Synthetic study on several eremophilane sesquiterpenes using a common intermediate

Hagiwara, Hisahiro; Uda, Hisashi; Kodama, Tsutomu

doi:10.1039/p19800000963

Cited by 55 publications

(28 citation statements)

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“…The a,P-unsaturated ketone 34 was synthesized from 5 u-androsta-l,lCi-dien-3-one (20) in analogy to a published method [41]. This method gave a low yield (< 10%) for the transformation of enone 14 into enone 35, a transformation which was accomplished in 31% overall yield using the method of Hagiwara et al [42] (see Exper. Part).…”

Section: Is)mentioning

confidence: 99%

“…HC1-solution in acetone gave ketone 43 in 80% yield. 42 (214 mg, 0.75 mmol) in THF (10 ml) at -50" under N2 was added a 1~ solution of lithium tri(sec-buty1)hydridoborate in THF (1 ml, 1 mmol). After 1 h at -50", Me1 (228 mg, 1.6 mmol) was added and the mixture was allowed to reach RT.…”

Section: A-androst-16-en-4-one (38)mentioning

confidence: 99%

“…96-98" (from PE), 3/1-Hydroxy-Sa-androst-16-en-4-one (XI). C ' [42]. A solution of the methoxy-ketone X (1.77 g, 5.9 rnmol) in ether (50 ml) was added at RT.…”

Section: Sa-androsta-216-dien-l~-ol (25)mentioning

confidence: 99%

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Structural and Configurational Dependence of the Sensory Process in Steroids

Ohloff

Maurer

Winter

et al. 1983

Helvetica Chimica Acta

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Structural modifications of testosterone and 19‐nortestosterone have led to the synthesis of over 60 androstane and estrane derivatives whose sensory evaluation has allowed molecular parameters to be established for release of a ‘steroid‐type’ scent. Odor perception with O‐containing compounds in both classes has been found to be regioselective. Osmophoric groups at C(3) were found to be the most active and specific. Functionality at C(2) is accompanied to a large extent by anosmic defects, and O‐containing substituents at C(1) and C(4) appear to affect the receptor membrane in exceptional cases. A further characteristic of the ‘steroid‐type’ scent is diastereoselectivity. The odor intensity of axial 2‐ and 3‐hydroxysteroids is far greater than that of the equatorial epimers, and epimeric hydroxy‐groups in the 1‐, 4‐, and 5‐positions lead to almost complete absence of odor. In addition, only steroids with ‘normal’ ring junctions and configuration were found to be odorants, whereas compounds with cis‐junctions between rings A and B, or C and D, were found to be practically inactive, Steroids therefore folow the ‘triaxial rule of odor sensation’. The most remarkable feature of our findings with steroid odorants is enantioselectivity . Whereas with C 19 ‐steroids of the ‘natural’ enantiomeric series the perception threshold is extremely low (<6 ppb), the corresponding ‘unnatural’ enantiomers have been found essentially odorless by a panel of 30 persons. This appears to be the first reported instance of a total enantioselective response to an odorant.

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Section: Is)mentioning

confidence: 99%

Section: A-androst-16-en-4-one (38)mentioning

confidence: 99%

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Structural and Configurational Dependence of the Sensory Process in Steroids

Ohloff

Maurer

Winter

et al. 1983

Helvetica Chimica Acta

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“…Ethylmenthenone (71) that was prepared by oxidation of the ethylation product of methenone (R)-4 was converted by ozonolytic cleavage into the methyl ester of (S)-3-methyl-5-oxoheptanoic acid (72) in the synthesis of the sex pheromone of the peach leafminer (76 Huang-Minlon deoxygenation of 72 was accompanied by saponification of the ester to give (3S)-methylheptanoic acid (73), which was converted as usual to the target 76 through alcohol 74 and tosylate 75.…”

Section: Use Of 12-adducts Of Cyclic αβ-Enone Monoterpenoids and Ormentioning

confidence: 99%

Natural cyclic α, β-enone monoterpenoids in nucleophilic addition reactions

et al. 2006

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“…The a' (kinetic) enolate (2) of the enone undergoes an initial conjugate addition to an activated olefin (3), in which Z has dual character, acting first as an electron-withdrawing group and then as a leaving group, displacement of which forms the cyclopropane ring of the tricyclo-octanone (4) . 4 We have demonstrated that this type of bicycloannulation is successful with vinyl phosphonium salts (3c-e), vinyl sulfones (1 a, 3 b), and nitro-olefins (3a), and Hagiwara et al have reported an analogous reaction of a-bromoacrylic esters, which they have used as the key step in a synthesis of ishwarane (12). Nitro-olefins, in particular, have become increasingly useful in synthesis in recent years (13)(14)(15), and we present herein a full description of our own work with these versatile reagents.…”

Section: Introductionmentioning

confidence: 99%

Nitro-olefin bicycloannulation: one-step synthesis of tricyclo[3.2.1.0^2,7]octan-6-ones from cyclohexenones and of tricyclo[2.2.1.0^2,6]heptan-3-ones from cyclopentenones

Cory¹,

Anderson²,

Bailey³

et al. 1985

Can. J. Chem.

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. Can. J. Chem. 63, 2618Chem. 63, (1985. Nitro-olefins bicycloannulate the a'-enolates of a-cyclohexenones and a-cyclopentenones by initial addition at -7S°C, followed by further reaction in situ in the presence of hexamethylphosphoramide in refluxing tetrahydrofuran to give tricyclor3.2.1 .0Z,7]octan-6-ones and tricyclo[2.2.1 .02.6]heptan-3-ones in a single synthetic step. The reactions with I-nitropropene and with a nitro-olefin having a more complex P-substituent are stereoselective, forming predominantly the tricyclic diastereomer in which the group derived from the P-substituent of the nitro-olefin is syn to the carbonyl bridge. Based on the isolation of intermediates and side products, the mechanism of the bicycloannulation is shown to proceed via sequential kinetically controlled conjugate addition of the enolate to the nitro-olefin at low temperatures, thermodynamically controlled intramolecular Michael addition at higher temperatures to give a bicyclo[2.2.2]octanone intermediate, and hexamethylphosphoramideassisted expulsion of the nitro group as nitrite ion with formation of the cyclopropane ring. For the first time this type of bicycloannulation has been applied to cyclopentenones, and a one-step synthesis of tricyclenone has been carried out to demonstrate the synthetic utility of this new reaction. [Traduit par le journal] Introduction The development of new methodology for the efficient construction of polycyclic systems has long been a major emphasis of research in organic synthesis. Our own contributions to this work have focussed on the discovery of new bicycloannulation reactions, in which tricyclic structures are formed in a single synthetic operation from monocyclic precursors.' In particular, we have reported a series of methods for the bicycloannulation of cyclohexenes (1 b, 2) and cyclohexenones (la, 3) to give tricyclo[3.2.1 .02.7]octanes (1). This tricyclic system is a salient

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Synthetic study on several eremophilane sesquiterpenes using a common intermediate

Cited by 55 publications

References 2 publications

Structural and Configurational Dependence of the Sensory Process in Steroids

Structural and Configurational Dependence of the Sensory Process in Steroids

Natural cyclic α, β-enone monoterpenoids in nucleophilic addition reactions

Nitro-olefin bicycloannulation: one-step synthesis of tricyclo[3.2.1.0^2,7]octan-6-ones from cyclohexenones and of tricyclo[2.2.1.0^2,6]heptan-3-ones from cyclopentenones

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Synthetic study on several eremophilane sesquiterpenes using a common intermediate

Cited by 55 publications

References 2 publications

Structural and Configurational Dependence of the Sensory Process in Steroids

Structural and Configurational Dependence of the Sensory Process in Steroids

Natural cyclic α, β-enone monoterpenoids in nucleophilic addition reactions

Nitro-olefin bicycloannulation: one-step synthesis of tricyclo[3.2.1.02,7]octan-6-ones from cyclohexenones and of tricyclo[2.2.1.02,6]heptan-3-ones from cyclopentenones

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Nitro-olefin bicycloannulation: one-step synthesis of tricyclo[3.2.1.0^2,7]octan-6-ones from cyclohexenones and of tricyclo[2.2.1.0^2,6]heptan-3-ones from cyclopentenones