Magnetic after effect and walls in FeTi&amp;lt;inf&amp;gt;2&amp;lt;/inf&amp;gt;S&amp;lt;inf&amp;gt;4&amp;lt;/inf&amp;gt;

Marais, A.; Villers, Gauthier de; Vautier, R.

doi:10.1109/tmag.1981.1061647

Cited by 4 publications

(4 citation statements)

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“…He and coworkers, and the groups of Murai and Takai, independently developed an efficient Rh(I)-catalyzed desymmetrizing silacyclization of benzosilylometallocenes derivatives using axially chiral diphosphine ligands [125,126]. The He group demonstrated that using (S)-TMS-SEGPHOS as chiral ligand, this dehydrogenative process can be applied to a wide range of ferrocene and ruthenocene derivatives with good yields and enantioselectivities (Scheme 41a) [126]. A related Rh(I)-catalyzed enantioselective direct cyclative silylation was reported by Shibata et al using chiral diene ligands.…”

Section: Reactions Initiated By Oxidative Addition Of C --H Bonds At ...mentioning

confidence: 99%

Transition Metal‐Catalyzed Desymmetrizations Based on CH Activation Processes

Vidal

Font

Gulı́as

et al. 2022

Handbook of CH-Functionalization

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The relevance of chiral pharmaceuticals and fine chemicals has encouraged the development of synthetic methods that allow the preparation of these products in enantioselective form. Of the different strategies, those relying on the metal‐catalyzed enantioselective activation of CH bonds are especially appealing, owing to their step and atom economy. This is particularly the case in desymmetrization approaches, because of the simplicity of the reactants, and their intrinsic complexity increase characteristics. This article reviews the current state of the art on transition metal‐catalyzed desymmetrizing functionalizations involving enantiodetermining CH activation steps.

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Section: Reactions Initiated By Oxidative Addition Of C --H Bonds At ...mentioning

confidence: 99%

Transition Metal‐Catalyzed Desymmetrizations Based on CH Activation Processes

Vidal

Font

Gulı́as

et al. 2022

Handbook of CH-Functionalization

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“…Despite considerable achievements made for the direct formation of CÀ X bonds (CÀ N, S, Se, Te, Si, Ge, B) [43][44][45][46][47]55,58,61] of ferrocenes, the direct CÀ O formation of ferrocenes is still notably challenging because of the sensitivity of the phenol analogue hydroxyferrocene [62] or the tendency of oxygen electrophiles. [63] In 2021, Zhang's group has demonstrated the first example of highly monoselective cobalt-catalyzed CÀ H alkoxylation of 9 with alcohols 91 (Scheme 21).…”

Section: Fe and Co Catalysismentioning

confidence: 99%

Recent Advances in Transition‐Metal‐Catalyzed C−H Functionalization of Ferrocene Amides

Mou

Zhao

Sun

2022

Chemistry An Asian Journal

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During the past decades, in synthetic organic chemistry, directing-group-assisted CÀ H functionalization is found to be a key tool for the expedient and site-selective construction of CÀ C and hybrid bonds. Among CÀ H functionalization of ferrocene derivatives, the directed group strategy is undoubtedly the most commonly used method. Compared to the other directing groups, ferrocene amides can be synthesized easily and are now recognized as one of the most efficient tools for the selective functionalization of certain positions because its metal centre permits fine, tuneable and reversible coordination. The family of amide directing groups mainly comprises monodentate and bidentate directing groups, which are categorized on the basis of coordination sites. In this review, various CÀ H bond functionalization reactions of ferrocene using amide directing groups are broadly discussed.

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“…[6,7] Shibata, He, Murai and Takai independently reported the synthesis of planar chiral compounds with moderate to high enantioselectivities by asymmetric C-H silylation of ferrocenes. [8][9][10] Recently, we reported an enantioselective silylation of aryl C-H bonds to form enantioenriched benzoxasilole products with up-to 99% ee. [11] Although these reactions can occur with high enantioselectivity, they are limited to the functionalization of aryl C-H bonds.…”

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confidence: 99%

“…(1) Having identified a simple synthesis of 2a, we sought conditions for the asymmetric, intramolecular silylation (Table 1). Based on previous reports of Rh-catalyzed silylations of C-H bonds, [9][10][11][12] we examined the Rh catalyst derived from [Rh(cod)Cl] 2 and (S)-DTBM-SEGPHOS (L1) with cyclohexene as a hydrogen acceptor [30] at 80 °C (entry 1). The functionalization of cyclopropyl C-H bonds occurred in 2 hours under these conditions, yielding the cyclized product 3a in 93% yield and 83% ee.…”

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confidence: 99%

Rhodium‐Catalyzed Enantioselective Silylation of Cyclopropyl C−H Bonds

Lee

Hartwig

2016

Angewandte Chemie

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We describe an enantioseleclive silylation of cyclopropanes catalyzed by a rhodium precursor and the bisphosphine (S)-DTBM-SEGPHOS. (Hydrido)silyl ethers, generated in situ by the dehydrogenative silylation of cyclopropylmethanols with diethylsilane, undergo asymmetric, intramolecular silylation of cyclopropyl C-H bonds in high yields with high enantiomeric excesses in the presence of the rhodium catalyst. The resulting enantioenriched oxasilolanes are suitable substrates for Tamao-Fleming oxidation to form cyclopropanols with conservation of the ee from the C-H bond silylation. Preliminary mechanistic data suggest that C-H cleavage is likely to be the turnover-limiting and enantioselectivity-determining step. Graphical Abstract(Hydrido)silyl ethers, generated in situ by the dehydrogenative silylation of cyclopropylmethanols with diethylsilane, undergo asymmetric, intramolecular silylation of cyclopropyl C-H bonds in high yields with high enantiomeric excesses in the presence of a rhodium catalyst. The silylation products are suitable substrates for Tamao-Fleming oxidation to form cyclopropanols with conservation of the ee from the C-H bond silylation.Keywords asymmetric catalysis; C-H activation; cyclopropane; rhodium; silylation The functionalization of C-H bonds with boranes and silanes has been studied intensively, due to the high regioselectivity of these processes for sterically accessible C-H bonds and widespread utility of the products. [1,2] However, the development of enantioselective variants of these reactions, particularly enantioselective functionalization of alkyl C-H bonds, has been limited (Scheme 1). [3][4][5] Kuninobu, Murai and Takai reported the Correspondence to: John F. Hartwig, jhartwig@berkeley.edu. Supporting information for this article is given via a link at the end of the document. HHS Public Access Author ManuscriptAuthor Manuscript Author ManuscriptAuthor Manuscript asymmetric silylation of a C-H bond to generate a stereogenic silicon center with up-to 88% enantiomeric excess (ee) (Scheme 1A). [6,7] Shibata, He, Murai and Takai independently reported the synthesis of planar chiral compounds with moderate to high enantioselectivities by asymmetric C-H silylation of ferrocenes. [8][9][10] Recently, we reported an enantioselective silylation of aryl C-H bonds to form enantioenriched benzoxasilole products with up-to 99% ee. [11] Although these reactions can occur with high enantioselectivity, they are limited to the functionalization of aryl C-H bonds. The only published set of enantioselective silylations of alkyl C-H bonds occurs with low ee (37-40% ee) and with limited scope (Scheme 1B). [12] To create the first silylations of alkyl C-H bonds that occur with high enantioselectivity, we investigated systems for the reactions of cyclopropanes. C-H bonds of cyclopropanes are more reactive than sp 3 C-H bonds of unstrained rings or alkyl chains, [13] and the rigid conformation of a cyclopropane could allow for high stereoselectivity. Yu and co-workers reported enantioselective...

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Magnetic after effect and walls in FeTi<inf>2</inf>S<inf>4</inf>

Cited by 4 publications

References 9 publications

Transition Metal‐Catalyzed Desymmetrizations Based on CH Activation Processes

Transition Metal‐Catalyzed Desymmetrizations Based on CH Activation Processes

Recent Advances in Transition‐Metal‐Catalyzed C−H Functionalization of Ferrocene Amides

Rhodium‐Catalyzed Enantioselective Silylation of Cyclopropyl C−H Bonds

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