A general and efficient method for synthesis of enaminones and enamino esters catalyzed by NbCl5 under solvent-free conditions

Yu-Heng, Liu; Wang, Ping; Cheng, Gui-Tian

doi:10.1007/s00706-012-0783-8

Cited by 6 publications

(2 citation statements)

References 48 publications

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“…Scheme illustrates the proposed mechanism for the formation of β-enaminone 17 . A variety of Lewis acids − have been reported to catalyze the formation of β-enaminones analogous to 17 . Catalysis by Sn 4+ has been reported, but not to our best knowledge by Sn 2+ .…”

Section: Discussionmentioning

confidence: 99%

Effect of Bronsted Acids and Bases, and Lewis Acid (Sn²⁺) on the Regiochemistry of the Reaction of Amines with Trifluoromethyl-β-diketones: Reaction of 3-Aminopyrrole to Selectively Produce Regioisomeric 1H-Pyrrolo[3,2-b]pyridines

et al. 2015

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Reaction of 3-aminopyrrole (as its salt) with trifluoromethyl-β-diketones gave γ-1H-pyrrolo[3,2-b]pyridines via reaction at the less reactive carbonyl group. The trifluoromethyl group increased the electrophilicity of the adjacent carbonyl group and decreased the basicity of the hydroxyl group of the CF3 amino alcohol formed. This amino alcohol was formed faster, but its subsequent dehydration to the β-enaminone was slow resulting in the preferential formation of the γ-regioisomer. Reaction of 4,4,4-trifluoro-1-phenyl-1,3-butadione with 3-aminopyrrole was carried out using a series of 6 amine buffers. Yields of the α-1H-pyrrolo[3,2-b]pyridine increased as the pKa of the amine buffer decreased. Surprisingly the yield went down at higher pKas. There was a change in mechanism as the reaction mixture became more basic. With strong amines trifluoromethyl-β-diketones were present mainly or completely as the enolate. Under reductive conditions (3-nitropyrrole/Sn/AcOH/trifluoromethyl-β-diketone) the α-1H-pyrrolo[3,2-b]pyridine was the major product as a result of Lewis acid catalysis by Sn(2+). Similar α-regiochemistry was observed when the reaction of the 3-aminopyrrole salt with trifluoromethyl-β-diketones was carried out in the presence of base and tin(II) acetate.

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Section: Discussionmentioning

confidence: 99%

Effect of Bronsted Acids and Bases, and Lewis Acid (Sn²⁺) on the Regiochemistry of the Reaction of Amines with Trifluoromethyl-β-diketones: Reaction of 3-Aminopyrrole to Selectively Produce Regioisomeric 1H-Pyrrolo[3,2-b]pyridines

et al. 2015

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“…NbCl 5 forms chloro-bridged dimers in its solid state in which each niobium atom is surrounded by a distorted octahedron of chlorine atoms. NbCl 5 is highly electrophilic and can act as a Lewis acid, promoting several organic transformations (Batista et al, 1997;Kobayashi et al, 2000;Constantino et al, 2001Constantino et al, , 2004Constantino et al, , 2005Constantino et al, , 2007Andrade, 2004;da Silva-Filho et al, 2005Andrade & Rocha, 2006;Wang et al, 2007;Polo et al, 2008;Cai et al, 2010;Hou et al, 2010Hou et al, , 2011Lacerda et al, 2012;Liu et al, 2013;Martins et al, 2013;dos Santos et al, 2013;Bian et al, 2014;Nasseri et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

Efficient one-pot synthesis of 14-aryl-14H-dibenzo[a,j]xanthene derivatives promoted by niobium pentachloride

2014

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A novel and reusable magnetic nanocatalyst developed based on graphene oxide incorporated strontium nanoparticles for the facial synthesis of β‐enamino ketones under solvent‐free conditions

Mousavi

Sereshti

Nodeh

et al. 2018

Applied Organom Chemis

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A novel magnetic SrFeGO nanocatalyst (NC) was synthesized through a simple sol-gel technique by introducing strontium and iron oxide nanoparticles onto graphene. The synthesized NC was characterized using FT-IR and FE-SEM. Subsequently, the catalytic activity of SrFeGO was tested in a reaction between β-dicarbonyl compounds and aniline derivatives to gain β-enamino ketone derivatives under solvent-free conditions. It was found that SrFeGO NC is a potential catalyst for the synthesis of β-enamino ketones. The β-enamino ketone produced by such reactions could be isolated in high purity without the need for chromatographic purifications. The newly prepared magnetic graphene oxide nanocomposite could be recovered and reused for numerous times with no significant decrease in efficiency. Moreover, the protocol has the advantages of excellent yielding (up to 98%) in short a reaction time, benefitting an easy workup procedure and being environmentally friendly.

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A general and efficient method for synthesis of enaminones and enamino esters catalyzed by NbCl5 under solvent-free conditions

Cited by 6 publications

References 48 publications

Effect of Bronsted Acids and Bases, and Lewis Acid (Sn²⁺) on the Regiochemistry of the Reaction of Amines with Trifluoromethyl-β-diketones: Reaction of 3-Aminopyrrole to Selectively Produce Regioisomeric 1H-Pyrrolo[3,2-b]pyridines

Effect of Bronsted Acids and Bases, and Lewis Acid (Sn²⁺) on the Regiochemistry of the Reaction of Amines with Trifluoromethyl-β-diketones: Reaction of 3-Aminopyrrole to Selectively Produce Regioisomeric 1H-Pyrrolo[3,2-b]pyridines

Efficient one-pot synthesis of 14-aryl-14H-dibenzo[a,j]xanthene derivatives promoted by niobium pentachloride

A novel and reusable magnetic nanocatalyst developed based on graphene oxide incorporated strontium nanoparticles for the facial synthesis of β‐enamino ketones under solvent‐free conditions

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A general and efficient method for synthesis of enaminones and enamino esters catalyzed by NbCl5 under solvent-free conditions

Cited by 6 publications

References 48 publications

Effect of Bronsted Acids and Bases, and Lewis Acid (Sn2+) on the Regiochemistry of the Reaction of Amines with Trifluoromethyl-β-diketones: Reaction of 3-Aminopyrrole to Selectively Produce Regioisomeric 1H-Pyrrolo[3,2-b]pyridines

Effect of Bronsted Acids and Bases, and Lewis Acid (Sn2+) on the Regiochemistry of the Reaction of Amines with Trifluoromethyl-β-diketones: Reaction of 3-Aminopyrrole to Selectively Produce Regioisomeric 1H-Pyrrolo[3,2-b]pyridines

Efficient one-pot synthesis of 14-aryl-14H-dibenzo[a,j]xanthene derivatives promoted by niobium pentachloride

A novel and reusable magnetic nanocatalyst developed based on graphene oxide incorporated strontium nanoparticles for the facial synthesis of β‐enamino ketones under solvent‐free conditions

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Effect of Bronsted Acids and Bases, and Lewis Acid (Sn²⁺) on the Regiochemistry of the Reaction of Amines with Trifluoromethyl-β-diketones: Reaction of 3-Aminopyrrole to Selectively Produce Regioisomeric 1H-Pyrrolo[3,2-b]pyridines

Effect of Bronsted Acids and Bases, and Lewis Acid (Sn²⁺) on the Regiochemistry of the Reaction of Amines with Trifluoromethyl-β-diketones: Reaction of 3-Aminopyrrole to Selectively Produce Regioisomeric 1H-Pyrrolo[3,2-b]pyridines