Condensation reactions of benzaldehyde catalysed by gold alkoxides

Komiya, Sanshiro; Sone, Takuo; Usui, Yoko; Hirano, Masafumi; Fukuoka, Atsushi

doi:10.1007/bf03214748

Cited by 46 publications

(21 citation statements)

References 7 publications

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“…By reaction with an equimolar amount of phenol in benzene they are converted into the phenoxogold(I) complexes, thus indicating the higher stability of the latter derivatives with respect to the alkoxides (40). Catalytic amounts of complexes 28 are found to promote Knöevenagel condensation reactions between benzaldehyde and the active methylene compounds CH2(X)(Y) which are able to react with 28 as indicated in Equation 16 (7). The Cbonded gold enolates likewise formed are the active catalysts for the condensation reaction.…”

Section: Oxo Complexesmentioning

confidence: 99%

“…Gold(III) complexes with oxygen donor ligands, such as ␤-diketones or alkylsiloxides, are likewise employed as precursors for chemical vapour deposition (CVD) (6). Another promising result in the field of homogeneous catalysis is the discovery that gold(I) and gold(III) alkoxo complexes promote the condensation of benzaldeyde with compounds containing an active methylene group (7). Hence it appears that gold complexes with oxygen donor ligands are of relevant technological interest.…”

mentioning

confidence: 99%

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Gold(I) and gold(III) complexes with anionic oxygen donor ligands: hydroxo, oxo and alkoxo complexes

Cinellu

Minghetti

2002

Gold Bull

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Section: Oxo Complexesmentioning

confidence: 99%

mentioning

confidence: 99%

Gold(I) and gold(III) complexes with anionic oxygen donor ligands: hydroxo, oxo and alkoxo complexes

Cinellu

Minghetti

2002

Gold Bull

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“…Komiya et al discovered that Au(I)-and Au(III)-alcoholates catalyse Knoevenagel condensations under neutral conditions (28). Acceptor-substituted methylene compounds 33 react with aldehydes 32 to provide alkenes 34, Figure 17.…”

Section: Figure 13mentioning

confidence: 99%

Homogeneous catalysis by gold

2004

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A comprehensive overview in the field of homogeneous catalysis by gold is given and the basic principles are discussed. It is also highlighted where homogeneous gold catalysts are already superior to other catalysts and where future possibilities for advantageous use of homogeneous gold catalysts exist.For a long time, gold was considered to possess only low catalytic activity ("catalytically dead") and therefore only its stoichiometric co-ordination and organo-metallic chemistry was investigated intensively. Even in the 19th century it was quite popular to characterize precious alkaloid bases after their troublesome isolation from natural sources as tetrachloroaurates (1,2).Since then, a change of paradigm has taken place (3). Among the numerous applications for gold, its use as a catalyst, albeit not yet consuming large amounts of this metal, has attracted much attention. Overall, in the chemical databases ca. 230,000 papers on gold can be found, of which about 9,000 deal with gold catalysis (from the SciFinder database in October 2003). The field of gold catalysis is dominated by heterogeneous catalysts, while homogeneous catalysts still represent the much smaller part (about 100 hits). Still, a significant amount of different homogeneous gold-catalysed reactions is known and basic principles can be deduced from them.In this article only publications in which gold is unambiguously the site of the catalysis reaction will be covered. This, for example, excludes the use of some mixed metal clusters and mixed metal colloids. BackgroundHomogeneous catalysis includes all reactions in which the substrate(s) and the catalyst are in the same state. As there exists only a limited number of highly volatile gold compounds, most of these reactions are conducted in the liquid phase with either liquid or dissolved substrate(s) and a dissolved catalyst. Homogeneous catalysis in the solid state, a part of the solvent-free reactions (4) that are nowadays quite popular in the field of green chemistry, has not been explored with gold yet (with the exception shown in Figure 31)! In this context, the non-toxicity of gold, which helps to avoid any environmental problems, is also of importance.The catalyst itself promotes a chemical reaction, a process in which chemical compounds (the substrates) are converted to other chemical compounds (the products), to proceed under milder reaction conditions (lower temperatures, lower pressure, lower concentrations of the substrates, higher or different selectivity). As the catalyst is not consumed, a catalytic amount is sufficient -but this is often a matter of debate: for some scientists 20 mol% of 'catalyst' are still catalytic, while others may consider this to be a substoichiometric reaction and accept only 0.001 mol% or less as catalytic.Two motives drive the desire to produce a chemical reaction: The use of gold as a catalyst is desirable when it has a similar activity as for a more expensive catalyst, when it shows a higher activity or a higher selectivity than less expensive catalysts...

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“…Reactions triggered by s-Lewis acid activation modes have been relatively ignored and the synthetic potential of this complementary approach has risen to prominence only quite recently. Early literature reports in this area were mainly devoted to Lewis acid activation of carbonyl compounds, [3,4] but recent reports have shown that Au I and Au III salts are also competent catalysts in the mediation of dehydrative couplings of activated p alcohols (and their ether or ester derivatives) with many types of carbo-and heteronucleophiles. [5] Highly reactive substrates such as doubly p-activated alcohols, that is, precursors of well-stabilized cations, have generally been used in intermolecular reactions [6a-n] whereas gold-catalyzed intramolecular dehydrative couplings with good neutral nucleophiles (indoles, heteronucleophiles) tolerated less reactive substrates such as simple primary allylic alcohols.…”

Section: Introductionmentioning

confidence: 99%

Dual Hard/Soft Gold Catalysis: Intermolecular Friedel–Crafts‐Type α‐Amidoalkylation/Alkyne Hydroarylation Sequences by N‐Acyliminium Ion Chemistry

Boiaryna

Mkaddem

Taillier

et al. 2012

Chemistry A European J

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Gold catalysts have been applied in cascade-type reactions for the synthesis of different nitrogen-based compounds. The reactions likely proceed by a new gold-catalyzed cascade intermolecular α-amidoalkylation/intramolecular carbocyclization cascade process by unifying both the σ- and π-Lewis acid properties of the gold salts. In the first part of this report we show that the σ-Lewis acidity of gold(I) and gold(III) could be exploited to efficiently catalyze the nucleophilic substitution of various alkoxy- and acetoxylactams. The reaction was found to be applicable to a wide range of cyclic N-acyliminium ion precursors and various nucleophiles, including allyltrimethylsilane, silyl enol ethers, arenes, and active methylene derivatives. As a logical progression of this study, a combined hard/soft binary catalytic gold system was then used to implement an unprecedented tandem intermolecular Friedel-Crafts amidoalkylation/intramolecular hydroarylation sequence allowing an expedient access to new, complex, fused polyheterocyclic structures from trivial materials.

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Condensation reactions of benzaldehyde catalysed by gold alkoxides

Cited by 46 publications

References 7 publications

Gold(I) and gold(III) complexes with anionic oxygen donor ligands: hydroxo, oxo and alkoxo complexes

Gold(I) and gold(III) complexes with anionic oxygen donor ligands: hydroxo, oxo and alkoxo complexes

Homogeneous catalysis by gold

Dual Hard/Soft Gold Catalysis: Intermolecular Friedel–Crafts‐Type α‐Amidoalkylation/Alkyne Hydroarylation Sequences by N‐Acyliminium Ion Chemistry

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