- Triphenylphosphine Oxide-Catalyzed Selective α,β-Reduction of Conjugated Polyunsaturated Ketones
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The scope of the triphenylphosphine oxide-catalyzed reduction of conjugated polyunsaturated ketones using trichlorosilane as the reducing reagent has been examined. In all cases studied, the α,β-C=C double bond was selectively reduced to a C-C single bond while all other reducible functional groups remained unchanged. This reaction was applied to a large variety of conjugated dienones, a trienone, and a tetraenone. Additionally, a tandem one-pot Wittig/conjugate-reduction reaction sequence was developed to produce γ,δ-unsaturated ketones directly from simple building blocks. In these reactions the byproduct of the Wittig reaction served as the catalyst for the reduction reaction. This strategy was then used in the synthesis of naturally occurring moth pheromones to demonstrate its utility in the context of natural-product synthesis.
- Xia, Xuanshu,Lao, Zhiqi,Toy, Patrick H.
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p. 1100 - 1104
(2019/05/24)
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- Iron-catalyzed aerobic oxidation of allylic alcohols: The issue of C=C bond isomerization
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An aerobic oxidation of allylic alcohols using Fe(NO3) 3·9H2O/TEMPO/NaCl as catalysts under atmospheric pressure of oxygen at room temperature was developed. This eco-friendly and mild protocol provides a convenient pathway to the synthesis of stereodefined α,β-unsaturated enals or enones with the retention of the C-C double-bond configuration.
- Liu, Jinxian,Ma, Shengming
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supporting information
p. 5150 - 5153
(2013/11/06)
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- Synthesis of naturally occurring diene and trienes by Te/Li exchange on (1Z,3Z)-butyltelluro-4-methoxy-1,3-butadiene
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(1Z,3Z)-Butyltelluro-4-methoxy-1,3-butadiene 2 was obtained by the hydrotelluration of (Z)-1-methoxy-but-1-en-3-ynes 1. The butadienyllithium 3 obtained by the Te/Li exchange reaction in the (1Z,3Z)-1-butyltelluro-4-methoxy-1,3-butadiene 2 reacted with aldehydes to form the corresponding alcohols 4a-d with total retention of configuration. The alcohols formed undergo hydrolysis, resulting in the α,β,γ,δ-unsaturated aldehydes of (E,E) configuration, which are precursors of trienes obtained from natural sources. The products of this reaction were employed in the synthesis of methyl-(2E,4E)-decadienoate 7, which is a component of the flavor principles of ripe Bartlett pears. Performing the Wittig reaction of the methyl triphenylphosphorane with the deca-(2E,4E)-dienal 5a, we were able to synthesize the undeca-(1,3E,5E)-triene 6a. This compound is a sex-pheromone component of the marine brown algae Fucus serratus, Dictyopteris plagiograma, and Dictyopteris australis. Performing the Wittig reaction of methyl triphenylphosphorane with the octa-(2E,4E)-dienal 5c, the nona-(1,3E,5E)-triene 6b was synthesized. The compound obtained is a sex-pheromone component of the marine brown alga Sargassum horneri. The octa-(1,3E,5E)-triene 6c was easily obtained from hepta-(2E,4E)-dienal 5d by the Wittig reaction with methyl triphenylphophorane. This compound is a sex-pheromone component of the marine brown alga Fucus serratus.
- Dabdoub, Miguel J.,Dabdoub, Vania B.,Baroni, Adriano C.M.,Hurtado, Gabriela R.,Barbosa, Sandro L.
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experimental part
p. 1666 - 1670
(2010/05/19)
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- Straightforward preparation of (2E,4Z)-2,4-heptadien-1-ol and (2E,4Z)-2,4-heptadienal
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A concise synthesis of (2E,4Z)-2,4-heptadien-1-ol and (2E,4Z)-2,4-heptadienal is presented. Commercially available (Z)-2-penten-1-ol was converted to ethyl-(2E,4Z)-2,4-heptadienoate by reaction with activated MnO2 and (carboethoxymethylene)triphenylphosphorane in the presence of benzoic acid as a catalyst. Ethyl-(2E,4Z)-2,4-hep-tadienoate was converted to (2E,4Z)-2,4-heptadien-1-ol with LiAlH4. The alcohol was partially oxidized to (2E,4Z)-2,4-heptadienal with MnO2. The title compounds are male-specific, antennally active volatile compounds from the Saltcedar leaf beetle, Diorhabda elongata Brulle (Coleoptera: Chrysomelidae) and have potential use in the biological control of the invasive weed saltcedar (Tamarix spp).
- Petroski, Richard J.
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p. 3233 - 3241
(2007/10/03)
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- Synthesis and biological activity of α,β,γ,δ-unsaturated aldehydes from diatoms
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α,β,γ,δ-Unsaturated aldehydes have gained increasing attention since 2,4-decadienal and 2,4,7-decatrienal were isolated from the diatom Thalassiosira rotula and characterized as cell antiproliferative metabolites. Structurally related α,β,γ,δ-unsaturated aldehydes were found in this alga as well as in other diatom species. We present a short and universal synthesis of this compound class along with a structure-activity study of the potential to inhibit sea urchin egg cleavage. Pd0- or CoII-mediated cross coupling of 5-iodo-penta-2,4-dienal with organo-zincates allows the fast and flexible synthesis of numerous aldehydes from this universal precursor. The stereochemistry of the double bond system of the precursor was preserved during the coupling. Bioassays showed that the polarity of the side chain is important for antiproliferative activity with 2,4-decadienal as the most active compound tested compared to the shorter-chain aliphatic homologues and to ω-oxo acids with conjugated double systems. In contrast, the double bond geometry has no influence on biological activity. The α,β-unsaturated 2E-decenal was also highly active, while activity diminished in the case of saturated aldehydes of similar chain length. 1-Decanol, 2-decanone and decanoic acid were not active.
- Adolph, Sven,Poulet, Serge A.,Pohnert, Georg
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p. 3003 - 3008
(2007/10/03)
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- Production of octadienal in the marine diatom Skeletonema costatum
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Marine diatoms produce α,β,γ,δ-unsaturated aldehydes that have detrimental effects on the reproduction of their natural predators. The production of these defensive metabolites is suggested to involve enzymatic oxidation of polyunsaturated fatty acids. In this paper, feeding experiments with labeled precursor provide clear evidence in support of the origin of octadienals 1 and 2 from 6,9,12-hexadecatrienoic acid (5), thus proving the involvement of novel lipoxygenase/lyase activity for the oxidation of C16 fatty acids.
- D'Ippolito, Giuliana,Romano, Giovanna,Caruso, Tonino,Spinella, Aldo,Cimino, Guido,Fontana, Angelo
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p. 885 - 887
(2007/10/03)
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- (2E)-4,4-dimethoxy-2-butenal in the synthesis of conjugated dienes and dienals
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Using (2E)-4,4-dimethoxy-2-butenal as starting compound, methods were developed for synthesis of (2E,4E)-and (2E,4Z)-dimethoxyalkadienes. Deacetalization of the latter gives with high yield the corresponding dienals which are naturally occurring compounds
- Badanyan,Makaryan,Ovanesyan,Panosyan
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p. 633 - 639
(2007/10/03)
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- The preparation and electrocyclic ring-opening of cyclobutenes: Stereocontrolled approaches to substituted conjugated dienes and trienes
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Thermal electrocyclic ring-opening of 4-alkyl-2-cyclobutene-1-carbaldehydes occurs at low temperature to give (2Z,4E)-alkadienals exclusively, and the process is exploited in transforming cis-3-cyclobutene-1,2-dimethanol 1 into a variety of naturally occurring 1,3,5-alkatrienes and 2,4-decadienoates. Desymmetrisation of 1 with Pseudomonas fluorescens lipase gives access to both enantiomers of 3-oxabicyclo[3.2.0]hept-6-en-2-one 4, for use in stereocontrolled routes to 6-oxygenated (2Z,4E)-alkadienals.
- Binns, Falmai,Hayes, Roy,Hodgetts, Kevin J.,Saengchantara, Suthiweth T.,Wallace, Timothy W.,Wallis, Christopher J.
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p. 3631 - 3658
(2007/10/03)
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- Use of cis-3-cyclobutene-1,2-dimethanol in stereoselective routes to some naturally occurring conjugated dienes and trienes
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Thermal electronic ring-opening of 4-alkyl-2-cyclobutene-1-carbaldehydes occurs at low temperature to give (2Z,4E)-alka-2,4-dienals exclusively, and this process is exploited en route to various isomeric naturally occurring 1,3,5-alkatrienes and 2,4-decadienoates from a single precursor, cis-3-cyclobutene-1,2-dimethanol 4.
- Hodgetts, Kevin J.,Saengchantara, Suthiweth T.,Wallis, Christopher J.,Wallace, Timothy W.
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p. 6321 - 6324
(2007/10/02)
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- A Novel and General Route to 1-Iodo-2,4(E,E)-dienes via Pentadienyl Dithiocarbamate
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The title compounds were prepared from pentadienyl dithiocarbamate via S-methylathion and by use of the iodide an unsymmetric, all-trans-conjugated pentaene was synthesized.
- Hayashi, Toshio,Sasaoka, Kazuo,Oishi, Takeshi
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p. 1362 - 1363
(2007/10/02)
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- HIGHLY STEREOCONTOROLLED SYNTHESIS OF (2E,4Z)-DIENIC ESTERS BY ALUMINA CATALYST
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Thermal treatment of β-allenic esters (2) with alumina catalyst in aprotic solvents yielded (2E,4Z)-dienoic esters (3) in 57-87percent yields with 91-100percent stereoselectivity.
- Tsuboi, Sadao,Masuda, Toshihide,Makino, Hiroshi,Takeda, Akira
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p. 209 - 212
(2007/10/02)
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