N-Heterocyclic carbene-catalyzed [3 + 3] cyclocondensation of bromoenals with hydrazones: highly enantioselective synthesis of dihydropyridazones

Zhang, Chun-Lin; Wang, Dong-Ling; Chen, Kun‐Quan; Song, Ye

doi:10.1039/c5ob01748c

Cited by 35 publications

(6 citation statements)

References 56 publications

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“…Employing aminoindanol‐derived triazolium salts XIIa as the carbene precursor, DIPEA as the base and simple enals 43 in the presence of quinone 57 as an oxidant, led the isolation of the corresponding 4,5‐dihydropyridazones ( S )‐ 58 a in good yields and high enantioselectivities (Scheme ) . Comparable results were obtained performing the reaction with α‐bromoenals 59 under similar conditions and without the need of oxidant …”

Section: Hydrazones As Nucleophilesmentioning

confidence: 94%

“…[35] Comparable resultsw ere obtained performing the reaction with a-bromoenals 59 under similar conditions and without the need of oxidant. [36] Ap lausible mechanism for these processes is depicted in The asymmetrica llylic alkylation of Morita-Baylis-Hillman (MBH) adducts (S N 2'-S N 2'-type reaction) represents ap owerful tool for the construction of chiral buildingb locks. The group of Shi first described the use of hydrazones as versatile nucleophiles for this reaction.…”

Section: Conjugate Addition Of N-monosubstituted Hydrazones To Ab-unmentioning

confidence: 99%

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Hydrazones as Singular Reagents in Asymmetric Organocatalysis

Retamosa

Matador

Monge

et al. 2016

Chemistry A European J

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This Minireview summarizes strategies and developments regarding the use of hydrazones as reagents in asymmetric organocatalysis, their distinct roles in nucleophileelectrophile reactions, cycloadditions and cyclizations. The key structural elements governing the reactivity of these reagents in a preferred pathway will be discussed, as well as their different interactions with organocatalysts, leading to diverse activation modes. Along these studies, the synthetic equivalence of Nmonoalkyl-, N,N-dialkyl-and N-acyl hydrazones with several synthons is also highlighted. Emphasis is also put on the mechanistic studies performed to understand the observed reactivities. Finally, the functional group transformations performed from the available products has also been analysed, highlighting the synthetic value of these methodologies, which served to access numerous families of valuable multifunctional compounds and nitrogen-containing heterocycles.

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Section: Hydrazones As Nucleophilesmentioning

confidence: 94%

Section: Conjugate Addition Of N-monosubstituted Hydrazones To Ab-unmentioning

confidence: 99%

Hydrazones as Singular Reagents in Asymmetric Organocatalysis

Retamosa

Matador

Monge

et al. 2016

Chemistry A European J

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“…In 2015, Ye et al developed an NHC-catalyzed cyclocondensation to provide an enantioselective synthesis of 4,5dihydropyridazones in good yields with high enantioselectivities from 2-bromoenals 1 and hydrazones 14 (Scheme 8). [16] Both β-aryl 2-bromoenals with electron-rich and electron-deficient substituents reacted smoothly with hydrazones access to the cycloadducts 15. Although, alkyl bromoenals were not effective in promoting this transformation.…”

Section: Nhc-catalyzed Synthesis Of N-heterocyclesmentioning

confidence: 99%

NHC‐Catalyzed Enantioselective Transformations Involving α‐Bromoenals

Doraghi,

Ameli,

Ansariashlaghi

et al. 2024

The Chemical Record

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Abstractα‐Haloenals, especially, α‐bromoenals considered as one of the important building blocks in organic synthesis. They can participate in various (3+2)‐, (3+3)‐, (3+4)‐, and (2+4)‐annulation reactions with other organic molecules in the presence of an NHC catalyst to produce enantioenriched carbo‐, and heterocyclic compounds. Herein, we have described NHC‐catalyzed enantioselective transformations of α‐bromoenals in the synthesis of various heterocycles, and carbocycles, as well as acyclic organic compounds.

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“…In addition to the oxidative method, an alternative synthetic approach to chiral 4,5-dihydropyridazin-3-one derivatives was offered by another asymmetric [3+3] cycloaddition of bromoenals and hydrazones catalyzed by an N-heterocyclic carbene. 13 The application of bromoenals delivered the Breslow intermediate, which released bromide to generate electrophilic acylazolium salts that underwent subsequent Michael addition with hydrazones and further reaction sequences to furnish formal [3+3]-cycloaddition adducts.…”

Section: Scheme 6 Enantioselective Oxidative Annulation Between αβ-Unsaturated Aldehydes and Hydrazonesmentioning

confidence: 99%

Asymmetric [3+3] Cycloaddition for Heterocycle Synthesis

Deng

Cheng

Doyle

2017

Synlett

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Asymmetric syntheses of six-membered ring heterocycles are important research targets not only in synthetic organic chemistry but also in pharmaceuticals. The [3+3]-cycloaddition methodology is a complementary strategy to [4+2] cycloaddition for the synthesis of heterocyclic compounds. Recent progress in [3+3]-cycloaddition processes provide powerful asymmetric methodologies for the construction of six-membered ring heterocycles with one to three heteroatoms in the ring. In this account, synthetic efforts during the past five years toward the synthesis of enantioenriched six-membered ring heterocycles through asymmetric [3+3] cycloaddition are reported. Asymmetric organocatalysis uses chiral amines, thioureas, phosphoric acids, or NHC catalysis to achieve high enantiocontrol. Transition-metal catalysts used as chiral Lewis acids to activate a dipolar species is an alternative approach. The most recent advance, chiral transition-metal-catalyzed reactions of enoldiazo compounds, has contributed toward the versatile and highly selective synthesis of six-membered heterocyclic compounds.1 Introduction2 Asymmetric Formal [3+3]-Cycloaddition Reactions by Organocatalysis2.1 By Amino-Catalysis2.2 By N-Heterocyclic Carbenes2.3 By Bifunctional Tertiary Amine-thioureas2.4 By Chiral Phosphoric Acids3 Asymmetric Formal [3+3]-Cycloaddition Reactions by Transition-Metal Catalysis3.1 Copper Catalysis3.2 Other Transition-Metal Catalysis4 Asymmetric [3+3]-Cycloaddition Reactions of Enoldiazo Compounds4.1 Asymmetric [3+3]-Cycloaddition Reactions of Nitrones with Electrophilic Metallo-enolcarbene Intermediates4.2 Dearomatization in Asymmetric [3+3]-Cycloaddition Reactions of Enoldiazoacetates4.3 Asymmetric Stepwise [3+3]-Cycloaddition Reaction of Enoldiazoacetates with Hydrazones5 Summary and Outlook

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N-Heterocyclic carbene-catalyzed [3 + 3] cyclocondensation of bromoenals with hydrazones: highly enantioselective synthesis of dihydropyridazones

Abstract: The N-heterocyclic carbene-catalyzed [3 + 3] cyclocondensation of bromoenals and hydrazones is developed to give the corresponding chiral 4,5-dihydropyridazones in good yields with excellent enantioselectivities.

Cited by 35 publications

References 56 publications

Hydrazones as Singular Reagents in Asymmetric Organocatalysis

Hydrazones as Singular Reagents in Asymmetric Organocatalysis

NHC‐Catalyzed Enantioselective Transformations Involving α‐Bromoenals

Asymmetric [3+3] Cycloaddition for Heterocycle Synthesis

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