Palladium-catalyzed ring-forming reactions: Methods and applications

Abstract

Several Pd-catalyzed cyclization methods were developed, including norbornenemediated Catellani-type reactions, a Pd-catalyzed coupling reaction of aryl iodides and allyl moieties, and a tandem C-N/C-C coupling of gem-dihalovinyl systems. These ring-forming methods were applied to the synthesis of highly functionalized carbocyclic and heterocyclic compounds. Intermolecular Pd-catalyzed methods for synthesis of highly substituted arene compounds were also developed.

Transition‐Metal‐Catalyzed Direct Arylation of (Hetero)Arenes by CH Bond Cleavage

“…Thereafter, a sequence consisting of formal oxidative addition and reduc- Although there is evidence for the formation of palladium(IV) intermediates in comparable functionalizations of ortho-CÀH bonds when using alkyl halides, [110,112] recent studies suggest that the palladium(IV) species are not the relevant intermediates in the arylation with bromides. [154] Valuable recent applications of this powerful concept towards the direct arylation of (hetero)arenes were designed by Lautens et al [155] For example, polycyclic 2H-indazoles were obtained by a palladium-catalyzed annulation (Scheme 77), [156] and a direct arylation/cyanation sequence afforded substituted benzonitriles (Scheme 78). [157] An elegant reaction sequence based on a catalytic direct arylation involving palladium migration was realized by Larock and co-workers.…”

Übergangsmetallkatalysierte direkte Arylierungen von (Hetero)Arenen durch C‐H‐Bindungsbruch

“…[154] Wertvolle Anwendungen dieses leistungsfähigen Verfahren zur direkten Arylierung von (Hetero)arenen wurden von Lautens et al entworfen. [155] Beispiele sind die Synthese von polycyclischen 2H-Indazolen durch eine palladiumkatalysierte Anellierung (Schema 77) [156] oder die direkte Arylierungs-/Cyanierungs-Sequenz zur Synthese von substituierten Benzonitrilen (Schema 78). [157] Einige elegante Reaktionsfolgen, die auf einer direkten Arylierung unter Palladium-Wanderung beruhen, wurden von Larock et al realisiert.…”

High‐Oxidation‐State Palladium Catalysis: New Reactivity for Organic Synthesis

“…[10] This seminal reaction is based on the use of norbornene as a shuttle for the construction of up to three new bonds in a domino sequence. [11] A proposed s-norbornyl Pd IV intermediate is central to the overall success of the reaction. Its existence was not proven outright, but derived from the isolation of phenanthroline-stabilized allyl and benzyl model compounds, such as A and B.…”