Tandem photochemical synthesis of N-amino .beta.-lactams from pyrazolidin-3-ones

Perri, S. T.; Slater, S. C.; Toske, Steven G.; White, James D.

doi:10.1021/jo00311a023

Cited by 38 publications

(7 citation statements)

References 2 publications

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“…[19] The reactions were monitored by thin-layer chromatography on silica plates (silica gel 60 F 254 , Merck) by using UV light and p-anisaldehyde for visualization. Column chromatography was performed on silica gel 60 (0.040-0.063 mm, Merck) with ethyl acetate/cyclohexane as eluent.…”

Section: Methodsmentioning

confidence: 99%

Copper(I) Zeolites as Heterogeneous and Ligand‐Free Catalysts: [3+2] Cycloaddition of Azomethine Imines

Keller

Sido

Pale

et al. 2009

Chemistry A European J

107

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Copper(I)-exchanged zeolites were used as heterogeneous ligand-free catalysts for [3+2] cycloaddition of azomethine ylides, which allows versatile, efficient, and highly regioselective synthesis of pyrazolone derivatives. These cheap and easy-to-prepare catalysts exhibit wide scope and compatibility with functional groups. They are very simple to use, easy to remove (by simple filtration), and recyclable (up to six times without loss of activity).

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Section: Methodsmentioning

confidence: 99%

Copper(I) Zeolites as Heterogeneous and Ligand‐Free Catalysts: [3+2] Cycloaddition of Azomethine Imines

Keller

Sido

Pale

et al. 2009

Chemistry A European J

107

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“…All hydrazines 1a, 1b and hydrazides 1c -1e were prepared by methods reported in the literature [8][9][10][11] as depicted in Scheme 2. For catalysts 1a and 1b, we first tried to isolate them in acid-free forms, but all attempts failed because they are prone to immediately suffer from air oxidation under neutral or basic conditions to give only polymeric materials.…”

Section: Resultsmentioning

confidence: 99%

Development of Cyclic Hydrazine and Hydrazide Type Organocatalyst ⎯ Mechanistic Aspects of Cyclic Hydrazine/Hydrazide-Catalyzed Diels-Αlder Reactions

Suzuki¹,

Hirata²,

Takeda³

2009

HETEROCYCLES

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Some hydrazines and hydrazides were prepared and screened for their catalytic efficiencies in Diels-Alder reactions. 1 H-NMR studies and ab initio calculations revealed that catalytic efficiencies of these catalysts are greatly dependent on the release of the catalysts from the Diels-Alder adducts. INTRODUCTION In the early 1970s, two industrial research groups reported the first examples of (S)-proline-catalyzed enantioselective intramolecular aldol reactions. These reactions, so-called Hajos-Parrish-Eder-Sauer-Wiechert reactions, attracted little attention for about 30 years despite their potential values. 1 In the early 2000s, List and coworkers reported (S)-proline-catalyzed intermolecular asymmetric aldol reactions. 2 Thereafter, as well as proline, related five-membered cyclic secondary amine derivatives have also been applied to many reactions that proceed through enamine or iminium ion intermediates. 3 It is well established that a nitrogen atom that is directly bonded to an atom with one or more lone pairs, such as H 2 N-NH 2 and H 2 N-OH, tends to be a stronger nucleophile than would otherwise be expected. The nucleophic enhancement is called "α-heteroatom effect", 4 and such α-nucleophiles seem to be more advantageous as nitrogen-based heterocyclic organocatalysts than simple secondary amine catalysts, but there are not many reported examples. This type of organocatalyst was first reported to promote Diels-Alder reactions efficiently via iminium ions in 2003, 5 and camphor-based chiral hydrazide catalysts were also reported. 6 Recently, we have investigated Biginelli reaction catalyzed by cyclic hydrazine-type organocatalysts as shown in Figure 1, and we have reported that pyrazolidine dihydrochloride 1a could catalyze Biginelli reactions very efficiently under mild conditions. 7 These results promoted us to screen several cyclic hydrazines and hydrazides for their catalytic activities

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“…Removal of the acyl residue from the extraannular nitrogen produces 1-aminoazetidin-2-ones. The suggested mechanism for this tandem photochemical synthesis of b-lactams involves initial removal of the N1 o-nitrobenzyl substituent, followed by ring contraction via a diazabicyclo[2.1.0]pentane intermediate [90]. Highly enantioselective photocyclization in the solid state of 1-alkyl-2-pyridones has been achieved in inclusion crystals with optically active host compounds to give cyclobutene fused b-lactams, which after sequential treatment with ozone and sodium borohydride afford the corresponding monocyclic b-lactams [91].…”

Section: Monocyclic Derivatives J2131mentioning

confidence: 99%

The Chemistry of 2‐Azetidinones (β‐Lactams)

Alcaide¹,

Almendros²,

Luna³

2011

Modern Heterocyclic Chemistry

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The large number of recent reports on b-lactam chemistry demonstrates the increasing interest in this important class of compounds. Monocyclic b-lactams frequently serve as precursors for the synthesis of classical bicyclic b-lactam antibiotics. The cyclic 2-azetidinone skeleton has been extensively used as a template on which to build the heterocyclic structure fused to the four-membered ring, using the chirality and functionalization of the b-lactam nucleus as a stereocontrolling element. The discovery of nonclassical b-lactam antibiotics, such as monobactams and nocardicins, coupled with ever-growing new applications such as enzyme inhibition has triggered a renewed interest in the building of new monocyclic b-lactam derivatives. Besides the utility of b-lactams as biologically active agents, they are used as intermediates in a-and b-amino acid synthesis, as well as building blocks for alkaloids, heterocycles, taxoids and other types of compounds of biological and medicinal interest. Physicochemical Data Computational ChemistryTheoretical studies show that b-lactams are weaker bases, in the gas phase, than acyclic amides [1]. The attenuation of basicity upon cyclization is stronger than that found for cyclic ketones of similar size due to the existence of a negative hyperconjugation effect that is present in b-lactams but not in cyclic ketones. Ab initio calculations indicate that both b-lactams and acyclic amides are oxygen bases, but the gap between the oxygen and nitrogen intrinsic basicities is much smaller in the former due to the aforementioned cyclization effects. This decrease of the oxygen Modern Heterocyclic Chemistry, First Edition. Edited

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Tandem photochemical synthesis of N-amino .beta.-lactams from pyrazolidin-3-ones

Cited by 38 publications

References 2 publications

Copper(I) Zeolites as Heterogeneous and Ligand‐Free Catalysts: [3+2] Cycloaddition of Azomethine Imines

Copper(I) Zeolites as Heterogeneous and Ligand‐Free Catalysts: [3+2] Cycloaddition of Azomethine Imines

Development of Cyclic Hydrazine and Hydrazide Type Organocatalyst ⎯ Mechanistic Aspects of Cyclic Hydrazine/Hydrazide-Catalyzed Diels-Αlder Reactions

The Chemistry of 2‐Azetidinones (β‐Lactams)

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