Highly Enantioselective Copper‐Catalyzed Ring Opening of Oxabicyclic Alkenes with Grignard Reagents

Zhang, Wei; Zhu, Shou‐Fei; Qiao, Xiang‐Chen; Zhou, Qi‐Lin

doi:10.1002/asia.200800159

Cited by 61 publications

(18 citation statements)

References 72 publications

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“…Surprisingly, the exact same product was obtained from the attempted copper-catalyzed nucleophilic addition to the oxanorbornene linkage. 9 In this system the dominant pathway for the intermediate allylic carbocation is the observed selective deprotonation product 10 and not the -deprotonation product 11 typically observed in oxanorbornenes that can aromatize (after conversion to the phenol). 10 A conjugate deprotonation pathway was also observed in the copper-catalyzed nucleophilic addition process as well.…”

Section: Resultsmentioning

confidence: 88%

A novel stereoselective [8+2] double cycloaddition route to hydronaphthalene ring systems

Ying

Zhang

Wiget

et al. 2016

Tetrahedron Letters

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Substituted hydronaphthalenes where each of the ten carbons of the two-ring system contains functionality were obtained through a tandem [8+2] cycloaddition and base-catalyzed rearrangement process using dienylfurans and electron-deficient alkynes. If the [8+2] process is conducted under solvent-free conditions the process could be conducted in a single reaction flask without isolation of the chromatographically sensitive [8+2] cycloadducts. A mechanism involving base catalysed alkene positional isomerization followed by disrotatory electrocyclic ring closure was proposed for the key reaction step that converts [8+2] cycloadducts to hydronaphthalenes. The products undergo selective ring opening-isomerization processes upon treatment with Lewis acids.

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Section: Resultsmentioning

confidence: 88%

A novel stereoselective [8+2] double cycloaddition route to hydronaphthalene ring systems

Ying

Zhang

Wiget

et al. 2016

Tetrahedron Letters

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“…[47,48] Tricarbonychromium complexes of phenyl triflates can in principle be obtained from the corresponding phenols by triflate formation followed by complexation or, vice versa, by phenol complexation followed by triflate formation. To examine its suitability for triflate elimination, 10 was treated with lithium diisopropylamide (LDA) in THF at -78°C in the presence of 2,5-dimethylfuran as the trapping reagent.…”

Section: Resultsmentioning

confidence: 99%

Attempts Directed towards the Synthesis of Intermediate (Aryne)chromium Complexes from Aryl Triflates and from (Haloarene)chromium Complexes

Werner

Butenschön

2012

Eur J Org Chem

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The generation of (η6‐aryne)chromium complexes as reactive intermediates was investigated in two ways. Although earlier attempts directed towards triflate eliminations from a variety of tricarbonyl(phenyl triflate)chromium complexes had failed, more electron‐rich phenyl triflate complexes were considered. This was accomplished either by substitution with two methoxy groups in the arene ligand or by replacement of one of the three carbonyl ligands of the tricarbonylchromium complex with triphenylphosphane. However, the attempted elimination still did not take place; in spite of the increased electron densities in the aromatic ligands, anionic thia‐Fries rearrangements were observed in high yields at –78 °C. As an alternative, elimination of lithium fluoride was tested. Tricarbonyl(2‐lithiofluorobenzene)chromium(0) was generated by tin/lithium exchange. After hydrolytic workup, tricarbonyl(fluorobenzene)chromium was obtained as the main product, indicating that the lithiation step had been successful. A dimeric side product provided evidence for the intermediacy of (benzyne)tricarbonylchromium.

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“…这类手性螺环配体因磷原子上更富电子, 因而在钯催化烯丙基醋酸酯或烯丙醇等对醛的极性翻转不对称烯丙基烷基化反应 [40] , 铜催化格氏试剂对氧杂双环烯烃的不对称环氧开环反应 [41] , 镍催化炔对亚胺的还原偶联反应 [42] 等不对称催化反应中给出了很高的对映选择性. 如在镍催化炔对醛亚胺的还原偶联反应中, 磷原子上连有大位阻取代苯基, 如 3,5-二叔丁基-4-甲氧基苯基的手性螺环单齿叔膦配体(R)-26a 主要得到还原偶联产物, 选择性最高达到 14∶1, 对映选择性最高可达到 94% ee [42] (图 13, 式 19).…”

Section: 螺二氢茚骨架手性螺环配体unclassified

Magical Chiral Spiro Ligands

Xie¹,

Zhou²

2014

Acta Chim. Sinica

155

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Transition metal catalyzed asymmetric reaction is a hot issue and a frontier of the research in current organic chemistry. The design and synthesis of new type of efficient chiral ligands and chiral catalysts, esspecially those with novel skeleton is the focus of research in asymmetric catalysis. Since 1990's, chiral ligands based on spiro skeletons have received increasing attention and gradually developed into a new type of chiral ligands with distinctive characteristics. The skeletons of the chiral spiro ligands developed from spiro[4.4]nonane with three chiral stereocenters to spirobiindane and spiro[4.4]nonadiene with only one axial chirality, as well as other types of spiro skeletons. Nowadays, the library of chiral spiro ligands contains a wide range of chiral spiro ligands with different skeletons, including chiral spiro monophosphorus ligands, diphosphine ligands, phosphine-nitrogen ligands, dinitrogen ligands, and etc. Many of these chiral spiro ligands and related catalysts not only have shown high catalytic activity and high enantioselectivity for various asymmetric reactions such as asymmetric hydrogenations, asymmetric carbon-carbon bond forming reactions, and asymmetric carbon-heteroatom bond forming reactions, but also have made the enantiocontrol of many catalytic asymmetric reactions, which are difficult in obtaining high enantioselectivities, more easily and possible. The chiral spiro skeleton has become a 'privileged structure', and chiral spiro ligands and catalysts have been used in the syntheses of different type of chiral compounds including chiral natural products and chiral drugs. The emergence of chiral spiro ligands increased the dynamism of research on finding new chiral ligands and catalysts, and promoted asymmetric synthesis chemistry. Henceforth, the focus of study in chiral spiro ligands will continue to be the development of new chiral spiro ligands and catalysts with high activity and high enantioselectivity. At the same time, the applications of chiral spiro ligands in the new catalytic asymmetric reactions, and in the asymmetric synthesis of bioactive chiral compounds, chiral natural products and chiral drugs will become a new focus of research.

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Highly Enantioselective Copper‐Catalyzed Ring Opening of Oxabicyclic Alkenes with Grignard Reagents

Cited by 61 publications

References 72 publications

A novel stereoselective [8+2] double cycloaddition route to hydronaphthalene ring systems

A novel stereoselective [8+2] double cycloaddition route to hydronaphthalene ring systems

Attempts Directed towards the Synthesis of Intermediate (Aryne)chromium Complexes from Aryl Triflates and from (Haloarene)chromium Complexes

Magical Chiral Spiro Ligands

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