Gold-catalysed reactions of alcohols: isomerisation, inter- and intramolecular reactions leading to C–C and C–heteroatom bonds

Heterogeneous Au and Rh catalysts for cycloisomerization reactions of γ-acetylenic carboxylic acids

Au- and Rh-based heterogeneized catalytic systems have been prepared and analyzed. Their efficiency has been evaluated for the cycloisomerization of γ-acetylenic carboxylic acids leading to valuable γ-alkylidene γ-butyrolactones. Bulk AuO3 was found to be a valuable and easy-to-handle catalyst for selective transformations, whereas [C6mim][AuCl4] presented a high activity and Au/β-zeolite was recyclable.

Gold(I)-catalyzed enantioselective ring expansion of allenylcyclopropanols

The asymmetric gold(I)-catalyzed ring expansion of 1-allenylcyclopropanols is described. The method provides synthetically valuable cyclobutanones with a vinyl-substituted quaternary stereogenic center in high enantioselectivities and yields. The method shows a broad substrate scope, tolerating protected alcohols and amines, alkenes, unsaturated esters, and acetals. The reaction is easily adjustable to large-scale synthesis, leading to product formation without significant loss of selectivity or yield with only 0.5 mol% catalyst loading.

Facile and efficient one-pot synthesis of 2-arylbenzoxazoles using hydrogen tetrachloroaurate as catalyst under oxygen atmosphere

In this paper, we presented a novel method for the facile and efficient one-pot synthesis of 2-arylbenzoxazoles, which were directly synthesized from 2-aminophenol and aldehydes catalyzed by hydrogen tetrachloroaurate (HAuCl(4).4H(2)O) under an oxygen atmosphere with anhydrous tetrahydrofuran (THF) as solvent or in solvent-free condition. The results show that this method could bring excellent yields as high as 96%. THF was proven to be the best choice among several solvents screened and the reaction was tolerated with a variety of aromatic aldehydes possessing electron-donating or withdrawing groups. The advantages of the present method lie in catalytic process using economic and environmentally benign dioxygen as oxidant.

Carbocyclisation of alkynes with external nucleophiles catalysed by gold, platinum and other electrophilic metals

This tutorial review covers recent developments in catalytic carbocyclisation of functionalised alkynes with external nucleophiles catalysed by gold, platinum and other electrophilic metals. Substrates of such reactions require a tethered functionality to react with the alkyne to complete a carbocyclic ring. We classify the reactions according to the tethered functionalities to illustrate the diversity of the carbocyclisations; these substrates include: (1) alkyne-alkyne, (2) alkyne-allene, (3) alkyne-alkene, (4) oxo-alkynes and (5) oxo-diynes and triynes. Besides their mechanistic interest, these reactions meet atom economy criteria because complex and functionalised carbocyclic products are easily assembled in a cascade sequence from readily available alkynes and nucleophiles.