An efficient synthesis of α-Cuparenone

Ravindranathan, T.; Patil, Sachindra S.; Dhondge, V. D.; Dantale, Shubhada W.

doi:10.1016/0040-4039(96)00345-0

Cited by 17 publications

(6 citation statements)

References 6 publications

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“…Total synthesis of α-cuparenones has been accomplished in a variety of ways, − despite the challenge due to steric congestion created by two contiguous quaternary centers around the cyclopentane ring . However, synthesis or isolation of α-cuparenone-type sesquiterpenes with high oxidation levels, such as enokipodins A−D ( 1 − 4 ), has not yet been reported.…”

Section: Resultsmentioning

confidence: 99%

Antimicrobial Cuparene-Type Sesquiterpenes, Enokipodins C and D, from a Mycelial Culture of Flammulina velutipes

et al. 2001

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Two new cuparene-type sesquiterpenes, enokipodins C (1) and D (2), were isolated from culture medium of an edible mushroom, Flammulina velutipes, along with enokipodins A (3) and B (4). The structures of 1 and 2 were determined using spectroscopic methods (HRMS, (1)H and (13)C, and 2D NMR). The absolute configuration of enokipodin C was determined from the observed (1)H NMR chemical shifts and NOEs in NOESY experiments after conversion into the corresponding esters with the chiral reagent 2-(2'-methoxy-1'-naphthyl)-3,4-dichlorobenzoic acid. All the metabolites showed antimicrobial activity against a fungus, Cladosporium herbarum, and Gram-positive bacteria, Bacillus subtilis and Staphylococcus aureus.

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Section: Resultsmentioning

confidence: 99%

Antimicrobial Cuparene-Type Sesquiterpenes, Enokipodins C and D, from a Mycelial Culture of Flammulina velutipes

et al. 2001

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“…Many multistep methods have previously been developed for the synthesis of compounds such as (±)-α-and (±)-β-cuparenone or (±)-herbertene, but these methods are lengthy, involve hazardous materials, or give low yields. [6][7][8] Our need to develop a practical method involving fewer step and giving higher yields prompted us to investigate an unusual palladiumcatalyzed tandem Heck cyclization. We therefore examined the formation of gem-dimethyl cyclopentenone moieties from 1-bromo-5-methyl-1-arylhexa-1,5-dien-3-ols under palladium-catalyzed Heck reaction conditions (Scheme 9).…”

Section: Scheme 4 a Plausible Mechanism For The Cyclization Reactionmentioning

confidence: 99%

Palladium-Catalyzed Intramolecular Oxidative Heck Cyclization and Its Application toward a Synthesis of (±)-β-Cuparenone Derivatives Supported by Computational Studies

et al. 2013

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A novel and efficient intramolecular oxidative cyclization of substituted homoallylic alcohols to form cyclic keto compounds under palladium-catalyzed conditions is described. The reaction has practical applications in the synthesis of sesquiterpenes. The mechanism of cyclization, the key step in the tandem reaction, was analyzed by using density functional theory calculations.The cyclization of unsaturated substrates by intramolecular Heck reactions promoted by organopalladium complexes is of fundamental importance for the construction of vast array of mono-and polycarbocyclic systems, and is therefore a highly attractive technique for the synthesis of cyclic natural products. 1 Palladium(II) complexes are extremely important in organopalladium chemistry. Palladium(0) complexes are fairly nucleophilic, rather labile, and easily oxidized, usually to the palladium(II) state. The most synthetically useful chemistry of palladium(0) involves the oxidative addition of aryl, vinylic, or allylic halides or triflates to palladium(0); such reactions can be very useful in the synthesis of carbocycles or heterocycles. 2 Our investigations have focused mainly on possible cycloannulations through an intramolecular Heck reaction followed by oxidation of an alcohol group, most significantly from a bromovinyl alcohol. In continuation of these studies, we have examined the corresponding reactions of homoallylic alcohol derivatives and we have inferred the mechanism of this reaction.As part of our ongoing interest in palladium-catalyzed Heck reactions, 3 we developed a new method and we extended it to the synthesis of some precursors of sesquiterpene natural products. In the context of our general interest in the chemistry of β-bromovinyl aldehydes 4 and our exploration of the sequential indium-mediated allylation and palladium-catalyzed cyclization of such compounds, we attempted to develop a general method for the synthesis of 1-bromohexa-1,5-dien-3-ol derivatives 2 that would undergo an intramolecular Heck reaction to form the corresponding fused methyl-substituted cyclopentenone derivatives 3 (Scheme 1). Scheme 1 Synthesis of substituted cyclopentenonesVarious cyclic bromovinyl aldehydes 1.11-1.16 (Table 1) were subjected to an allylation protocol to assess the generality of our method. In all cases, we obtained the corresponding 1-bromohexa-1,5-dien-3-ol derivatives 2 in good-to-excellent yields.Initially, we chose sodium formate as the base for the Heck cyclization reaction. We subsequently examined the effect on the yields of cyclopentenones of other bases, including organic bases such as triethylamine, which was not effective in promoting the reaction. Although many factors could have effects under our reaction conditions, it seemed logical to assume that the yield might be improved by using an inorganic base. We found that inorganic bases such as sodium carbonate, potassium carbonate, or sodium acetate gave the cyclized products in good-to-moderate yield. When we performed the Heck reaction of 2.16 in the presence of thes...

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“…A large number of multistep methods have been developed for the synthesis of (()-Rand (()-β-cuparenone, (()-herbertene, etc., where the synthetic approaches are lengthy, hazardous, or low yielding. [2][3][4][5][6] A single-step synthesis of (()-R-cuparenone has also been reported with an overall yield of 18% of the desired product. 7 In contemplating ways to reduce the steps as well as to keep the yield moderate, we found that one of the potential solutions would be to explore the option of synthesizing the precursors through palladium-catalyzed intramolecular Heck reactions which could be converted to the desired natural product, i.e., (()-β-cuparenone, in one step.…”

mentioning

confidence: 99%

“…As part of our ongoing interest in palladium-catalyzed Heck reactions, we were interested in developing a new methodology and extending it to the synthesis of some of the sesquiterpene natural product precursors. A large number of multistep methods have been developed for the synthesis of (±)-α- and (±)-β-cuparenone, (±)-herbertene, etc., where the synthetic approaches are lengthy, hazardous, or low yielding. − A single-step synthesis of (±)-α-cuparenone has also been reported with an overall yield of 18% of the desired product .…”

mentioning

confidence: 99%

Novel Synthetic Approach Toward (±)-β-Cuparenone via Palladium-Catalyzed Tandem Heck Cyclization of 1-Bromo-5-methyl-1-aryl-hexa-1,5-dien-3-ol Derivatives

Ray

2006

Org. Lett.

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An efficient synthesis of α-Cuparenone

Cited by 17 publications

References 6 publications

Antimicrobial Cuparene-Type Sesquiterpenes, Enokipodins C and D, from a Mycelial Culture of Flammulina velutipes

Antimicrobial Cuparene-Type Sesquiterpenes, Enokipodins C and D, from a Mycelial Culture of Flammulina velutipes

Palladium-Catalyzed Intramolecular Oxidative Heck Cyclization and Its Application toward a Synthesis of (±)-β-Cuparenone Derivatives Supported by Computational Studies

Novel Synthetic Approach Toward (±)-β-Cuparenone via Palladium-Catalyzed Tandem Heck Cyclization of 1-Bromo-5-methyl-1-aryl-hexa-1,5-dien-3-ol Derivatives

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