Ligand-Controlled Enantioselective [2 + 2] Cycloaddition of Oxabicyclic Alkenes with Terminal Alkynes Using Chiral Iridium Catalysts

Fan, Baomin; Li, Xiao-Jiao; Peng, Fangzhi; Zhang, Hongbin; Chan, Albert S. C.; Shao, Zhihui

doi:10.1021/ol902574c

Cited by 100 publications

(36 citation statements)

References 20 publications

(11 reference statements)

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“…16 Currently, an enantioselective transformation is only known for a Rh( i )-catalyst system with a significant substrate dependence of the enantioselectivity, 17 and an Ir( i )-catalysed reaction which is restricted to benzo oxabicyclic alkenes and terminal alkynes. 18 …”

Section: Introductionmentioning

confidence: 99%

Neutral chiral cyclopentadienyl Ru(ii)Cl catalysts enable enantioselective [2+2]-cycloadditions

Kossler

Cramer

2017

Chem. Sci.

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A chiral version of the Cp*Ru(COD)Cl complex equipped with an atropchiral cyclopentadienyl (Cpx) ligand enables [2+2]-cycloadditions between bicyclic olefins and alkynes with excellent reactivity and enantioselectivity. A streamlined synthesis of the Cpx ligand by a C–H functionalisation approach is shown. The chloride counterion of the neutral CpxRuII complex is essential for enantioselectivity.

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Section: Introductionmentioning

confidence: 99%

Neutral chiral cyclopentadienyl Ru(ii)Cl catalysts enable enantioselective [2+2]-cycloadditions

Kossler

Cramer

2017

Chem. Sci.

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“…[51] Kinetic resolution of racemic bicyclica lkenes has also been demonstrated. [52a] On the basis of mechanism studies,carried out by Fanand coworkers,i tw as proposed that oxidative addition of iridium occurs to generate a[ hydrido(acetylene)iridium(III)] complex.…”

Section: Transition Metal Catalyzed Reactionsmentioning

confidence: 99%

Cyclobutane and Cyclobutene Synthesis: Catalytic Enantioselective [2+2] Cycloadditions

2015

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Cyclobutanes and cyclobutenes are important structural motifs found in numerous biologically significant molecules, and they are useful intermediates for chemical synthesis. Consequently, [2+2] cycloadditions to access cyclobutanes and cyclobutenes have been established to be particularly useful transformations. Within the last 10 years, an increase in the frequency of publications for catalytic enantioselective [2+2] cycloadditions has occurred. These reactions provide access to a wide array of enantiomerically enriched chemical diversity that was not previously attainable. Described in this review are the advances made in catalytic enantioselective [2+2] cycloadditions to access cyclobutanes and cyclobutenes.

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“…Thus, asymmetric reaction of 64 with ketimines 65 provided highly substituted pyrrolidines 66 in 77-99% yields with 99% ee and >20 : 1 dr. Recent representative examples include cycloadditions of alkynes 67 and bicyclic strained alkenes 68 catalyzed by Ir/L34 [66] or Rh/L35 which proceed with good to excellent enantioselectivity [67]. Recent representative examples include cycloadditions of alkynes 67 and bicyclic strained alkenes 68 catalyzed by Ir/L34 [66] or Rh/L35 which proceed with good to excellent enantioselectivity [67].…”

Section: Other Addition Reactionmentioning

confidence: 99%

An Overview of Recent Developments in Metal‐Catalyzed Asymmetric Transformations

Sandoval¹,

Noyori²,

Zhou³

et al. 2012

Organic Chemistry – Breakthroughs and Perspectives

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IntroductionCatalysis is the most efficient means to bring about a chemical transformation, since the catalyst used is in principle not consumed in the process and can continuously catalyze a given process to generate a product. When a metal catalyst is employed, the catalysis itself generally stems from the inherent properties of the given metal(s) -Lewis acidity, variable oxidation states, coordination sphere properties, and so on. For metal-based molecular catalysis, however, the ligand frameworks about the metal center can have a dramatic effect on the stability and catalytic performance, and/or actively participate through metal-ligand cooperative processes. The use of chiral ligands generates a chiral 3D environment that effectively controls the stereo-outcome of the chemical transformation, thus giving rise to asymmetric catalysis. Such strategies have been instrumental in the development of modern synthetic strategies at the academic and industrial levels, and constitute a cornerstone for modern organic syntheses.This chapter aims to give a general overview of the types of metal-catalyzed processes currently possible, with emphasis on the catalytic transformation itself. Only representative examples from the last decade are given to highlight the catalytic process without aiming to be comprehensive [1]. More emphasis is given to C-C bond-forming metal-catalyzed asymmetric syntheses due to the rapid developments in this area in recent years. Mostly intermolecular processes are given as examples and typically the results presented are under optimum conditions and represent the highest efficiency and selectivity obtained. It should be mentioned that a similar chapter using different authors and examples may have been used to illustrate advances in a given area, which is a tribute to the excellence and scope of contemporary research advancing asymmetric catalysis.Contributions where the metal is involved as a (chiral) reagent or systems where enantioselection stems from substrate control or use of chiral auxiliaries were not considered. Catalytically active supramolecular assemblies where metals act as linkers or transformations involving metal-containing enzymes were judged inappropriate. Similarly, selective metal-catalyzed polymerization processes and concurrent breakthroughs in organocatalysis are not included.

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Ligand-Controlled Enantioselective [2 + 2] Cycloaddition of Oxabicyclic Alkenes with Terminal Alkynes Using Chiral Iridium Catalysts

Abstract: The first catalytic asymmetric [2 + 2] cycloaddition of oxabicyclic alkenes and terminal alkynes has been developed. This iridium-catalyzed enantioselective [2 + 2] cycloaddition allows the formation of four stereocenters in a single step with excellent enantioselectivity (94-->99% ee).

Cited by 100 publications

References 20 publications

Neutral chiral cyclopentadienyl Ru(ii)Cl catalysts enable enantioselective [2+2]-cycloadditions

Neutral chiral cyclopentadienyl Ru(ii)Cl catalysts enable enantioselective [2+2]-cycloadditions

Cyclobutane and Cyclobutene Synthesis: Catalytic Enantioselective [2+2] Cycloadditions

An Overview of Recent Developments in Metal‐Catalyzed Asymmetric Transformations

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