the classical Friedländer and Knorr procedures for the preparation of quinolines. The analogous processes were developed by applying new synthetic tools such as novel catalysts, the microwave irradiation method, etc., whereas recent innovations in new bond forming reactions have allowed for novel strategies to construct the core structures of 2-quinolones beyond the bond disconnections based on two classical reactions. Over the last few decades, some reviews on structure-based, catalyst-based, and bioactivity-based studies have been released. In this focused review, we extensively surveyed recent examples of one-pot reactions, particularly in view of modular approaches. Thus, the contents are categorized as three major sections (two-, three-, and four-component reactions) according to the number of reagents that ultimately compose atoms of the core structures of 2-quinolones. The collected synthetic methods are discussed from the perspectives of strategy, efficiency, selectivity, and reaction mechanism.

Unexpected Cascade Dehydrogenation Triggered by Pd/Cu-Catalyzed C(sp3)–H Arylation/Intramolecular C–N Coupling of Amides: Facile Access to 1,2-Dihydroquinolines

“…They can be conveniently converted to complex organic compounds through C–H functionalization, asymmetric olefin difunctionalization, and N functionalization . Due to its significance, the synthesis of the DHQ skeleton has received a lot of attention, and numerous elegant methodologies have been created, including the Skraup reaction, transition-metal-catalyzed annulation of anilines with alkynes, ring-closing metathesis, intramolecular allylic amination, partial transfer hydrogenation of quinolines, and others . However, some limitations still urgently must be overcome.…”

Synthesis of N-CF3 Alkynamides and Derivatives Enabled by Ni-Catalyzed Alkynylation of N-CF3 Carbamoyl Fluorides

“…Quinolones and oxindoles appear in anticancer drugs and have anti-inflammatory and antibacterial properties. − , Indeed, their importance is underscored by the continual development of synthetic routes to these scaffolds. − However, the N -CF 3 variant of either motif has not yet been synthetically accessible. Further validating our N -CF 3 alkynamides as building blocks, the application of a cationic gold catalyst afforded the 2-quinolone 29 .…”

Diversity-Oriented Synthesis: Amino Acetophenones as Building Blocks for the Synthesis of Natural Product Analogs

“…One of the targeted structural modifications of phenylcoumarins is the substitution of the pyrane ring's oxygen atom with a nitrogen, giving 3-phenyl-2-quinolones (Figure 2). 2-Quinolones are known for a broad spectrum of medicinal applications as drugs used in respiratory diseases, antiulcer agents, and as antiparasitic drugs [59]. Among them, 3-aryl-2-quinolones were reported as modulators of the efflux pumps involved in multi-resistant Staphylococcus aureus bacteria [60] and as anticancer agents [61].…”