Gold-Catalyzed Cascade Reaction of Yne-Enones with Iminooxindoles, Access to 3,2'-Pyrrolidinyl-Spirooxindole Derivatives

Herein, a gold-catalyzed cascade reaction of yne-enones with iminooxindoles has been developed through a cascade cycloisomerization/(3 + 2) annulation process. This approach provides a straightforward and efficient route for the synthesis of functionalized 3,2'-pyrrolidinyl-spirooxindoles in high reactivity and broad substrate scope with excellent cis-selectivity. Moreover, the subsequent functionalization of furan units allows for the diverse synthesis of spirooxindole derivatives, which have demonstrated good antitumoral activity.

Advancements in Gold-Catalyzed Cascade Reactions to Access Carbocycles and Heterocycles: An Overview

This review summarizes recent developments (from 2006 to 2022) in numerous important and efficient carbo- and heterocycle generations using gold-catalyzed cascade protocols. Herein, methodologies involve selectivity, cost-effectiveness, and ease of product formation being controlled by the ligand as well as the counter anion, catalyst, substrate, and reaction conditions. Gold-catalyzed cascade reactions covered different strategies through the compilation of various approaches such as cyclization, hydroarylation, intermolecular and intramolecular cascade reactions, etc. This entitled reaction is also useful for the synthesis of spiro, fused, bridged carbo- and heterocycles.

Yne-Enones Enable Diversity-Oriented Catalytic Cascade Reactions: A Rapid Assembly of Complexity

A small-molecule collection with structural diversity and complexity is a prerequisite to using either drug candidates or chemical probes for drug discovery and chemical-biology investigations, respectively. Over the past 12 years, we have engaged in developing efficient diversity-oriented cascade strategies for the synthesis of topologically diverse skeletons incorporating biologically relevant structural motifs such as O- and N-heterocycles, fused polycycles, and multifunctionalized allenes. In particular, we have highlighted the use of simple, linear, and densely functionalized molecular platforms in these reactions.This account details our efforts in the design of novel molecular platforms for use in metal- and organo-catalyzed cascade reactions, which include 2-(1-alknyl)-2-alken-1-ones (yne-enones) for heterocyclization/cross-coupling cascades, heterocyclization/cycloaddition cascades, nucleophilic addition/cross-coupling cascades, nucleophilic addition/heterocyclization cascades, and so on. Moreover, this Account outlines corresponding mechanistic insights, computational information, and applications of these cascades in the construction of various highly substituted carbo- and heterocycles as well as highly functionalized acyclic compounds, e.g., allenes and dienes. In addition to yne-enones, we evolved the functional groups of our original yne-enones to provide a series of yne-enone variants, which resulted in products with complementary reactivities.The reactivity profile of the yne-enones is defined by the presence of an alkyne moiety and a conjugated enone unit and their mutual through-bond connectivity. Owing to the conceptually rapid development of carbophilic activation, we have identified a series of efficient catalytic systems consisting of metal catalysts, including Pd, Au, and Rh complexes, for diversity-oriented cascade catalysis, allowing various unprecedented reactions to be achieved through different-types of reaction intermediates, including all-carbon metal 1,n-dipoles, furan-based o-quinodimethanes (oQDMs), and allenyl-metal species. In addition to commonly known transition-metal catalytic activity, the Lewis acidity of these complexes is crucial to accomplish the corresponding transformation. In addition, highly enantioselective gold(I)-catalyzed heterocyclization/cycloaddition cascades of yne-enones and their variants were achieved by the application of bisphosphines (e.g., Cn-TunePhos), monophosphines, and our developed "Ming-Phos" as chiral ligands. Importantly, Ming-Phos ligands exhibited excellent performance in gold-catalyzed mechanistically distinct [3 + n]-cycloaddition reactions, in which the chiral sulfinamide moiety is possibly responsible for the interaction with the substrate to control enantioselectivity. Subsequently, we demonstrated that the easily prepared polymer-supported Ming-Phos ligand could be applied for heterogeneously gold(I)-catalyzed asymmetric cycloaddition with good stereocontrol. With metal-free catalysis, the divergent functionalization of yne-enones provides numerous synthetic outlets for structure diversification. For example, yne-enones are particularly attractive for use as precursors of various chiral and achiral heterocycles, such as pyrazoles, isoxazoles, pyrroles, and pyrans, etc.

Silver & gold-catalyzed routes to furans and benzofurans

Silver and gold have become incredibly versatile and mild catalysts for numerous transformations, especially in heterocycle synthesis. For the most prominent of them, i.e. furans, silver and gold, with their unique reactivity and mildness, allow numerous possible routes to highly substituted and/or functionalized furans from a large variety of starting materials. Silver and gold catalysis provide thus the most flexible way to this important family of compounds. The present review describes these silver and gold-catalyzed routes, with some emphasis on mechanistic aspects, and proposes a comparison of both the silver and the gold-catalyzed syntheses of furans.

Exploring the gold mine: [Au]-catalysed transformations of enynals, enynones and enynols

This review highlights reactions of enynals, enynones and enynols using gold catalysis which often lead to cycloaddition or cyclisation products.

Sc(OTf)3-catalyzed cyclization of α-allylated 1,3-dicarbonyls: an efficient access to 2,2-disubstituted 2,3-dihydrofuran derivatives

A Sc(OTf)₃-catalyzed cyclization of α-allylated 1,3-dicarbonyls is reported. By the reaction, a variety of 2,2-disubstituted 2,3-dihydrofurans were obtained in good yields.