Synthesis of Four‐Membered Aza‐Heterocycles through Catalytic [2 + 2] Cycloaddition Reactions Assisted by Metal Complexes

Prieto, Auxiliadora

doi:10.1002/9781119708841.ch3

Cited by 4 publications

(3 citation statements)

References 82 publications

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“…We propose that NiLac I is the result of a formal [2 + 2] cycloaddition between the Ni(II)-iminate and the ketene in a Staudinger-type β-lactam synthesis. These types of transformations are known employing Rh , and Pd, , however, to the best of our knowledge, no example involving Ni has been reported. We believe that this transformation follows the generally accepted stepwise mechanism of the Staudinger β-lactam reaction.…”

Section: Resultsmentioning

confidence: 95%

Structural Evidence for Aromatic Heterocycle N–O Bond Activation via Oxidative Addition

2023

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Many methods report the scission of N−O bonds of aromatic heterocycles and their subsequent functionalization. Oxidative addition is one of the presumed pathways through which aromatic N−O bond activation with transition metals is achieved. We report the first well-defined pathway of (benz)isoxazole's aromatic N−O bond activation through oxidative addition. We also provide control experiments, which show that aromatic N−O bonds may be broken by strong inorganic reductants. These results highlight that N−O bonds are susceptible to both reduction and oxidative addition, which has important implications for catalysis. Exploring the reactivity of one of these complexes toward a series of electrophiles leads to the discovery of a Staudingertype β-lactam synthesis upon the reaction with a ketene. Finally, we demonstrate that the choice of different metal/ligand combinations allows for selective oxidative addition into either C−I bonds or N−O bonds in the presence of the other.

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Section: Resultsmentioning

confidence: 95%

Structural Evidence for Aromatic Heterocycle N–O Bond Activation via Oxidative Addition

2023

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“…We propose that NiLac I is the result of a formal [2+2] cycloaddition between the Ni(II)-iminate and the ketene in a Staudinger-type β-lactam synthesis. These types of transformations are known employing Rh 39,40 and Pd 41,42 , however to the best of our knowledge, no example involving Ni has been reported. We believe that this transformation follows the generally accepted stepwise mechanism 43 of the Staudinger β-lactam reaction.…”

Section: Reactivity Of the Ni(ii) Complexes With Electrophilesmentioning

confidence: 96%

Structural Evidence for Aromatic Heterocycle N–O Bond Activation via Oxidative Addition

Bogdos

Müller

Morandi

2022

Preprint

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Many methods report the scission of the N–O bonds of aromatic heterocycles and their subsequent functionalization. Oxidative addition is one of the presumed pathways through which aromatic N–O bond activation with transition metals is achieved. We report the first well-defined pathway of (benz)isoxazole’s aromatic N–O bond activation through oxidative addition. We also provide control experiments which show that aromatic N–O bonds may be broken by strong inorganic reductants. These results highlight that N–O bonds are susceptible to both reduction and oxidative addition, which has important implications for catalysis. Exploring the reactivity of one of these complexes towards a series or electrophiles led to the discovery of a Staudingertype β-lactam synthesis upon reaction with a ketene. Finally, we demonstrate that choice of different metal/ligand combinations allows for selective oxidative addition into either C–I bonds or N–O bonds in the presence of the other.

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“…In particular, NHC-catalyzed annulations provide a powerful method for carbocycle and heterocycle syntheses. This has led to the synthesis of various cyclic molecules through NHC-catalyzed [2+2], 35–37 [3+ n ] (n = 2, 3, 4) 38–41 and [4+ n ] ( n = 1, 2) 42–44 annulations (Scheme 2).…”

Section: Introductionmentioning

confidence: 99%

A DFT study of NHC-catalyzed reactions of [3+3] annulations of 2-bromoenals and thioamides: mechanisms and regio- and stereoselectivities

Li,

Geng,

Song

et al. 2023

New J. Chem.

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Synthesis of Four‐Membered Aza‐Heterocycles through Catalytic [2 + 2] Cycloaddition Reactions Assisted by Metal Complexes

Cited by 4 publications

References 82 publications

Structural Evidence for Aromatic Heterocycle N–O Bond Activation via Oxidative Addition

Structural Evidence for Aromatic Heterocycle N–O Bond Activation via Oxidative Addition

Structural Evidence for Aromatic Heterocycle N–O Bond Activation via Oxidative Addition

A DFT study of NHC-catalyzed reactions of [3+3] annulations of 2-bromoenals and thioamides: mechanisms and regio- and stereoselectivities

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