Palladium‐catalyzed Synthesis of Fused Carbo‐ and Heterocycles

Abstract

The use of palladium catalysts in fused ring synthesis has been increasingly noteworthy in recent years in organic synthesis. It has a lot of potential compared to other transition metal catalysts, because of its one-of-a-kind feature that makes them more widely applicable in a variety of disciplines application. Palladium is important in a variety of Heck processes, including intramolecular, intermolecular, and reductive Heck reactions, which produce diverse carbocycles and heterocycles of biological importance. Under optimal reaction conditions, carbocyclization or heterocyclization occurs, resulting in the production of numerous structural building blocks of naturally occurring compounds. Beside intramolecular Heck-type reactions, cycloaddition, cycloalkylation, oxidative coupling, CÀ H functionalization, cross-coupling reactions, and carboamidation reactions have also been employed extensively to access fused carbo-and heterocycles of immense biological importance. This review article provides a well-summarized discussion (since 2001) on fused carbo-and heterocycle ring synthesis using palladium catalysts, overviewing their applications, and mechanistic insights.

Transition‐Metal Catalyzed [4+2]‐Cycloaddition Reactions: A Sexennial Update

“…Among a variety of synthetic methods to synthesize sixmembered carbocyclic skeletons via transition metals, Palladium has been the most preferred metal by organic chemists to generate new CÀ C, CÀ N and CÀ O bonds in order to produce a diverse range of carbo-and heterocyclic bioactive scaffolds. [26] Also, Pd-catalyzed cycloaddition reactions involving zwitterionic allylpalladium intermediates are incredibly useful for building spirocyclic moieties. [27] Particularly, vinyl benzoxazinanones serve as transient zwitterionic palladium stabilized-π-allyl intermediates for the formation of [4 + 2] cycloadducts.…”

Recent Advances in the Synthesis of Five‐membered Nitrogen Heterocycles Induced by Palladium Ions and Complexes

“…The review by Ghosh et al . specifically addresses the formation of fused ring systems as a widely applicable possibility taking place via carbocyclization or heterocyclization [10] . This approach is of particular interest in the building of nitrogen‐containing blocks of naturally occurring compounds available via palladium catalysis.…”

Recent developments in nickel-catalyzed asymmetric cyclization and cycloaddition of carbonyl-alkynes, cyano-alkynes, and enynes

“…2 For many years, palladium-catalyzed chemical transformations have dominated the field of transition metal catalysis, and numerous synthetically challenging carbon–carbon or carbon–hetero bonds have been constructed on the basis of palladium catalysis. 3 Along with the significant progress being achieved in palladium chemistry, the exploration of other transition metal catalysts in cyclization reactions has also attracted much attention from many synthetic chemists and has recently turned out to be the mainstream direction in transition metal catalysis. In the past decade, nickel, a low-cost and more readily available transition metal catalyst, has been continuously explored in a variety of chemical transformations and also achieved great development.…”