Synthese polycyclischer Naturstoffe durch intramolekulare doppelte Michael‐Addition

Ihara, Masataka; Fukumoto, Keiichiro

doi:10.1002/ange.19931050707

Cited by 31 publications

(4 citation statements)

References 147 publications

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“…The diastereoselectivity of the addition of (E)-enolates 1b-evaried depending on the size of the ester substituent. Those with methyl esters (1b or 1d) proceeded with a low syn-diastereoselectivity ( Table 2, entries 2 and 6), which was improved by addition of lithium chloride to the reaction mixture ( [10][11][12]. Variable amounts of starting material 2B were recovered from the reactions in the presence of HMPA, which was due to the occurrence of competing γ-deprotonation.…”

Section: Resultsmentioning

confidence: 99%

“…[10] Several formally anionic tandem Michael-Michael additions and related reactions were also studied. [10] Several formally anionic tandem Michael-Michael additions and related reactions were also studied.…”

Section: Introductionmentioning

confidence: 99%

“…The enolate Michael addition is a very attractive reaction with respect to its potential in tandem processes because, at the end of the reaction, another enolate is generated that may enter additional reaction steps. [10] Several formally anionic tandem Michael-Michael additions and related reactions were also studied. We reported initial results on new tandem enolate Michael addition/radical cyclization/oxygenation reactions some time ago.…”

Section: Introductionmentioning

confidence: 99%

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Polyfunctional β‐Dicarbonyl Compounds by Michael Addition Reactions of Ester Enolates to α‐Benzylidene and α‐Alkylidene‐β‐dicarbonyl Compounds

Holan¹,

Pohl²,

Cı́sařová³

et al. 2012

Eur J Org Chem

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The scope and stereoselectivity of the Michael addition of ester enolates to α-benzylidene and α-alkylidene β-dicarbonyl compounds was studied. Most substrates reacted in good to excellent yields. Michael acceptors bearing carboxylic functionalities reacted directly in the β-position, whereas aldol and Michael addition competed with unsaturated ketones. The diastereoselectivity of the process is dependent on the substitution pattern of the Michael acceptor and the [a] 3461 Scheme 4. Michael addition reactions of 4-pentenoates 1a-e to ylidenemalonates 2A-C.Table 2. Results of the Michael addition reactions of 1a-e to malonate acceptors 2A-C. Entry Enolate 2 Solvent T [°C] 3 [%] anti/syn [a]www.eurjoc.org

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Polyfunctional β‐Dicarbonyl Compounds by Michael Addition Reactions of Ester Enolates to α‐Benzylidene and α‐Alkylidene‐β‐dicarbonyl Compounds

Holan¹,

Pohl²,

Cı́sařová³

et al. 2012

Eur J Org Chem

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“…Since the stereochemistry of the methyl cuprate addition to the enone 4 would be crucial to the success of our plan, we undertook a model study (Scheme ). Knowing that Diels−Alder reactions of 2,3-disubstituted acrylates are rather difficult, we considered the Rawal diene 6 (X = NR 2 ), which is more reactive than the Danishefsky diene 6 (X = OMe). − Alternatively, such cyclohexenones might be accessible by intermolecular double Michael addition between a vinylogous amide and an enoate . Indeed, the cyclohexenone 9 could be directly prepared from the enolate of 8 by addition of methyl tiglate (1 equiv) at −78 °C (53%).…”

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A Formal Total Synthesis of Dysidiolide

2000

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[structure] A formal total synthesis of the natural product dysidiolide is described. Starting from a Diels-Alder reaction between an enoate and a Rawal diene, the cyclohexenone 4 was synthesized. A subsequent stereospecific methyl cuprate addition established the desired trans configuration in the cyclohexane 3. Wacker oxidation of the pentenyl side chain to the diketone 17 followed by an intramolecular aldol condensation led to the bicyclic enone 2, a key intermediate in a recently reported synthesis of dysidiolide.

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Highly Functionalized Bicyclo[3.2.1]octane Derivatives from Readily Available 2′-Alkoxytricyclo[3.2.1.02,7]octanes: Building Blocks for Terpenes, Part I

Meijere¹,

Hadjiarapoglou

Noltemeyer

et al. 1998

Eur. J. Org. Chem.

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2′‐Alkoxytricyclo[3.2.1.02,7]octanes 4‐R are obtained in good to excellent yields from methyl 2‐chloro‐2‐cyclopropylideneacetate (3) and the dienolates derived from the 3‐alkoxycyclohex‐2‐enones 1‐R and 2‐R, by a cascade of two consecutive Michael additions and a γ‐elimination. Compounds 4‐R are transformed to the correspondingly substituted bicyclo[3.2.1]octanecarboxylates 5 by treatment with acid. 2′‐Methoxytricyclooctanes 4a−d‐Me are readily deprotonated to give chelation‐stabilized cyclopropyllithium derivatives 6‐Me, which react with electrophiles to yield the 7′‐substituted tricyclo[3.2.1.02,7]octanes 4f−i‐Me (61−66%). By acidic workup of such reaction mixtures, or subsequent treatment of the isolated products 4f−i‐Me with acid, efficient transformation to the correspondingly substituted bicyclo[3.2.1]octanecarboxylates 5 is observed.

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Synthese polycyclischer Naturstoffe durch intramolekulare doppelte Michael‐Addition

Cited by 31 publications

References 147 publications

Polyfunctional β‐Dicarbonyl Compounds by Michael Addition Reactions of Ester Enolates to α‐Benzylidene and α‐Alkylidene‐β‐dicarbonyl Compounds

Polyfunctional β‐Dicarbonyl Compounds by Michael Addition Reactions of Ester Enolates to α‐Benzylidene and α‐Alkylidene‐β‐dicarbonyl Compounds

A Formal Total Synthesis of Dysidiolide

Highly Functionalized Bicyclo[3.2.1]octane Derivatives from Readily Available 2′-Alkoxytricyclo[3.2.1.02,7]octanes: Building Blocks for Terpenes, Part I

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