Propriétés philodiéniques d'esters de quelques énolacétates et énoléthers d'acides α‐cétoniques

Monnin, Jacques

doi:10.1002/hlca.19580410720

Cited by 12 publications

(9 citation statements)

References 4 publications

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“…The observation that α,β‐unsaturated carboxylate ligands can be readily incorporated in the binding pocket of our complexes12 led us to focus our first investigation on the Diels–Alder reaction between the cinnamate ion in 6 and 2,3‐dimethylbutadiene ( 2 ). The reaction between cinnamic acid 1 and 2 proceeds readily in solution with toluene at 165 °C to give the corresponding adduct 3 (Scheme ) 13. However, the reaction of 6 with a large excess of 2 in solution with toluene did not occur, even when heated in a sealed glass tube at 210 °C for 24 h 14.…”

Section: Methodsmentioning

confidence: 99%

Diels–Alder Reactivity of Binuclear Complexes with Calixarene‐like Structures

Käss¹,

Gregor²,

Kersting³

2005

Angew Chem Int Ed

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The regioselectivity of the Diels–Alder reaction between ω‐substituted dienoates and unsymmetrical dienophiles can be strictly controlled by “calixarene‐like” metal complexes of type A (see scheme). The reaction of the dienoate coligand in A with acrylonitrile leads to the exclusive formation of the regioisomer adduct I, which is in striking contrast to the low regioselectivity of the background reaction.

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Section: Methodsmentioning

confidence: 99%

Diels–Alder Reactivity of Binuclear Complexes with Calixarene‐like Structures

Käss¹,

Gregor²,

Kersting³

2005

Angew Chem Int Ed

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“…Next 3,4‐dimethylcyclohex‐3‐enylcarbonyl chloride is added, which reacts with the grafted amino groups to form an amide. The 3,4‐dimethylcyclohex‐3‐enylcarbonyl chloride is prepared by the Diels–Alder reaction of 2,3‐dimethyl‐1,3‐butadiene and ethyl acrylate, and conversion of the ester into the acid chloride 12. Next, OsO 4 adds to the double bond in the functionalized support 1 a (→ 1 b ).…”

Section: Methodsmentioning

confidence: 99%

A Heterogeneouscis-Dihydroxylation Catalyst with Stable, Site-Isolated Osmium-Diolate Reaction Centers

et al. 2001

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Osmium tetroxide is by far the most versatile catalyst for cis-dihydroxylation (DH) of double bonds. [1, 2] When homogeneous catalysts are used, free OsO 4 is always present in some step of the catalytic cycle, and the high toxicity and volatility of OsO 4 have hitherto obstructed industrial application. Previous attempts to immobilize OsO 4 used polymers, for example, with coordination of OsO 4 on polyvinylpyridine. [3, 4] However, hydrolysis of the intermediate Os VI diolate complex requires that Os is detached from the polymeric Lewis base, [5] and this implies an inherent liability to Os leaching. Similarly, reports on immobilized alkaloids for asymmetric DH mention that Os leaching necessitates Os supplementation in subsequent runs. [6] In another attempt, OsO 4 was entrapped in polystyrene microspheres, but the mechanism by which OsO 4 is retained within the polymer is not understood. [7] Herein we report a solid with Os VIII type reactivity, and with a persistent bond between Os and the support. Rigorous heterogeneity tests and reactions with 12 olefins substantiate the value of the new Os catalyst.Our approach is rooted in the mechanism of the cisdihydroxylation, which comprises two stages: 1) attack of the Os VIII cis-dioxo complex on the olefin (osmylation), 2) reoxidation of Os VI to Os VIII and hydrolytic release of the diol. Two points are particularly relevant. First, if the hydrolytic conditions are not too drastic, tetrasubstituted olefins are not converted into cis-diols. [8, 9] These olefins are smoothly osmylated to an osmate(vi) ester, but the rate of subsequent hydrolysis is zero (0 % yield for a tetrasubstituted olefin vs. 83 % for a trisubstituted olefin, ref.[8]). Second, an Os VI monodiolate complex can be reoxidized to cis-dioxo Os VIII without release of the diol; subsequent addition of a second olefin results in an Os bisdiolate complex.[10] These two properties make it possible to immobilize a catalytically active Os compound by the addition of OsO 4 to a tetrasubstituted olefin that is covalently linked to a silica support (1 a, Scheme 1). The tetrasubstituted diolate ester (1 b) which is [*] Prof.

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“…3) A [17]. (2) Hydrolysis of the ester, A, to produce 3,4-dimethylcyclohex-3-enyl carboxylic acid, B.…”

Section: Synthesis and Characterisation Of The Os-silsesquioxanementioning

confidence: 99%

Osmium silsesquioxane as model compound and homogeneous catalyst for the dihydroxylation of alkenes

Pescarmona

Masters

Waal

et al. 2004

Journal of Molecular Catalysis A: Chemical

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Propriétés philodiéniques d'esters de quelques énolacétates et énoléthers d'acides α‐cétoniques

Cited by 12 publications

References 4 publications

Diels–Alder Reactivity of Binuclear Complexes with Calixarene‐like Structures

Diels–Alder Reactivity of Binuclear Complexes with Calixarene‐like Structures

A Heterogeneouscis-Dihydroxylation Catalyst with Stable, Site-Isolated Osmium-Diolate Reaction Centers

Osmium silsesquioxane as model compound and homogeneous catalyst for the dihydroxylation of alkenes

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