Recent Developments in Palladium-Catalyzed Oxidative Cascade Carbocyclization

Abstract

In this Perspective, we describe recent advances on Pd-catalyzed oxidative cascade carbocyclizations. These cascade processes enable efficient construction of the molecular complexity and structural diversity of carbocyclic compounds via introducing diverse functionalities concomitant with multiple C–C bond-formations in one-pot operations. In many cases, these processes are facilitated by Pd-catalysts alone, while cocatalysis by combination of Pd catalyst and other catalysts are also discussed, since they represent a new entry to address the preparation of functionalized cyclic compounds with high efficiency and selectivity.

Intramolecular Remote C–H Activation via Sequential 1,4-Palladium Migration To Access Fused Polycycles

“…In the past two decades, palladium-catalyzed C–H functionalization has provided an efficient method for constructing carbon–carbon or carbon–heteroatom bonds, which has been widely employed to the rapid synthesis of natural products and biologically active compounds . In this context, σ-chelation-directed ortho -C–H activation of aromatic compounds via a conformationally rigid five- or six-membered palladacycle intermediate has been substantially explored; however, the selective activation of remote C–H bonds (meta or para position) of arenes is still a difficult task due to the distance and geometry within the substrates.…”

Palladium Catalyzed Aza-Wakcer/Povarov Reaction of Aryl Amines and 1,6-Dienes: Synthesis of Hexahydro-Cyclopenta[b]quinoline Framework

“…We propose the utilization of highly electrophilic palladium as a viable solution, which not only facilitates the aza-Wacker process by activating ole ns to promote subsequent nucleophilic attack, but also facilitates the Povarov cyclization with palladium serves as a Lewis acid. Drawing from recent advances in diene cyclization [53][54][55][56][57] , we present a novel palladium catalyzed reaction of anilines with 1,6-dienes to synthesize hexahydro-cyclopenta[b]quinolines, seamlessly integrating two classic named reactions into one-pot, which is attributed to the utilization of a highly electrophilic palladium catalyst activated by NaBAr F 4 (Scheme 1c).…”

Palladium-Catalyzed Dehydrogenative Carbonylative Esterification of Allenoic Acids for the Synthesis of γ-Butyrolactone Derivatives

“…The oxidative functionalization of allenes, catalyzed by transition-metals, particularly palladium oxidation, has garnered significant interest and been effective in diverse transformations, including carbocyclization, acetoxylation, arylation, carbonylation, borylation, β-alkynylation, acyloxylation, and olefination . These reactions facilitate the synthesis of various challenging targets, including cyclobutenes, seven-membered carbocycles, helical derivatives, functionalized cyclohexenes, and chiral cyclopentanone derivatives, with excellent chemo-, stereo-, and regioselectivity . For example, Gulías and co-workers developed an efficient stereoselective synthesis of benzoxepine compounds from allenes using Pd­(OAc) 2 as catalyst .…”