Synthese und Stereochemie der isomeren Ambrinole

Armour, Albert G.; Büchi, G.; Eschenmoser, Albert; Storni, A.

doi:10.1002/hlca.19590420652

Cited by 28 publications

(11 citation statements)

References 23 publications

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“…Accordingly, enone 12 was subjected to a 1,2-addition with MeLi·LiBr to yield alcohol 18 in 70% yield. 17 After considerable experimentations, a tandem vinylation-Claisen rearrangement reaction sequence following modifications of the protocol reported by Wei 18 was realized for the direct conversion of alcohol 18 into (−)-isoacanthodoral 11 in 65% yield. Thus, the enantioselective total synthesis of (−)-isoacanthodoral was achieved in 7 steps and 18% overall yield from the commercially available starting materials 17 and 16 .…”

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confidence: 99%

Asymmetric Approach toward Chiral Cyclohex-2-enones from Anisoles via an Enantioselective Isomerization by a New Chiral Diamine Catalyst

Lee

Deng

2012

J. Am. Chem. Soc.

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A 3-step asymmetric approach toward the optically active chiral cyclohex-2-enones from anisoles has been developed. The crucial asymmetric induction step is an unprecedented catalytic enantioselective isomerization of β,γ-unsaturated cyclohex-3-en-1-ones to the corresponding α,β-unsaturated chiral enones. This new asymmetric transformation was realized by cooperative iminium-base catalysis with an electronically tunable new organic catalyst. The synthetic utility of this methodology was highlighted by the enantioselective total synthesis of (−)-isoacanthodoral.

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confidence: 99%

Asymmetric Approach toward Chiral Cyclohex-2-enones from Anisoles via an Enantioselective Isomerization by a New Chiral Diamine Catalyst

Lee

Deng

2012

J. Am. Chem. Soc.

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“…-The mixtures of compounds 2 to 9 obtained as described above were combined (850 mg) and separated by chromatography on silica gel (500 g, activity 2, in petroleum ether/ether -9: 1). The following compounds were obtained in order of elution: a) (-)- (S)-2,5,5-Trimethyl-3,4,5,6,7,~O-hexahydronuphthaZene (8):…”

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Formation of Ambergris Odorants from Ambrein under Simulated Natural Conditions

Ohloff

Schulte‐Elte

Müller

1977

Helvetica Chimica Acta

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SummarySinglet oxygen oxygenation of ambrein (1) and subsequent degradation of the primarily formed ally1 hydroperoxides led to the naturally occurring ambergris odorants 2 to 5. The results allowed the postulate that 1 0 2 is an active reagent in the biodegradation of the tricyclic triterpene alcohol 1 in ambergris. Dihydro-y-ionone (3) [3] had already been identified, and besides the tricyclic enol ether (2) [6], and a-ambrinol (4) [7] [8] recently the hitherto unknown ambra aldehyde (5) [5] were found to be typical ambergris odorants. Bicyclic and tricyclic derivatives of this series, under conditions of equal molecular parameters, possess similar odoriferous properties and are related to each other by the 'triaxial rule of odour sensation ' [9-111. Singlet oxygen may be regarded as an active agent in the degradation of ambrein, especially since porphyrins, known to be efficient photosensitizers, have been identified in ambergris [12] [13], and we wished to carry out this process in vitro. We now find that ambrein (1) [3] [14] in toluene solution easily takes up 1 mol equiv. of molecular oxygen in the presence of dinaphthylenethiophen as a photosensitizer and 180

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“…As mentioned in the introduction, compounds 3–8 show chemical structures which are structurally related to the ionone framework. More specifically, the chemical literature indicates that γ ‐dihydroionone 4 is a suitable starting material for the synthesis of γ ‐coronal 3 , ambrinol 6 and homocyclogeraniol isomers . In spite of this fact, there is still no easy synthesis of γ ‐dihydroionone, especially in enantio‐enriched form, thus limiting access to the aforementioned amber components.…”

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confidence: 99%

“…Concerning the exploitation of enantio‐enriched 4 , we first checked some of the known procedures of acid‐mediated cyclization of γ ‐dihydroionone to give the ambrinol isomers. We found (Scheme ) that the use of H 2 SO 4 in water–THF gives the best results both in terms of overall conversion and of amount of side products formed.…”

Section: Resultsmentioning

confidence: 99%

An expedient preparation of enantio‐enriched ambergris odorants starting from commercial ionone alpha

Serra

2012

Flavour & Fragrance J

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We report the enantioselective synthesis of the ambergris odorants (+)‐(S)‐γ‐ionone, (+)‐(S)‐γ‐dihydroionone, (−)‐α‐ambrinol, (+)‐(S)‐γ‐coronal, (−)‐(S)‐γ‐homocyclogeranyl chloride and (+)‐(S)‐γ‐homocyclogeraniol. At first, the enantio‐enriched (4R,6S)‐4‐acetoxy‐γ‐ionone was prepared starting from commercial racemic ionone alpha by means of a chemo‐enzymatic process. This chiral building block was then converted into (S)‐γ‐dihydroionone which was used as the starting material for the synthesis of the aforementioned odorants. Copyright © 2012 John Wiley & Sons, Ltd.

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Synthese und Stereochemie der isomeren Ambrinole

Abstract: a) Es ist eine Reaktionsfolge entwickelt worden, welche in einem Zuge die Darstellung sämtlicher Struktur‐ und stereoisomeren Ambrinole [Δ8(bzw. Δ9 und Δ1,9)–2,5,5‐Trimethyl‐2‐hydroxy‐octaline] erlaubt.

Cited by 28 publications

References 23 publications

Asymmetric Approach toward Chiral Cyclohex-2-enones from Anisoles via an Enantioselective Isomerization by a New Chiral Diamine Catalyst

Asymmetric Approach toward Chiral Cyclohex-2-enones from Anisoles via an Enantioselective Isomerization by a New Chiral Diamine Catalyst

Formation of Ambergris Odorants from Ambrein under Simulated Natural Conditions

An expedient preparation of enantio‐enriched ambergris odorants starting from commercial ionone alpha

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