Synthesis of Some Resin Acids

Wenkert, Ernest; Afonso, Adriano; Bredenberg, Johan B-son; Kaneko, Chikara; Tahara, Akira

doi:10.1021/ja01064a026

Cited by 75 publications

(39 citation statements)

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“…[46] Resolution of (±)-desoxypodocarpic acid is achieved by treatment with cinchonine alkaloid 237, whereas the epimeric (±)deisopropyldehydroabietic acid is best resolved with the N-methylcinchonium hydroxide salt 360. Scheme 100.…”

Section: Carboxylic Acid Resolution: Cinchonine Saltmentioning

confidence: 99%

Enantioselective Access to Robinson Annulation Products and Michael Adducts as Precursors

2017

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The Robinson annulation is a reaction that has been useful for numerous syntheses since its discovery in 1935, especially in the field of steroid synthesis. The products are usually obtained after three consecutive steps: the formation of an enolate (or derivative), a conjugate addition, and an aldol reaction. Over the years, several methodological improvements have been made for each individual step or alternative routes have been devised to access the Robinson annulation products. The first part of this Review outlines the most relevant developments towards the formation of monocarbonyl-derived Robinson annulation products (MRA products, MRAPs) and activated monocarbonyl-derived Robinson annulation products (AMRA products, AMRAPs). The following sections are then devoted to the diastereoselective and enantioselective synthesis of these products, while the last section describes the enantiomeric resolution of racemic mixtures.

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Section: Carboxylic Acid Resolution: Cinchonine Saltmentioning

confidence: 99%

Enantioselective Access to Robinson Annulation Products and Michael Adducts as Precursors

2017

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“…[46,47] Die Anellierung mit Pyrrolidin (über ein Enamin-Intermediat) war wesentlich effizienter als andere basische Bedingungen, insbesondere fürH ydrindenonsysteme. [46,47] Die Anellierung mit Pyrrolidin (über ein Enamin-Intermediat) war wesentlich effizienter als andere basische Bedingungen, insbesondere fürH ydrindenonsysteme.…”

Section: Aldolcyclisierungunclassified

“…[46] Die Enantiomerentrennung von (AE)-Desoxypodocarpinsäure gelang durch die Umsetzung mit Cinchonin-Alkaloid 237,w ährend die epimere (AE)-Deisopropyldehydroabietinsäure (360)a mb esten als N-Methylcinchoniumhydroxid-Salz aufgetrennt wurde. [46] Die Enantiomerentrennung von (AE)-Desoxypodocarpinsäure gelang durch die Umsetzung mit Cinchonin-Alkaloid 237,w ährend die epimere (AE)-Deisopropyldehydroabietinsäure (360)a mb esten als N-Methylcinchoniumhydroxid-Salz aufgetrennt wurde.…”

Section: Enantiomerentrennung Durch Carbonsäuren:cinchoninsalzunclassified

Enantioselektive Synthese von Robinson‐Anellierungsprodukten und Michael‐Addukten als Vorstufen

Gallier

Martel²,

Dujardin³

2017

Angewandte Chemie

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Die Robinson‐Anellierung hat seit ihrer Entdeckung 1935 in zahlreichen Synthesen Anwendung gefunden, besonders auf dem Gebiet der Steroidsynthese. Die Produkte werden gewöhnlich nach drei aufeinanderfolgenden Stufen erhalten: der Bildung eines Enolats (oder Derivats davon), einer konjugierten Addition und einer Aldolreaktion. Im Laufe der Jahre wurden mehrere methodische Verbesserungen für jede einzelne Stufe vorgenommen oder alternative Synthesewege hin zu Robinson‐Anellierungsprodukten entwickelt. Im ersten Teil dieses Aufsatzes werden die wichtigsten Entwicklungen für die Bildung Monocarbonyl‐abgeleiteter Robinson‐Anellierungsprodukte (MRA‐Produkten, MRAPs) und von einer aktivierten Monocarbonylverbindung abgeleiteter Robinson‐Anellierungsprodukte (AMRA‐Produkten, AMRAPs) erläutert. In den folgenden Abschnitten werden diastereoselektive und enantioselektive Synthesen dieser Produkte beschrieben, und im letzten Abschnitt wird die Racematspaltung von Enantiomerenmischungen dargelegt.

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“…As shown by the p.m.r. spectrum, this material consisted largely of one diastereomer, and, although the stereochemistry was not rigorously established, literature precedent (30) indicated that the newly alkylated center should possess the configuration shown in 13. In any event, this point was not crucial, since the next step of the synthesis involved hydrolysis and decarboxylative removal of the tertiary carbo~nethoxy moiety.…”

Section: [Traduit Par Le Journal]mentioning

confidence: 98%

“…An alternative, direct conversion of the octalone 7 into the keto ester 12 involving base-promoted condensation of the former with dimethyl carbonate was also considered. However, on the basis of literature precedent (30), it was felt that a reaction of this type would result in carbomethoxylation of 7 at C-1 as well as at the desired position (C-3). Indeed, this direction conversion was later attempted (1 lb) and the product, although claimed to be 12, was not obtained crystalline and no criterion of purity was given.…”

Section: [Traduit Par Le Journal]mentioning

confidence: 99%

Total Synthesis of Eremophilane-type Sesquiterpenoids: (±)-Eremophilenolide, (±)-Tetrahydroligularenolide, and (±)-Aristolochene

Piers¹,

Geraghty²

1973

Can. J. Chem.

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The total synthesis of the racemic forms of the eremophilane-type sesquiterpenoids eremophilenolide (21, tetrahydroligularenolide (3). and aristolochene (4) is described. The octalone 7 was converted via an efficient, regioselective route into the keto ester 12, which served as a common synthetic intermediate for the preparation of the three sesquiterpenoids. Successive subjection of 12 t o alkylation, hydrolysis, and decarboxylation afforded the keto acid 14. Hydrogenation of the latter provided both the cis-fused keto acid 20, which was readily converted into (i)-eremophilenolide (2), and the trnr~s-fused keto acid 15, which was similarly transformed into (i)-tetrahydroligularenolide (3). Conversion of 12 into the dithioketal 23, followed by desulfurization and treatment of the resultant olefinic ester 2 5 with excess mcthyllithium, provided the olefinic alcohol 27. Dehydration of the latter yielded (i)-aristolochene (4).La synthese totale des formes rackmiques des sesquiterpCnoi'des erCmophilenolide (2) du type eremophilane, tCtrahydroligularenolide (3) et I'aristolochtne (4) est dCcrite. L'octalone 7 a CtC converti en passant par un chemin regiosklectif efficace en &to-ester 12, qui sert d'intermkdiaire synthktique commun pour la prCparation de trois sesquiterpenoi'des. Lorsque I'on soumet 12 successivement a une alcoylation,

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Synthesis of Some Resin Acids

Cited by 75 publications

References 0 publications

Enantioselective Access to Robinson Annulation Products and Michael Adducts as Precursors

Enantioselective Access to Robinson Annulation Products and Michael Adducts as Precursors

Enantioselektive Synthese von Robinson‐Anellierungsprodukten und Michael‐Addukten als Vorstufen

Total Synthesis of Eremophilane-type Sesquiterpenoids: (±)-Eremophilenolide, (±)-Tetrahydroligularenolide, and (±)-Aristolochene

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