Hoch effiziente Synthese des Erythrina‐ und B‐Homoerythrina‐Gerüsts über eine AlMe<sub>3</sub>‐vermittelte Dominoreaktion

Domino reactions are defined as processes of two or more bond-forming reactions under identical conditions, in which the subsequent transformation takes place at the functionalities obtained in the former transformation. They allow the efficient synthesis of complex molecules from simple substrates in an ecologically and economically favorable way.A very powerful domino process is the domino Knoevenagel-hetero-Diels-Alder reaction, in which an aldehyde or an β-ketoester is condensed with a 1,3-dicarbonyl compound or a heteroanalog to give a 1-oxa-1,3-butadiene, which can undergo an inter-or intramolecular hetero-Diels-Alder reaction with dienophiles such as enol ethers or alkenes.The products are dihydropyrans, which can be transformed in a variety of ways. Thus, an extension of the process is the synthesis of highly substituted pyrrolidines, piperidines, and azepanes using aminoaldehydes. The process has also been employed for the enantioselective total synthesis of a variety of alkaloids, such as indol-and ipecacuanha alkaloids. In another domino process, erythrina and homoerythrina alkaloids have been prepared from simple phenylethylamines and ketoesters.

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“…The procedure was used for the synthesis of the skeleton of the erythrina and homoerythrina alkaloids [27].…”

confidence: 99%

Domino reactions in the synthesis of heterocyclic natural products and analogs

Tietze

Rackelmann

2004

Pure and Applied Chemistry

454

106

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“…On the other hand, the multi-step synthesis towards a complex compound is laborious and tedious, generating several equivalents of waste and salt as by-products. Hence, domino processes, in an environmentally benign and atomeconomic fashion, [1,2] play an important role in organic syntheses, especially considering that certain complex compounds such as fused polyheterocycles [1,3,4] are of great significance and their synthesis still remains a challenge for chemists.…”

Section: Introductionmentioning

confidence: 99%

Domino Reaction of Acyclic α,α‐Dialkenoylketene S,S‐Acetals and Diamines: Efficient Synthesis of Tetracyclic Thieno[2,3‐b]thiopyran‐Fused Imidazo[1,2‐a]pyridine/Pyrido[1,2‐a]pyrimidines

et al. 2006

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A series of unusual fused tetraheterocyclic compounds 3, consisting of a thiopyran (ring A), a thiophene (ring B), a pyridine (ring C), and an imidazole or a pyrimidine (ring D) core, with a bridgehead nitrogen and an angular methyl group, were successfully synthesized by a catalyst-free, one-pot, two-component domino reaction of 4-(4-methyl-1,3-dithiol-2-ylidene)-1,7-bis(aryl/heteroaryl)hepta-1,6-diene-3,5-dione 2 and diamines. In this reaction, up to five new bonds were formed accompanied by the C À S bond cleavage of the 1,3-dithiole ring of 2, with water as the only by-product.

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Zinc‐Catalyzed Domino Hydroamination–Alkyne Addition

et al. 2010

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The first zinc-catalyzed one-step synthesis of quaternary propargylamines with four different substituents is described. The domino hydroamination-alkyne addition reaction gives access to functionalized propargylamines under mild conditions. Keywords: alkynes; domino reaction; hydroamination; metathesis; propargylamines; zinc The synthesis of fine chemicals and natural products is often a multistep process including salt-generating reactions. Nowadays the modern synthesis design demands for efficient techniques to minimize the number of steps towards the product and to avoid the formation of by-products. Domino and cascade reactions allow an ecologically and economically favourable synthesis. [1][2][3] These procedures describe closely coupled individual reactions that yield a product in a single process.The addition of an organic amine to C-C multiple bonds presents a challenging and demanding topic. The metal-catalyzed hydroamination has been studied with different types of catalysts. [4][5][6][7] We have reported the metal-catalyzed hydroamination reactions with a diversity of zinc complexes.[6] Hydroamination reactions of alkynes often resulted in the formation of unstable intermediates like enamines and imines and hence were reduced to the corresponding amines in a one-pot procedure. [7] Hydroaminations were also combined in a tandem process with several other reactions like Cope rearrangement, [8] hydroarylation, [9] hydrosilylation [10] and with diverse addition reactions. [11] We are interested in a combination of hydroamination and alkyne addition in a catalytic domino process yielding propargylamines. Such a sequence has not been described intensively and only a few cases are known. In the first report acetylene was converted in a copper-catalyzed reaction to propargyl-A C H T U N G T R E N N U N G amines having a secondary carbon center.[12] These copper-catalyzed reactions have been recently described with diverse phenylacetylenes.[13] The hydro-A C H T U N G T R E N N U N G amination leads to anti-Markovnikov products and the following alkyne addition thus yields a propargyl-A C H T U N G T R E N N U N G amine with a secondary carbon center. In case of a Zn/Cd catalyst the Markovnikov addition was observed but only propyne and dimethyl-or diethyl-A C H T U N G T R E N N U N G amine were used under drastic conditions.[14] Herein we describe a flexible zinc-catalyzed one-step synthesis of quaternary propargylamines with four different substituents. The reaction proceeds under mild conditions and tolerates different functional groups.During our studies on zinc-catalyzed hydroaminations we found that b-diiminate (BDI) complexes like 1 in presence of cocatalyst 2 lead to the catalytically active species 3 (Scheme 1). According to our results, the cocatalyst 2 protonates the precatalyst 1 irreversibly forming methane and generates the catalyst 3 as a cationic BDI-zinc complex with a low-coordinating triflate anion. We confirmed the molecular structure of 3·THF by single crystal X-ray diffraction...

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Hoch effiziente Synthese des Erythrina‐ und B‐Homoerythrina‐Gerüsts über eine AlMe₃‐vermittelte Dominoreaktion

Cited by 6 publications

References 31 publications

Domino reactions in the synthesis of heterocyclic natural products and analogs

Domino reactions in the synthesis of heterocyclic natural products and analogs

Domino Reaction of Acyclic α,α‐Dialkenoylketene S,S‐Acetals and Diamines: Efficient Synthesis of Tetracyclic Thieno[2,3‐b]thiopyran‐Fused Imidazo[1,2‐a]pyridine/Pyrido[1,2‐a]pyrimidines

Zinc‐Catalyzed Domino Hydroamination–Alkyne Addition

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Hoch effiziente Synthese des Erythrina‐ und B‐Homoerythrina‐Gerüsts über eine AlMe3‐vermittelte Dominoreaktion

Cited by 6 publications

References 31 publications

Domino reactions in the synthesis of heterocyclic natural products and analogs

Domino reactions in the synthesis of heterocyclic natural products and analogs

Domino Reaction of Acyclic α,α‐Dialkenoylketene S,S‐Acetals and Diamines: Efficient Synthesis of Tetracyclic Thieno[2,3‐b]thiopyran‐Fused Imidazo[1,2‐a]pyridine/Pyrido[1,2‐a]pyrimidines

Zinc‐Catalyzed Domino Hydroamination–Alkyne Addition

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Product

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Hoch effiziente Synthese des Erythrina‐ und B‐Homoerythrina‐Gerüsts über eine AlMe₃‐vermittelte Dominoreaktion