[2+1]‐Type Cyclopropanation Reactions

Kamimura, Akio

doi:10.1002/9781118778173.ch01

Cited by 13 publications

(6 citation statements)

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“…Cyclopropanes are recognized as an important unit in natural and biologically active compounds, and the formation of cyclopropanes has been of interest in organic synthesis . Cyclopropanation by diazo compounds using organometallic catalysts, Simmons–Smith-type reactions, conjugate addition–substitution reactions, and the Kulinkovic reaction are representative methods for the formation of cyclopropanes.…”

Section: Introductionmentioning

confidence: 99%

Asymmetric Synthesis of Bicyclic Nitrocyclopropanes from Primary Nitro Compounds and Stereoselective Formation of Tetrahydro-2H-cyclopenta[b]furans via Ring Expansion/Cyclization Reaction

et al. 2016

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Optically active bicyclic nitrocyclopropanes are readily prepared from primary chiral nitro compounds, prepared by the conjugate addition of propionaldehyde to a nitro alkene in the presence of proline-derived organocatalysts. The one-step cyclopropanation took place smoothly in a highly stereoselective manner regardless of the stereogenic center adjacent to the allylic unit. Although the allylation reaction catalyzed by BF3·OEt2 provides a mixture of two possible diastereomers, subsequent oxidation of the alcoholic carbon after the formation of nitrocyclopropanes gave diastereomerically pure single products. As a result, separation of the diastereomers during the reaction sequence is unnecessary. Baeyer-Villiger oxidation of the bicyclic nitrocyclopropane ketones followed by enolization resulted in stereoselective formation of a novel cyclopenta[b]furan ring in good yield via ring expansion followed by transannular nucleophilic cyclization.

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Section: Introductionmentioning

confidence: 99%

Asymmetric Synthesis of Bicyclic Nitrocyclopropanes from Primary Nitro Compounds and Stereoselective Formation of Tetrahydro-2H-cyclopenta[b]furans via Ring Expansion/Cyclization Reaction

et al. 2016

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“…The cyclopropane ring strain also allows them to serve as useful 3C components in the construction of larger ring systems . There are several synthetic methods toward accessing cyclopropanes from alkenes, including the transition-metal catalyzed reaction with diazo compounds . This method, most commonly using Rh or Cu catalysis, has proven widely effective.…”

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confidence: 99%

Radical Cation Cyclopropanations via Chromium Photooxidative Catalysis

Sarabia

Ferreira

2017

Org. Lett.

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The chromium photocatalyzed cyclopropanation of diazo reagents with electron rich alkenes is described. The transformation occurs under mild conditions and features specific distinctions from traditional diazo-based cyclopropanations (e.g., avoiding β-hydride elimination, chemoselectivity considerations, etc.). The reaction appears to work most effectively using chromium catalysis, and a number of decorated cyclopropanes can be accessed in generally good yields.

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“…33 The typical synthesis of cyclopropanes using a [2+1] cycloaddition re-action has been well explored using metal catalysis via the formation of a metal carbene intermediate. 40 In 2020, Mancinelli and Wilkerson-Hill introduced a complementary B(C 6 F 5 ) 3 -catalyzed approach for the cyclopropanation reaction of unactivated alkenes using diazo compounds as a reactive carbene synthon (Scheme 11). 41 Scheme 11 Wilkerson-Hill's and our approach for cyclopropanation and cyclopropenation of terminal alkenes and alkynes with -aryl--diazo esters…”

Section: Synthesis Of Carbocyclesmentioning

confidence: 99%

Activation of Diazo Compounds by Fluorinated Triarylborane Catalysts

Pramanik

Melen

2023

Synthesis

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The diverse applicability of diazo compounds as versatile reagents has enlarged the chemical toolbox in organic synthesis. Over the past few decades, transition metal-catalyzed diazo compound activation has ignited the classical synthetic methodology via utilizing highly reactive metal carbenoid species. Many reviews have also appeared in the literature which discloses the advantage and disadvantages of metal-catalyzed activation of the diazo compound. Recently, tris(pentafluorophenyl) borane-mediated diazo activation reactions have reconciled this research area due to the potential for mild, environmentally-friendly, metal-free, non-toxic reaction conditions, and the diverse reactivity patterns of boranes towards diazo compounds. In this review, we have discussed the reactivity of the boron-diazo precursor adduct with compounds using catalytic and stoichiometric halogenated triarylboranes and, the mechanism of N2 release from the diazo reagent. This generates the reactive carbene species as a key intermediate which can further be exploited for O−H, N−H, S‒H, and C−H insertions, azide insertion, carbonate transfer, C‒C and C=C bond forming reactions, [2+2] or [2+4] cascade cyclization reactions, annulation reactions, etc. This review is classified by the following themes: 1. Introduction 2. Diazo Activation Using Stoichiometric Boranes 3. Diazo Activation Using Catalytic B(C6F5)3 4. B(C6F5)3 Catalyzed Diazo Activation Reactions 5. Conclusions

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[2+1]‐Type Cyclopropanation Reactions

Cited by 13 publications

References 377 publications

Asymmetric Synthesis of Bicyclic Nitrocyclopropanes from Primary Nitro Compounds and Stereoselective Formation of Tetrahydro-2H-cyclopenta[b]furans via Ring Expansion/Cyclization Reaction

Asymmetric Synthesis of Bicyclic Nitrocyclopropanes from Primary Nitro Compounds and Stereoselective Formation of Tetrahydro-2H-cyclopenta[b]furans via Ring Expansion/Cyclization Reaction

Radical Cation Cyclopropanations via Chromium Photooxidative Catalysis

Activation of Diazo Compounds by Fluorinated Triarylborane Catalysts

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