Enantioselective Synthesis of Planar‐Chiral Carba‐Paracyclophanes: Rhodium‐Catalyzed [2+2+2] Cycloaddition of Cyclic Diynes with Terminal Monoynes

Araki, Tatsuya; Noguchi, Keiichi; Tanaka, Ken

doi:10.1002/ange.201300696

Cited by 19 publications

(2 citation statements)

References 91 publications

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“…[2] These compounds are well studied and described as intermediates in the formation of different organic compounds, such as benzene or pyridine. [3] In contrast to the above transformations, the formation of the analogous heterometallacycles, [4] B and C, by the heterocoupling of a nitrile and an alkyne or a the homocoupling of two nitriles, has been insufficiently investigated. Owing to this lack of knowledge, we were interested in studying the reactions of nitriles with Group 4 metallocenes.…”

Section: Introductionmentioning

confidence: 99%

Unusual Nitrile–Nitrile and Nitrile–Alkyne Coupling of FcCN and FcCCCN

Becker

Strehler

Korb

et al. 2014

Chemistry A European J

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The reactions of the Group 4 metallocene alkyne complexes, [Cp*2M(η2-Me3SiC2SiMe3)] (1 a: M=Ti, 1 b: M=Zr, Cp*=η5-pentamethylcyclopentadienyl), with the ferrocenyl nitriles, Fc-CN and Fc-C≡C-C≡N (Fc=Fe(η5-C5H5)(η5-C5H4)), is described. In case of Fc-C≡N an unusual nitrile–nitrile C-C homocoupling was observed and 1-metalla-2,5-diaza-cyclopenta-2,4-dienes (3 a, b) were obtained. As the first step of the reaction with 1 b, the nitrile was coordinated to give [Cp*2Zr(η2-Me3SiC2SiMe3)(N≡C-Fc)] (2 b). The reactions with the 3-ferrocenyl-2-propyne-nitrile FcC≡C-C≡N lead to an alkyne–nitrile C-C coupling of two substrates and the formation of 1-metalla-2-aza-cyclopenta-2,4-dienes (4 a, b). For M=Zr, the compound is stabilized by dimerization as evidenced by single-crystal X-ray structure analysis. The electrochemical behavior of 3 a, b and 4 a, b was investigated, showing decomposition after oxidation, leading to different redox-active products.

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Section: Introductionmentioning

confidence: 99%

Unusual Nitrile–Nitrile and Nitrile–Alkyne Coupling of FcCN and FcCCCN

Becker

Strehler

Korb

et al. 2014

Chemistry A European J

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“…Chiral metacyclophanes also constitute a key structural component of some pharmaceuticals 28,29 and supramolecular host materials that accept small molecules [30][31][32] . Consequently, the development of methods to stereoselectively construct chiral metacyclophane skeletons has been of growing interest [33][34][35][36][37][38] .…”

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confidence: 99%

Stereospecific ring expansion from orthocyclophanes with central chirality to metacyclophanes with planar chirality

2014

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Carbon-carbon bonds constitute the major framework of organic molecules and carbonhydrogen bonds are abundant in their peripheries. Such nonpolar s-bonds are thermodynamically stable and kinetically inert in general. Nonetheless, selective activation of those ubiquitous bonds may offer a straightforward method to construct and/or functionalize organic skeletons. Herein we describe ring expansion from orthocyclophanes to metacyclophanes occurring upon sequential action of light and a metal catalyst. Formally, specific non-strained carbon-hydrogen and carbon-carbon bonds are cleaved and exchanged without elimination of any leaving groups. Notably, the product is energetically uphill from the starting material, but the endergonic photocyclization step makes it possible to drive the transformation forward. The ring expansion is extended to the stereospecific synthesis of metacyclophanes possessing planar chirality, during which central chirality on a tertiary carbon is transferred to planar chirality.

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A One‐Pot Approach to Phenanthridine Derivatives through Two‐Step Rhodium(I) and Gold(I) Catalysis

Zhu

Chen

et al. 2015

Adv Synth Catal

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An effectiveo ne-pot procedure for the synthesis of phenanthridine derivatives containing N-or O-heterocycles has been developed through at wo-stepr hodium-catalyzed[ 2 + +2+ +2] cycloaddition and gold-catalyzedh eterocyclization under mild conditions.T he substrate scope has been investigated and ap lausible reactionm echanism has been proposed on the basis of control experiments and previousl iterature reports.Keywords: [2+ +2+ +2] cycloaddition;g old catalysis; heterocyclization;o ne-pot procedure;r hodium catalysis Polycyclicc ompounds containingN -a nd O-heterocycles are the core structures in av ariety of pharmacologicala gents and natural alkaloids.[1] Thus far, the development of new synthetic methodso rs trategies for heterocyclic compounds hasbeenavery important area in organic synthesis.[2] Recently,t he synthesiso f substituted or functionalized phenanthridines hasa ttracted much attention sincet hey are the core structural motifsi nm anyb iologically active molecules as shown in Figure 1, andn ew synthetic protocols for these compounds are stillh ighly desirable. [3] Over the past decades,s ynthesis of polycyclic compounds has made significant progress and al arge number of useful andpractical methodshavebeen explored, in which transition metal catalysish as been playing av ery important role.W ith the aid of transition metal catalysis, one can rapidly generate complex molecular structures from easily accessible starting materials under mild reaction conditions.F or example,t he transitionm etal-catalyzed [2+ +2+ +2] cycloaddition reactions of unsaturated compounds are very useful and straightforward methods for constructing polycyclic compounds.[4] Various highly regioselective [2+ +2+ +2] cycloadditions of diynes under Co,N i, Ir, Ru, Au or Rh catalysis have been reported by several groups.[5-10] Furthermore,heterocyclizations of alkynes under transitionm etal catalysis are also practical and straightforward methodst oc onstruct heterocyclic compounds. [11][12][13][14][15][16][17][18] Nowadays,o ne-pot synthesis is becoming an importants trategys incei tc an improve the efficiency of ac hemical reaction. Theo ne-pot reactions combiningt ransitionm etal catalysis ando rganocatalysis leadt om anye legant and effective synthetic protocols. [19,20] On the basis of this strategy,m ultistep chemical transformationsc an be performed sequentially to givec omplexm olecules in as ingle reaction vessel,s ubsequently reducing work-up and purification steps.Recently,t he reactions catalyzed by gold complexes have been exploreds ignificantly.M oreover, some examples about gold-catalyzed cascade reactions and dual-metal catalysisw ith gold ands econd metals have

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Enantioselective Synthesis of Planar‐Chiral Carba‐Paracyclophanes: Rhodium‐Catalyzed [2+2+2] Cycloaddition of Cyclic Diynes with Terminal Monoynes

Cited by 19 publications

References 91 publications

Unusual Nitrile–Nitrile and Nitrile–Alkyne Coupling of FcCN and FcCCCN

Unusual Nitrile–Nitrile and Nitrile–Alkyne Coupling of FcCN and FcCCCN

Stereospecific ring expansion from orthocyclophanes with central chirality to metacyclophanes with planar chirality

A One‐Pot Approach to Phenanthridine Derivatives through Two‐Step Rhodium(I) and Gold(I) Catalysis

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