Oxidative Asymmetric [2 + 3] Annulation of Aldehydes with Azomethine Imines Enabled by<i>N</i>-Heterocyclic Carbene Catalysis

Yuan, Shiru; Luo, Yi; Peng, Jingyi; Miao, Maozhong; Xu, Jianfeng; Ren, Hongjun

doi:10.1021/acs.orglett.7b02948

Cited by 51 publications

(24 citation statements)

References 62 publications

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“…Recently, Xu and Ren et. al ., reported an NHC catalysed cycloaddition of aldehydes to azomethine imines, however, their approach suffers from use of excess base and oxidant (Scheme c) . Also Ready et.…”

Section: Methodsmentioning

confidence: 99%

An Aldehyde‐Azomethine Imine [3+2]‐Cycloaddition: High‐Yielding Regioselective Synthesis of Substituted N,N‐Bicyclic Pyrazolidinones

et al. 2018

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Section: Methodsmentioning

confidence: 99%

An Aldehyde‐Azomethine Imine [3+2]‐Cycloaddition: High‐Yielding Regioselective Synthesis of Substituted N,N‐Bicyclic Pyrazolidinones

et al. 2018

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“…Bicyclic pyrazolidinones 65 possessing two vicinal tertiary stereogenic centers was produced in good yields with good diastereo‐ and enantioselectivities by asymmetric [2+3] annulation of aliphatic aldehydes 63 with N , N ′‐cyclic azomethine imines 64 (Scheme 17). [39a] The practical utility of this strategy was exemplified by gram‐scale synthesis of the desired bicyclic pyrazolidinone product in good yield with good diastereo‐ and enantioselectivity. The stereochemical outcome for the product formation can be elucidated by the proposed five‐membered transition state.…”

Section: Figurementioning

confidence: 99%

Recent Advances in N‐Heterocyclic Carbene Catalyzed Oxidative Cyclization for the Formation of Heterocycles

2021

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Oxidative N‐heterocyclic carbene catalyst mediated cyclization proved to be an efficient strategy for the construction of various N‐ and O‐ heterocycles. Among several metal‐free methods available for the construction of heterocyclic compounds, oxidative NHC catalysis proved to be an elegant and efficient strategy as several enantioenriched compounds with excellent enantioselectivities can be synthesized in good yields. The most common method of the generation of these heterocycles proceeds via the commonly encountered intermediate in oxidative NHC catalysis (i. e.) acyl azolium intermediate. This intermediate proves to be the active species as it can undergo reaction with suitable substrates leading to the formation of numerous N‐ and O‐ heterocycles. Herein, recent reports on different strategies that enable formal [2+2], [3+2], [3+3], [4+2] or [4+3] annulations between the incoming substrates and acyl azolium species or other active intermediates which can add to suitable substrate leading to various heterocycles were summarized.

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“…Also in 2015, Ye and co‐workers reported the N‐heterocyclic carbene (NHC)‐catalyzed reaction of α ‐chloroaldehydes with azomethine imines to provide bicyclic pyrazolidinones 3 , with excellent enantiomeric excess obtained in most cases [8a] . A related NHC‐catalyzed oxidative catalytic [3+2] of aldehydes with azomethine imines reported by Ren and co‐workers was also found to be successful with moderate to excellent enantioselectivity (66–98 % ee ) displayed [8b] …”

Section: Introductionmentioning

confidence: 98%

Asymmetric Synthesis of Bicyclic Pyrazolidinones through Alkaloid‐Catalyzed [3+2]‐Cycloadditions of Ketenes and Azomethine Imines

Kerrigan

Mondal

Mitra

et al. 2022

Chemistry A European J

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A versatile asymmetric synthesis of bicyclic pyrazolidinones through alkaloid-catalyzed formal [3 + 2]-and [3 + 2 + 2]-cycloadditions of ketenes with azomethine imines is described. The methodology was found to be tolerant of ketene and a variety of monosubstituted ketenes (R = alkyl, OAc). The products were formed in good to excellent yields (71-99 % for 24 examples, 39 examples in all), with good to excellent diastereoselectivity in many cases (dr 3 : 1 to 27 : 1 for 22 examples), and with excellent enantioselectivity for most examples (� 93 % ee for 34 products). In the case of most disubstituted ketenes, the reaction proceeded through a [3 + 2 + 2]-cycloaddition to form structurally interesting bicyclic pyrazolo-oxadiazepinediones with moderate diastereoselectivity (dr up to 3.7 : 1) and as racemic mixtures (3 examples). The method represents the first unambiguous example of an enantioselective reaction between ketenes and a 1,3-dipole.

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Oxidative Asymmetric [2 + 3] Annulation of Aldehydes with Azomethine Imines Enabled byN-Heterocyclic Carbene Catalysis

Cited by 51 publications

References 62 publications

An Aldehyde‐Azomethine Imine [3+2]‐Cycloaddition: High‐Yielding Regioselective Synthesis of Substituted N,N‐Bicyclic Pyrazolidinones

An Aldehyde‐Azomethine Imine [3+2]‐Cycloaddition: High‐Yielding Regioselective Synthesis of Substituted N,N‐Bicyclic Pyrazolidinones

Recent Advances in N‐Heterocyclic Carbene Catalyzed Oxidative Cyclization for the Formation of Heterocycles

Asymmetric Synthesis of Bicyclic Pyrazolidinones through Alkaloid‐Catalyzed [3+2]‐Cycloadditions of Ketenes and Azomethine Imines

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