Organocatalytic asymmetric multicomponent reactions of aromatic aldehydes and anilines with β-ketoesters: facile and atom-economical access to chiral tetrahydropyridines

Li, Xuejian; Zhao, Yanyan; Qu, Haijun; Mao, Zhenjun; Lin, Xufeng

doi:10.1039/c2cc38349g

Cited by 78 publications

(14 citation statements)

References 49 publications

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“…Ethyl acetoacetate 13 68 194-198 196-198 [100] 12. Methyl acetoacetate 14 72 218-220 214-220 [108] Reaction conditions:Aromatic aldehyde (2 mmol), Aromatic amine (2 mmol) and alkyl acetoacetate (1 mmol), 10 mg LFO (700°C), EtOH (4 ml), Stirring at R.T [a] Isolated yield.…”

Section: Mechanistic Evaluationmentioning

confidence: 99%

Autocombustion‐Promoted Synthesis of Lanthanum Iron Oxide: Application as Heterogeneous Catalyst for Synthesis of Piperidines, Substituted Amines and Light‐Assisted Degradations

Pratibha

Rajput

2020

ChemistrySelect

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An autocombustion technique was adopted to synthesize the Perovskite structured Lanthanum iron oxide nanoparticles (LaFeO3, abbreviated as LFO NPs). This technique offered lots of benefits such as short reaction time along with quick heating rate. LFO NPs were fabricated at different calcination temperatures (300‐800 °C) through the aid of sucrose as chelating agent. The prepared LFO NPs were well characterized by various techniques like X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FT‐IR), Vibrating sample magnetometer (VSM), Ultraviolet‐Visible spectroscopy (UV‐Vis), Brunauer–Emmett–Teller (BET), X‐ray Photo‐Electron Spectroscopy (XPS) and Transmission electron microscopy (TEM) which affirmed that highly crystalline LFO NPs were obtained at 700 °C. Subsequently, the catalytic activity of the LFO NPs was surveyed for three independent approaches: (i) for the synthesis of functionalized piperidines through activation of carbonyl groups in the reacting partners (ii) for the sunlight‐assisted mineralization of health hazardous food colorant, Allura Red AC (iii) for the hydrogenation of nitro aromatic compounds (NACs) using NaBH4 (sodium borohydride) as source of hydrogen in aqueous medium at room temperature.

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Section: Mechanistic Evaluationmentioning

confidence: 99%

Autocombustion‐Promoted Synthesis of Lanthanum Iron Oxide: Application as Heterogeneous Catalyst for Synthesis of Piperidines, Substituted Amines and Light‐Assisted Degradations

Pratibha

Rajput

2020

ChemistrySelect

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“…Dabei stachen zunächst drei sehr unterschiedliche Verfahren zur enantioselektiven Herstellung chiraler Tetrahydropyridine besonders hervor. Lin und Mitarbeiter berichteten über eine elegante asymmetrische Pseudo‐Fünfkomponentensynthese aus aromatischen Aldehyden, Anilinen und β‐Ketoestern, die von spirocyclischen chiralen Phosphorsäuren katalysiert wird (Abbildung 6) 17…”

Section: Heterocyclenunclassified

Chemical Exchange Saturation Transfer (CEST) Agents: Quantum Chemistry and MRI

Feng

Zhu

et al. 2015

Chemistry A European J

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Diamagnetic chemical exchange saturation transfer (CEST) contrast agents offer an alternative to Gd3+-based contrast agents for MRI. They are characterized by containing protons that can rapidly exchange with water and it is advantageous to have these protons resonate in a spectral window that is far removed from water. Here, we report the first results of DFT calculations of the 1H nuclear magnetic shieldings in 41 CEST agents, finding that the experimental shifts can be well predicted (R2 = 0.882). We tested a subset of compounds with the best MRI properties for toxicity and for activity as uncouplers, then obtained mice kidney CEST MRI images for three of the most promising leads finding 16 (2,4-dihydroxybenzoic acid) to be one of the most promising CEST MRI contrast agents to date. Overall, the results are of interest since they show that 1H NMR shifts for CEST agents—charged species—can be well predicted, and that several leads have low toxicity and yield good in vivo MR images.

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“…A solution of NaBH(OAc) 3 and acetic acid in ethanol provide mild and convenient conditions for performing the desired protonation and reduction sequence to prepare highly substituted tetrahydropyridines. 10 , 11 This enabled the formation of three new stereogenic centers with excellent diastereoselectivity for both the protonation and the reduction steps (Table 1 ).…”

Section: Piperidines Synthesized From Kinetic Iminium Intermediatesmentioning

confidence: 99%

Convergent Synthesis of Diverse Tetrahydropyridines via Rh(I)-Catalyzed C–H Functionalization Sequences

Mesganaw

Ellman

2014

Org. Process Res. Dev.

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A Rh-catalyzed C–H bond activation/alkenylation/electrocyclization cascade reaction provides diverse 1,2-dihydropyridines from simple and readily available precursors. The reaction can be carried out at low (<1%) Rh-catalyst loadings, and the use of the robust, air-stable Rh precatalyst, [RhCl(cod)]2, enables the cascade reaction to be easily performed on the benchtop. The 1,2-dihydropyridine products serve as extremely versatile synthetic intermediates for further elaboration often without isolation. The addition of electrophiles under kinetic or thermodynamic conditions provides a wide range of iminiums. Subsequent addition of a nucleophile then generates a diverse array of differently substituted piperidine products. Additionally, [3 + 2] and [4 + 2] cycloadditions of the 1,2-dihydropyridine intermediate provides access to bridged bicyclic structures such as tropanes and isoquinuclidines. These concise reaction sequences enable the formation of highly substituted piperidines in synthetically useful yields with excellent diastereoselectivity.

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Organocatalytic asymmetric multicomponent reactions of aromatic aldehydes and anilines with β-ketoesters: facile and atom-economical access to chiral tetrahydropyridines

Cited by 78 publications

References 49 publications

Autocombustion‐Promoted Synthesis of Lanthanum Iron Oxide: Application as Heterogeneous Catalyst for Synthesis of Piperidines, Substituted Amines and Light‐Assisted Degradations

Autocombustion‐Promoted Synthesis of Lanthanum Iron Oxide: Application as Heterogeneous Catalyst for Synthesis of Piperidines, Substituted Amines and Light‐Assisted Degradations

Chemical Exchange Saturation Transfer (CEST) Agents: Quantum Chemistry and MRI

Convergent Synthesis of Diverse Tetrahydropyridines via Rh(I)-Catalyzed C–H Functionalization Sequences

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