Sequential Amination/Annulation/Aromatization Reaction of Carbonyl Compounds and Propargylamine:  A New One-Pot Approach to Functionalized Pyridines

Abbiati, Giorgio; Arcadi, Antonio; Bianchi, Gabriele; Giuseppe, Sabrina Di; Marinelli, Fabio; Rossi, Elisabetta

doi:10.1021/jo0347260

Cited by 155 publications

(111 citation statements)

References 37 publications

(44 reference statements)

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“…Even innovative synthesis methods for pyridine derivatives are always within the research interests of synthetic chemists [6][7][8]. This is due to the importance of the pyridine moiety in nearly all fields of chemistry.…”

Section: A-substituted Pyridine Synthesismentioning

confidence: 99%

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Heterogeneous Catalyzed Pyridine Synthesis using Montmorillionite and Nanoparticle‐Impregnated Alumina in a Continuous Micro Flow System

Abahmane¹,

Knauer²,

Ritter³

et al. 2009

Chem Eng & Technol

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The synthesis of pyridine derivatives was investigated using a combined micro flow-through system. Therefore, two different heterogeneous catalyst assemblies were used subsequently under different temperature conditions. The investigated pyridine synthesis method includes three reaction steps: at first, an enamine has to be formed by a condensation reaction of methyl ketone and propargylamine. Secondly, a pericyclic reaction of the enamine is needed to form dihydropyridine derivatives. Finally, the dihydropyrimidines received have to be oxidized to yield the desired pyridine derivative. The propargylamine used tends towards side reactions even if activating catalysts are present at elevated temperatures. To reach high yields for the overall process, each reaction step demands for a specific catalyst and suited reaction conditions. Hence, the reaction sequence was separated into two consecutive steps. For the initial condensation reaction, montmorillionite was investigated as heterogeneous catalyst. For the subsequent reaction steps, different types of nanoparticles impregnated on alumina were investigated as oxidation catalyst, using air as oxidation agent. Here, the results and optimized process conditions for the conversion of aliphatic and aromatic methyl ketones are presented. As a result, the separation of the reaction steps by application of the two-step microreactor system leads to a significant improvement of the process performance. The reaction time was reduced significantly to about 20 minutes without reduction of the product turnover in several cases.

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Section: A-substituted Pyridine Synthesismentioning

confidence: 99%

“…Recently, Arcadi et al described a one-pot synthesis for a-substituted pyridines by the reaction of methyl ketones (1) and propargylamine (2) (see Fig. 1) [6]. In general, three reaction states are involved in this reaction sequence.…”

Section: A-substituted Pyridine Synthesismentioning

confidence: 99%

Heterogeneous Catalyzed Pyridine Synthesis using Montmorillionite and Nanoparticle‐Impregnated Alumina in a Continuous Micro Flow System

Abahmane¹,

Knauer²,

Ritter³

et al. 2009

Chem Eng & Technol

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“…Arcadi et al [25] developed a synthesis of pyridines 32 from carbonyl compounds 29 and propargylamine 30 (Scheme 8). The initial isomerization product is the dihydropyridine 31, which must be dehydrogenated somehow.…”

Section: The Oxidation State Of the Active Species: New Pieces Of Thementioning

confidence: 99%

The Catalysis Gold Rush: New Claims

2005

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“…A new synthesis of pyridines 65, just published by Arcadi et al (48), utilizes both the principle of the electrophilic attack of an alkyne at an electron-rich enamine in the intermediate 64 and in a preceding step the gold-catalysed condensation of ketones 62 with propargyl amines 63, Figure 25 (compare formation of compound 92 in Figure 33). …”

Section: Figure 23mentioning

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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Sequential Amination/Annulation/Aromatization Reaction of Carbonyl Compounds and Propargylamine: A New One-Pot Approach to Functionalized Pyridines

Cited by 155 publications

References 37 publications

Heterogeneous Catalyzed Pyridine Synthesis using Montmorillionite and Nanoparticle‐Impregnated Alumina in a Continuous Micro Flow System

Heterogeneous Catalyzed Pyridine Synthesis using Montmorillionite and Nanoparticle‐Impregnated Alumina in a Continuous Micro Flow System

The Catalysis Gold Rush: New Claims

Homogeneous catalysis by gold

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