- PROCESS OF PRODUCTION OF DEHYDROLINALYL ACETATE (II)
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The present invention is related to a novel and improved process for the production of dehydrolinalyl acetate (DLA), which lUPAC name is acetic acid 1 -ethynyl-1,5- dimethyl-hex-4-enyl ester, starting from dehydrolinalool (DLL), which lUPAC name is 3,7-dimethyloct-6-en-1 -yn-3-ol, by acetylation.
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Page/Page column 4-5
(2014/12/09)
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- PROCESS OF PRODUCTION OF DEHYDROLINALYL ACETATE (I)
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The present invention is related to a novel and improved process for the production of dehydrolinalyl acetate (DLA), which IUPAC name is acetic acid 1-ethynyl-1,5- dimethyl-hex-4-enyl ester, starting from dehydrolinalool (DLL), which IUPAC name is 3,7-dimethyloct-6-en-1-yn-3-ol, by catalytic acetylation.
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Page/Page column 5
(2014/12/09)
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- Construction of 1,5-enynes by stereospecific Pd-catalyzed allyl-propargyl cross-couplings
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The palladium-catalyzed cross-coupling of chiral propargyl acetates and allyl boronates delivers chiral 1,5-enynes with excellent levels of chirality transfer and can be applied across a broad range of substrates.
- Ardolino, Michael J.,Morken, James P.
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p. 8770 - 8773
(2012/07/02)
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- ACYLATIONS IN MICRO REACTION SYSTEMS
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A method for acylating tertiary alcohols and phenolic compounds with carboxylic acids or their anhydrides in micro-reaction systems wherein the acylation is effected in the absence of any catalyst including water at residence times of at most 30 minutes.
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Page/Page column 10
(2011/08/04)
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- 2-ALKOXYMETHYL-3-ISOALKENYL-1-METHYLCYCLOPENTENES, USE THEREOF, IN PARTICULAR AS FRAGRANCE SUBSTANCES, CORRESPONDING ARTICLES AND PRODUCTION METHODS
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Compounds of formula (A) are described wherein, independently of one another, the following applies to groups R and R1: R is methyl or ethyl, and R1 is hydrogen or methyl, wherein the meandering line shows that for R1=methyl, the associated double bind is (E)- or (Z)-configured. Furthermore, methods for producing compounds of formula (A) and the use of corresponding compounds as fragrance and/or flavouring substances are described.
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Page/Page column 12
(2009/04/24)
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- Platinum- and gold-catalyzed rearrangement reactions of propargyl acetates: Total syntheses of (-)-α-cubebene, (-)-cubebol, sesquicarene and related terpenes
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Propargyl acetates, in the presence of catalytic amounts of late transition-metal salts such as PtCl2 or AuCl3, represent synthetic equivalents of α-diazoketones. This notion is corroborated by a concise approach to various sesquiterpene natural products starting from readily available substrates. Specifically, (+)-carvomenthone (17) is converted into propargyl acetate (S)-26 by a sequence involving Stille cross-coupling of its kinetic enol triflate 18, regioselective hydroboration/oxidation of the resulting 1,3-diene 19, and addition of an alkynyl cerium reagent to aldehyde 21 thus obtained. Since the latter step was found to be unselective, the configuration of the reacting propargyl acetate was unambiguously set by oxidation followed by diastereoselective transfer hydrogenation by using Noyori's catalyst 25. Compound (5)-26, on treatment with PtCl2 in toluene, converted exclusively to the tricyclic enol acetate 27, which was sap onified to give norcubebone 11 in excellent overall yield. The conversion of this compound into the sesquiterpene alcohol (-)-cubebol (6) was best achieved with MeCeCl2 as the nucleophile, whereas the formation-of the parent hydrocarbon (-)-α-cubebene (4) was effected in excellent yield by recourse to iron-catalyzed cross coupling methodology developed in this laboratory. Since norketone 11 has previously been transformed into (-)-β-cubebene (5) as well as (-)-4-epicubebol 8, our approach constitutes formal total syntheses of these additional natural products as well. Along similar lines, the readily available propargyl acetates 1, 33 and 47 were shown to give access to 2-carene 44, sesquicarene 39, and episesquicarene 51 in excellent overall yields. In this series, however, the cy cloisomerization reaction was best achieved with catalytic amounts of AuCl3 in 1,2-dichloroethane as the solvent. In addition to these preparative results, our data provide some insight into the mechanism of these remarkable skeletal rearrangement reactions. Transformations of this type are likely triggered by initial coordination of the alkyne unit of the substrate to the carbophilic transition-metal cation. Formal attack of the alkene moiety onto the resulting π-complex engenders the formation of an electrophilic cyclopropyl carbene species which subsequently reacts with the adjacent acetate unit to give the final product. The alternative phasing of events, implying initial attack of the acetate (rather than the alkene moiety) onto the metal-alkyne complex, is inconsistent with the stereochemioal data obtained during this total synthesis campaign.
- Fuerstner, Alois,Hannen, Peter
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p. 3006 - 3019
(2008/02/04)
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- 7-endo radical cyclizations catalyzed by titanocene(III). Straightforward synthesis of terpenoids with seven-membered carbocycles
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We describe a novel procedure for the straightforward synthesis of seven-membered carbocycles via free-radical chemistry, based on titanocene(III)-catalyzed 7-endo-dig and 7-endo-trig cyclizations. This procedure has proved to be useful for the chemical preparation of terpenoids with different skeletons containing cycloheptane rings, including the first total syntheses of dauca-4(11),8-diene (2), barekoxide (3), authentic laukarlaol (81), and a valparane diterpenoid (72), as well as a substantially improved synthesis of karahanaenone (1). We also provide theoretical and experimental evidence in support of a plausible mechanism, which may rationalize the preference for the unusual 7-endo cyclization mode shown by radicals with substitution patterns characteristic of the linalyl, nerolidyl, and geranyl linalyl systems. In light of these chemical findings, we discuss the potential involvement of radical cyclizations in the biosynthesis of some terpenoids containing seven-membered carbocycles.
- Justicia, Jose,Oller-Lopez, Juan L.,Campana, Araceli G.,Oltra, J. Enrique,Cuerva, Juan M.,Bunuel, Elena,Cardenas, Diego J.
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p. 14911 - 14921
(2007/10/03)
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- PtCl2-mediated cycloisomerization of unsaturated propargylic carboxylates
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The PtCl2-mediated cycloisomerization of unsaturated propargylic carboxylates yields differently functionalized bicyclo[4.1.0]heptane enol esters from moderate to good yield, in a very diastereoselective manner. We have prepared and submitted to PtCl2-catalyzed cycloisomerization a series of differently substituted hept-1-en-6-ynes with different O-acyl (acetyl, trichloroacetyl, 3,4,5-trimethoxybenzoyl, etc.) protecting groups at propargylic positions, investigating also the effect of the geometry at the double bond, as well as the effect of the number of substituents at the alkene moiety. As a result, we have found that the O-acetyl migrating group is the best one in terms of simplicity and chemical yields. In this reaction we have isolated mixtures of compounds formed by minor 1-acetoxy-allenes and major bicyclo[4.1.0]heptane derivatives. Major products are the result of a sequential process involving steps of cycloisomerization plus cyclopropanation, followed by acyl migration. The basic methanolysis (K2CO3, MeOH) of these intermediates gave mixtures of cis and trans-caran-2-ones. This two-step protocol (cycloisomerization plus basic methanolysis) for the syntheses of α,β-unsaturated cyclopropyl ketones constitutes a synthetic alternative to the usual unfriendly, intramolecular cyclopropanation of unsaturated α-diazocarbonyl derivatives. The formation of these bicyclo[4.1.0]heptane derivatives is a simple, but efficient entry into the skeleton of the 'carane' family of natural products.
- Anjum, Shazia,Marco-Contelles, José
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p. 4793 - 4803
(2007/10/03)
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