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

Abstract

Gold catalysed synthesis of carbo-/hetero-cyclic compounds is currently a topic of intense activity thanks to the unique properties bestowed upon gold by relativistic effects, the potential of which has been realised mainly during the past two decades. This review will dwell upon the reactions involving gold catalysis in which enynal, enynone or enynol is one of the reacting partners. Most often these reactions lead to fused hetero-/homo-cycles under mild conditions with environmentally benign byproducts. Thus an opportunity for the organic community to develop new methodologies, efficient asymmetric variants, and application in total synthesis by [Au]-catalysis has emerged.

Alcohol Dehydrogenases and N‐Heterocyclic Carbene Gold(I) Catalysts: Design of a Chemoenzymatic Cascade towards Optically Active β,β‐Disubstituted Allylic Alcohols

“…With that purpose and due to the large p-acidic character of Au complexes,t he selection of alkynes as benchmark substrates flourish as aw ise choice based on the diverse chemical possibilities of this pair Au-alkyne. [37][38][39][40][41] Interestingly,abroad number of organic transformations can be successfully accomplished such as cyclization,h ydration, redox isomerization or rearrangements such as the Rupe or Meyer-Schuster ones (Scheme 1), [42][43][44][45][46] gold N-heterocyclic carbenes (NHCs) playing ar elevant role in the catalysis of these type of chemical processes. [47][48][49] TheMeyer-Schuster rearrangement consists in the transformation of propargylic (acetylated) alcohols into the corresponding a,b-unsaturated carbonyl compounds,r equiring metal catalysis (Cu, Sc, Hg, Ag, Au,In…), and traditionally performed under harsh reaction conditions (organic solvent, acidic catalysis,h igh temperature.).…”

Triflic Acid Promoted Transformations of Linear‐Conjugated Enynones and their Reactions with Arenes. Synthesis of Dihydropyranones, Conjugated Dienones, and Indanes

“…Nowadays, different linear‐ and cross‐conjugated enynones are widely used in organic synthesis (see recent reviews [1–5] on this topic). However, among all enynone structures, the linear‐conjugated pent‐4‐en‐2‐yn‐1‐ones [>C=C(R)−C≡C−C(R′)=O] still remain sparsely investigated.…”

Gold-Catalyzed Homogeneous (Cyclo)Isomerization Reactions

“…It is organized according to both the kind of substrates to be activated by the gold complex: Allenes, 1, n -dienynes and 1, n -diynes and to the first mechanistic step in the global transformation such as carbocyclization, nucleophilic attack or carbonate/ester group rearrangement processes. Due to the overwhelming number of studies and the recently published reviews about gold-mediated isomerization reactions (Belmont and Parker, 2009; Fensterbank and Malacria, 2014; Yang and Hashmi, 2014; Dorel and Echavarren, 2015; Asiri and Hashmi, 2016; Day and Chan, 2016; Maes et al, 2016; Quintavalla and Bandini, 2016; Siva Kumari et al, 2016; Wei and Shi, 2016; García-Morales and Echavarren, 2018; Lee and Kumar, 2018; McGee et al, 2018; Toullec and Michelet, 2018), we will include here the most relevant contributions of the last years.…”