- Anodic coupling reactions: probing the stereochemistry of tetrahydrofuran formation. A short, convenient synthesis of linalool oxide.
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[reaction: see text]. Intramolecular coupling reactions between enol ether radical cations and oxygen nucleophiles are primarily governed by stereoelectronics. By taking advantage of this observation, a tetrahydrofuran building block for use in constructing (+)-linalool oxide and rotundisine has been synthesized in four steps from a commercially available starting material. The synthesis of (+)-linalool oxide has been completed.
- Duan,Moeller
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- UTL titanosilicate: An extra-large pore epoxidation catalyst with tunable textural properties
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The UTL titanosilicate was prepared together with related lamellar Ti-IPC-1PISi material and zeolites Ti-IPC-2 (OKO) and Ti-IPC-4 (PCR) via top-down synthesis. The titanium can be incorporated to the UTL framework by conventional hydrothermal synthesis and it does not affect the so-called ADOR chemistry of the UTL material. Silica-titania pillaring concept was successfully applied providing very active Ti-IPC-1PITi catalyst for bulky molecules epoxidation with hydrogen peroxide. The textural properties of catalysts prepared can be tuned widely keeping the same crystalline titanosilicate active phase. All the materials were characterised by XRD, nitrogen sorption measurement, SEM, and DR-UV/vis spectroscopy. Ti-IPC-1PITi was the most active catalyst in cyclooctene, norbornene, and linalool epoxidation due to the lowest diffusion constraints and sufficient titanium content. Ti-UTL showed activity similar to Ti-BEA in epoxidation of cyclooctene and it provided different products than other titanosilicates in oxidation of linalool with hydrogen peroxide.
- P?ech, Jan,?ejka, Ji?í
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- VOLATILE OIL CONSTITUENTS OF SAGEBRUSH
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The volatile oil of Artemisia arbuscula arbuscula contained a new irregular monoterpene, 2,5-dimethyl-4-vinyl-1,5-hexadiene-3-ol (isolyratol), which was isolated and identified by spectral means.The optically pure furanoid (2S,5S)-trans-5-methyl-5-vinyltetrahydrofur-2-yl methyl ketone (arbusculone), was also characterized by transformation to known (2S,5S)-trans-linalyl oxide.The former component has never been isolated from natural sources prior to this study.The neutral pentane extract also contained several previously characterized non-head-to-tail monoterpenes including artemiseole, artemisia ketone, artemisyl acetate, methyl santolinate, and santolina triene, as well as the regular monoterpenes 1,8-cineole, camphor, p-cymene, camphene and the C6 fragment, terelactone. - Key Word Index: Artemisia arbuscula arbuscula; Asteraceae (Compositae); volatile oil; monoterpenes; irregular monoterpenes.
- Epstein, William W.,Gaudioso, Larry A.
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- One-pot synthesis at room temperature of epoxides and linalool derivative pyrans in monolacunary Na7PW11O39-catalyzed oxidation reactions by hydrogen peroxide
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In this work, we describe a new one-pot synthesis route of valuable linalool oxidation derivatives (i.e., 2-(5-methyl-5-vinyltetrahydrofuran-2-yl propan-2-ol) (1a)), 2,2,6-trimethyl-6-vinyltetrahydro-2H-pyran-3-ol (1b) and diepoxide (1c), using a green oxidant (i.e., hydrogen peroxide) under mild conditions (i.e., room temperature). Lacunar Keggin heteropolyacid salts were the catalysts investigated in this reaction. Among them, Na7PW11O39 was the most active and selective toward oxidation products. All the catalysts were characterized by FT-IR, TG/DSC, BET, XRD analyses and potentiometric titration. The main reaction parameters were assessed. Special attention was dedicated to correlating the composition and properties of the catalysts and their activity.
- Da Silva, Márcio J.,Teixeira, Milena Galdino,Vilanculo, Castelo B.,Villarreal, Jesus Avendano
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p. 7691 - 7697
(2020/03/10)
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- Enantioselective Bio-Hydrolysis of Geranyl-Derived rac-Epoxides: A Chemoenzymatic Route to trans-Furanoid Linalool Oxide
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In contrast to many chemical dihydroxylation methods, enzymatic epoxide hydrolysis provides an environmentally benign route to vicinal diols, which are important intermediates in the synthesis of fine chemicals and pharmaceuticals. Using epoxide hydrolases, enantiopure diols are accessible under mild conditions. In order to assess the selectivity of epoxide hydrolases on geraniol-derived oxiranes, a range of derivatives were screened against a large variety of enzyme preparations. For nearly all substrates, a matching hydrolase with excellent enantioselectivity (≥95% ee) could be found. In addition, a chemoenzymatic approach for the stereoselective synthesis of furanoid linalool oxide was developed. Combination of enzymatic enantioselective hydrolysis with stereoselective Tsuji-Trost reaction granted diastereoselective access to trans-(2R,5R)-configured linalool oxide with high diastereomeric and enantiomeric excess (97% de and 97% ee). (Figure presented.).
- van Lint, Matthijs J.,Gümüs, Aysegül,Ruijter, Eelco,Faber, Kurt,Orru, Romano V. A.,Hall, Mélanie
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p. 813 - 825
(2019/01/04)
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- A protecting-group-free synthesis of arbusculone, andirolactone, pinnatolide, ipomolactone, cyclocapitelline and isocyclocapitelline
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A general approach for a collective synthesis of natural products containing substituted THF ring is described. In this paper, Arbusculone, a small molecule natural product accomplished using a short route, is used as the key intermediate to achieve the total synthesis of Andirolactone, Pinnatolide, Ipomolactone, Cyclocapitelline, Isocyclocapitelline and their two isomers in less than ten steps. The present effort highlights protecting-group-free total syntheses and the shortest route to access these natural products from commercially available cheap starting materials.
- Gajula, Srinivas,Madhu, Madasu,Chintakrinda, Suresh Kumar,Yadav,Mohapatra, Debendra K.
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p. 4172 - 4175
(2018/10/20)
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- Asymmetric synthesis and structure-activity studies of the fungal metabolites colletorin A, colletochlorin A and their halogenates analogues
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The first asymmetric total synthesis of both enantiomers of the natural products colletorin A and colletochlorin A is presented. The proposed methodology is based on the coupling reaction between highly substituted aromatic Gilman cuprates and optically active allyl bromides, in turn obtained by Sharpless asymmetric dihydroxylation. The latter ensured a high degree of regio- and stereocontrol in the enantioselective step of the synthesis. The same synthetic strategy has been also applied for the preparation of differently halogenated synthetic analogues of colletochlorin A in high enantiomeric purity. The enantioselective synthesis of colletorin A and colletochlorin A allows to reliably assign their absolute configuration. Preliminary assessment of their herbicidal and insecticidal properties evidence the possibility to modulate the bioactivity of these compounds, highlighting its dependence on both the absolute stereochemistry and the halogen nature.
- Marsico, Giulia,Pignataro, Barbara A.,Masi, Marco,Evidente, Antonio,Casella, Francesca,Zonno, Maria Chiara,Tak, Jun-Hyung,Bloomquist, Jeffrey R.,Superchi, Stefano,Scafato, Patrizia
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p. 3912 - 3923
(2018/06/08)
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- Antimalarial Properties of Simplified Kalihinol Analogues
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Several kalihinol natural products, members of the broader isocyanoterpene family of antimalarial agents, are potent inhibitors of Plasmodium falciparum, the agent of the most severe form of human malaria. Our previous total synthesis of kalihinol B provided a blueprint to generate many analogues within this family, some as complex as the natural product and some much simplified and easier to access. Each analogue was tested for blood-stage antimalarial activity using both drug-sensitive and -resistant P. falciparum strains. Many considerably simpler analogues of the kalihinols retained potent activity, as did a compound with a different decalin scaffold made in only three steps from sclareolide. Finally, one representative compound showed reasonable stability toward microsomal metabolism, suggesting that the isonitrile functional group that is critical for activity is not an inherent liability in these compounds.
- Daub, Mary Elisabeth,Prudhomme, Jacques,Ben Mamoun, Choukri,Le Roch, Karine G.,Vanderwal, Christopher D.
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supporting information
p. 355 - 360
(2017/03/17)
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- Catalytic homogeneous oxidation of monoterpenes and cyclooctene with hydrogen peroxide in the presence of sandwich-type tungstophosphates [M4(H2O)2(PW9O34)2]n?, M = CoII, MnII and FeIII
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Catalytic efficiency of tetrabutylammonium salts of sandwich tungstophosphates B‐α‐[M4(H2O)2(PW9O34)2]n?, M = CoII, MnII, FeIII, was studied in the oxidation of (R)-(+)-limonene, geraniol, linalool, linalyl acetate, carveol, and cis-cyclooctene with hydrogen peroxide, in acetonitrile. Oxidation of (R)-(+)-limonene gave limonene-1,2-diol as main product. Epoxidation of linalool takes place preferentially at the more substituted 6,7-double bond, the corresponding 6,7-epoxide reacting further, yielding furano- and pyrano-oxides, via intramolecular cyclization. Oxidation of linalyl acetate occurred preferentially at the more substituted 6,7-double bond for Mn4(PW9)2, affording 6,7-epoxide at 82% selectivity. Linalyl acetate 1,2-epoxide was the major product with 51% and 77% selectivity for Co4(PW9)2 and Fe4(PW9)2, respectively. Oxidation of carveol occurred with very good conversions in the presence of Mn4(PW9)2, Co4(PW9)2 and Fe4(PW9)2, yielding carvone and carveol 1,2-epoxide in similar amounts. Oxidation of cis-cyclooctene gave only the epoxide, while oxidation of geraniol at room temperature afforded 2,3-epoxygeraniol as the major product.
- Santos, Isabel C.M.S.,Gamelas, José A.F.,Duarte, Tiago A.G.,Sim?es, Mário M.Q.,Neves, M. Gra?a P.M.S.,Cavaleiro, José A.S.,Cavaleiro, Ana M.V.
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p. 593 - 599
(2016/12/16)
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- Method for preparing furan-type oxidized linalool
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The invention discloses a method for preparing furan-type oxidized linalool. The method specifically comprises the following steps: firstly, at the room temperature, mixing and stirring 4H-5-(1-hydroxyl-1-methyl ethyl)-2-methyl-2-furan ethanol, paratoluensulfonyl chloride and alkali to implement reaction, after the reaction is completed, adjusting the pH value to be neutral by using an acid solution, extracting, drying and filtering; performing evaporation concentration on the filtrate so as to obtain sulfonate; adding potassium tert-butoxide and tertiary butanol into the sulfonate, and performing reaction at 70-80 DEG C so as to obtain a crude product; and performing purification treatment on the crude product, thereby obtaining the furan-type oxidized linalool. The method disclosed by the invention is easy in raw material obtaining, simple in preparation process, convenient to operate, relatively low in production cost and applicable to industrial production.
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Paragraph 0030-0057
(2017/09/13)
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- Unusually Broad Substrate Profile of Self-Sufficient Cytochrome P450 Monooxygenase CYP116B4 from Labrenzia aggregata
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A new member of the CYP116B subfamily - P450LaMO - was discovered in Labrenzia aggregata by genomic data mining. It was successfully overexpressed in Escherichia coli, purified, and subsequently characterized spectroscopically, and its catalytic properties were assessed. Substrate profiling of the P450LaMO revealed that it was a versatile catalyst, exhibiting hydroxylation and epoxidation activities as well as O-dealkylation and asymmetric sulfoxidation activities. Diverse compounds, including alkylbenzenes, aromatic bicyclic molecules, and terpenoids, were shown to be hydroxylated by P450LaMO. Such diverse catalytic activities are uncommon for the bacterial P450s, and the P450LaMO -mediated stereoselective hydroxylation of inactivated C - H bonds - ubiquitous and relatively unreactive in organic molecules - is particularly unusual. The self-sufficient nature of P450LaMO, coupled with its broad substrate range, highlights it as an ideal template for directed evolution towards various applications.
- Yin, Yue-Cai,Yu, Hui-Lei,Luan, Zheng-Jiao,Li, Ren-Jie,Ouyang, Peng-Fei,Liu, Jing,Xu, Jian-He
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p. 2443 - 2449
(2015/03/03)
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- Unusually Broad Substrate Profile of Self-Sufficient Cytochrome P450 Monooxygenase CYP116B4 from Labrenzia aggregata
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A new member of the CYP116B subfamily - P450LaMO - was discovered in Labrenzia aggregata by genomic data mining. It was successfully overexpressed in Escherichia coli, purified, and subsequently characterized spectroscopically, and its catalytic properties were assessed. Substrate profiling of the P450LaMO revealed that it was a versatile catalyst, exhibiting hydroxylation and epoxidation activities as well as O-dealkylation and asymmetric sulfoxidation activities. Diverse compounds, including alkylbenzenes, aromatic bicyclic molecules, and terpenoids, were shown to be hydroxylated by P450LaMO. Such diverse catalytic activities are uncommon for the bacterial P450s, and the P450LaMO -mediated stereoselective hydroxylation of inactivated C-H bonds - ubiquitous and relatively unreactive in organic molecules - is particularly unusual. The self-sufficient nature of P450LaMO, coupled with its broad substrate range, highlights it as an ideal template for directed evolution towards various applications.
- Yin, Yue-Cai,Yu, Hui-Lei,Luan, Zheng-Jiao,Li, Ren-Jie,Ouyang, Peng-Fei,Liu, Jing,Xu, Jian-He
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p. 2443 - 2449
(2015/08/24)
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- Cis-2,6-Bis-(methanolate)-piperidine oxovanadium(V) complexes as catalysts for oxidative alkenol cyclization by tert-butyl hydroperoxide
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cis-2,6-Bis-(methanolate)-piperidine oxovanadium(V) complexes are Lewis acids able to catalyze oxidative cyclization of alkenols by tert-butyl hydroperoxide (TBHP). Terminal dimethyl-substituted (prenyl-type) 4-pentenols bearing an alkyl or a phenyl group in position 1 afford under such conditions 2,5-cis-derivatives of 2-(tetrahydrofuran-2-yl)-2-propanol as major and tetrahydropyran-3-ols as minor products (four examples). Oxidizing 1-phenyl-6-methylhept-5-en-1-ol yields a 75/25-mixture of the derived 2-(tetrahydropyran-2-yl)-2-propanol and an oxepan-3-ol, whereas 2-propenols give epoxides in up to 94% yield. Epoxidizing geraniol by TBHP in the presence of a vanadium catalyst prepared from (2S,6R)-2-diphenylmethanol-6- hydroxymethylpiperidine occurs enantioselectively. Highfield shifts of vanadium-51 resonances upon adding alkyl hydroperoxides to solutions of cis-2,6-bis-(methanolate)-piperidine vanadium(V) complexes point to vanadium(V) tert-butyl peroxy complex formation as key step for activating peroxides.
- D?nges, Maike,Amberg, Matthias,Stapf, Georg,Kelm, Harald,Bergstr??er, Uwe,Hartung, Jens
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p. 120 - 134
(2014/07/08)
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- Trans-2-tritylcyclohexanol as a chiral auxiliary in permanganate-mediated oxidative cyclization of 2-methylenehept-5-enoates: Application to the synthesis of trans-(+)-linalool oxide
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The permanganate-mediated oxidative cyclization of a series of 2-methylenehept-5-eneoates bearing different chiral auxiliaries was investigated, leading to the discovery of trans-2-tritylcyclohexanol (TTC) as a highly effective chiral controller for the f
- Al Hazmi, Ali M.,Sheikh, Nadeem S.,Bataille, Carole J.R.,Al-Hadedi, Azzam A.M.,Watkin, Sam V.,Luker, Tim J.,Camp, Nicholas P.,Brown, Richard C.D.
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p. 5104 - 5107
(2015/01/08)
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- Biotransformations of terpenes by fungi from amazonian Citrus plants
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The biotransformations of (RS)-linalool (1), (S)-citronellal (2), and sabinene (3) with fungi isolated from the epicarp of fruits of Citrus genus of the Amazonian forest (i.e., C. limon, C. aurantifolia, C. aurantium, and C. paradisiaca) are reported. The
- Moreno Rueda, Maria Gabriela,Guerrini, Alessandra,Giovannini, Pier Paolo,Medici, Alessandro,Grandini, Alessandro,Sacchetti, Gianni,Pedrini, Paola
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p. 1909 - 1919
(2013/11/06)
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- Catalytic performance of a boron peroxotungstate complex under homogeneous and heterogeneous conditions
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The preparation and characterization (FT-IR, FT-Raman, 11B MAS NMR, diffuse reflectance, elemental analysis) of a novel boron peroxotungstate (BTBA)4H[BW4O24] (BTBA = benzyltributylammonium) is reported, along with its use in the homogeneous oxidation of cis-cyclooctene, geraniol, linalool and (-)-carveol with H 2O2 as oxidant and acetonitrile as solvent. High catalytic activity was registered for all the substrates studied under homogeneous conditions, namely 99% of conversion of geraniol after 2 h, 93% for linalool after 5 h, 74% for cis-cyclooctene after 6 h, and 100% for (-)-carveol after 2 h of reaction. Some oxidation studies were carried out with the Venturello complex, [PW4O24]3-, in the same conditions. Furthermore, the boron peroxotungstate (BW4) was immobilized using two different strategies: (a) BW4 anchored into a functionalized silica (aptesSiO2) giving BW4@aptesSiO2 and (b) BW4 encapsulated on a metal organic framework, commonly referred as MIL-101, giving BW4@MIL-101. The catalytic activity of both heterogeneous materials was investigated for geraniol oxidation and the results were compared with those obtained with BW4 under homogeneous conditions. The encapsulated boron peroxotungstate (BW4@MIL-101) gave rise to the best results, reaching complete conversion of geraniol after 3 h of reaction and 78% selectivity for 2,3-epoxygeraniol. Additionally, this heterogeneous catalyst could be reused without appreciable loss of catalytic activity, affording similar 2,3-epoxygeraniol selectivity. The heterogeneous catalysts' stability was also investigated after the oxidation reactions by different characterization techniques.
- Santos, Isabel C.M.S.,Balula, Salete S.,Sim?es, Mário M.Q.,Cunha-Silva, Luís,Neves, M. Gra?a P.M.S.,De Castro, Baltazar,Cavaleiro, Ana M.V.,Cavaleiro, José A.S.
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- Vanadyl arsenates as catalysts for selective oxidation of organic sulfides and alkenes
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Two vanadyl arsenates templated with ethylendiamonium (EnVAs) and piperazonium (PipVAs) were evaluated as catalysts for the oxidation of thioethers and alkenes, using H2O2 and t-butyl hydroperoxide (TBHP) as oxidants. The intrinsic activity of EnVAs was higher than that of PipVAs for the oxidation of sulfides. Similar results were obtained when using either H2O2 or TBHP as oxidants. However, the sterical effects were enhanced when TBHP was used and higher selectivities towards sulfoxides were achieved with this oxidant. The catalytic activity of the V-based materials in the epoxidation of simple alkenes and allylic alcohols was assessed. Upon reuse, both materials show no significant decrease in their catalytic properties.
- Berrocal, Teresa,Larrea, Edurne S.,Iglesias, Marta,Arriortua, Maria I.
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scheme or table
p. 176 - 182
(2011/03/23)
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- Two-step, stereoselective synthesis of linalyl oxides by asymmetric allylic O-alkylation
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Each of the four tetrahydrofuran linalyl oxides was prepared by a Sharpless asymmetric dihydroxylation of geranyl acetate with AD-mix-α or AD-mix-β, followed by a stereoselective palladium-mediated cyclization using the chiral ligand C3-TunePhos.
- Wan, Kanny K.,Litz, Jonathan P.,Vosburg, David A.
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experimental part
p. 2425 - 2428
(2011/02/16)
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- Gold catalysis in stereoselective natural product synthesis: (+)-linalool oxide, (-)-isocyclocapitelline, and (-)-isochrysotricine
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A stereoselective synthesis of the tetrahydrofuran-containing natural products (2S,5R)-(+)-linalool oxide (1), (-)-isocyclocapitelline (2), and (-)-isochrysotricine (3) is reported. Key steps are the copper-mediated SN2′-substitution of proparg
- Volz, Frank,Wadman, Sipke H.,Hoffmann-R?der, Anja,Krause, Norbert
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experimental part
p. 1902 - 1910
(2009/06/20)
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- Fungal biotransformation of (±)-linalool
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The biotransformation of (±)-linalool was investigated by screening 19 fungi. Product accumulation was enhanced by substrate feeding and, for the first time, lilac aldehydes and lilac alcohols were identified as fungal biotransformation byproduct using SPME-GC-MS headspace analysis. Aspergillus niger DSM 821, Botrytis cinerea 5901/02, and B. cinerea 02/FBII/2.1 produced different isomers of lilac aldehyde and lilac alcohol from linalool via 8-hydroxylinalool as postulated intermediate. Linalool oxides and 8-hydroxylinalool were the major products of fungal (±)-linalool biotransformations. Furanoid trans-(2R,5R)- and cis-(2S,5R)-linalool oxide as well as pyranoid trans-(2R,5S)- and cis-(2S, 5S)-linalool oxide were identified as the main stereoisomers with (3S,6S)-6,7-epoxylinalool and (3R,6S)-6,7-epoxylinalool as postulated key intermediates of fungal (±)-linalool oxyfunctionalization, respectively. With a conversion yield close to 100% and a productivity of 120 mg/L·day linalool oxides, Corynespora cassiicola DSM 62485 was identified as a novel highly stereoselective linalool transforming biocatalyst showing the highest productivity reported so far.
- Mirata, Marco-Antonio,Wuest, Matthias,Mosandl, Armin,Schrader, Jens
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p. 3287 - 3296
(2008/09/20)
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- Vanadium(V)-catalyzed oxidation of (3R)-linalool - The selective formation of furanoid linalool oxides and their conversion into isocyclocapitelline derivatives
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Oxidation of (3R)-linalool (2) with tert-butyl hydroperoxide (TBHP) occurs at the 6,7-position to selectively afford linalool oxide cis-1, if catalyzed by vanadium(V) Schiff base complexes 4. Substituted tetrahydrofuran cis-1 and its isomer trans-1 served
- Hartung, Jens,Drees, Simone,Geiss, Barbara,Schmidt, Philipp
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p. 223 - 226
(2007/10/03)
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- (Schiff-base)vanadium(v) complex-catalyzed oxidations of substituted bis(homoallylic) alcohols - Stereoselective synthesis of functionalized tetrahydrofurans
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Vanadium(v) complexes 4 have been prepared from tridentate Schiff-base ligands 3 and VO(OEt)3. All vanadium(v) compounds were characterized (IR, UV/Vis, and 51V NMR spectroscopy, and in selected examples by X-ray diffraction analysis) and were applied as oxidation catalysts for the stereoselective synthesis of functionalized tetrahydrofurans 2 starting from substituted bis(homoallylic) alcohols 1 (mono- or trisubstituted C-C double bonds). Oxidation of secondary or tertiary 1-alkyl-, 1-vinyl-, or 1-phenyl-substituted 5,5-dimethyl-4-penten-1-ols under optimized conditions [TBHP as primary oxidant and 1,2-(amino)indanol-derived vanadium(v) reagent 4g as catalyst] provided 2,5-cis-configured tetrahydrofurans in synthetically useful yields and diastereoselectivities (22-96% de). On the other hand, trans-disubstituted oxolanes (62%-96 de) were obtained from oxidations of 2- or 3-alkyl- and 2- or 3-phenyl-substituted 5,5-dimethyl-4-penten-1-ols bis(homoallylic) allyhc) alcohols. Treatment of 4-penten-1-ols (i.e. substrates with monosubstituted olefinic π-bonds) with TBHP and catalytic amounts of vanadium(v) complex 4g furnished trans-disubstituted tetrahydrofurans as major products (20-96% de), no matter whether an alkyl or a phenyl substituent was located in position 1, 2, or 3 of the alkenol chain. The mechanism of this reaction has been investigated in detail. Based on results from 51V NMR spectroscopy and competition kinetics, it proceeds by a transition metal-peroxy pathway. In an initial step, TBHP coordinates to, for example, N-(2-oxidophenyl)salicylideniminato-derived vanadium complex 4a. Subsequent alkenol binding gives rise to a "loaded" vanadium(v) peroxy complex (e.g. 60) which facilitates diastereoselective oxygen transfer, presumably onto a coordinated substrate. This step leads to the formation of functionalized tetrahydrofurans as major products. TBHP binding to the remaining vanadium(v) complex then allows a regeneration of the active oxidant, for example peroxy complex 57. The origin of the observed diastereoselectivity in this oxidation has been studied in an independent stereochemical analysis. Thus, diastereomerically enriched epoxy alcohol (1R,4R)-10 was prepared. Its treatment with 1,2-(amino)indanol-derived vanadium complex 4g affords a 91:9 mixture of cis-2-(1-hydroxy-1-methylethyl)-5-(phenyl)tetrahydrofuran (cis-6) and cis-2,2-dimethyl-6-(phenyl)tetrahydropyran-3-ol (cis-7). Similarly, a 39:61 mixture of heterocycles trans-6 and trans-7 was obtained from epoxy alcohol (1S,4R)-10, if treated with Lewis acid 4g. ( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003).
- Hartung, Jens,Drees, Simone,Greb, Marco,Schmidt, Philipp,Svoboda, Ingrid,Fuess, Hartmut,Murso, Alexander,Stalke, Dietmar
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p. 2388 - 2408
(2007/10/03)
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- Oxidation of α-hydroxy containing monoterpenes using titanium silicate catalysts: Comments on regioselectivity and the role of acidity
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The regioselective epoxidation of monoterpenes in the liquid phase has been studied using the titanosilicates TS-1 and TiAlβ. A range of oxidants (hydrogen peroxide, tert-butyl hydroperoxide and urea-hydrogen peroxide complex) have been studied in detail. The allylic alcohols linalool and geraniol have been studied alongside the non-allylic alcohol citronellol and the diene dihydromyrcene to help determine the role of the hydroxy group in these reactions. Dihydromyrcene is selectively epoxidised at the more electron rich double bond regardless of the catalyst-oxidant-solvent system used. Geraniol can undergo allylic assisted epoxidation with TS-1-acetone-hydrogen peroxide and TiAlβ-acetonitrile-urea-hydrogen peroxide. With TiAlβ-hydrogen peroxide-methanol, the reaction shows an induction period in the conversion of geraniol which is considered to be characteristic of the autocatalytic removal of titanium from the catalyst framework. Reactions with citronellol show this titanium removal is entirely due to the presence of the allylic alcohol moiety. Finally, epoxidation of linalool and the subsequent in situ conversion of the epoxide to the furano- and pyrano-oxides were studied. The ratio of furano- and pyrano-oxides formed was considered to be due, in part, to the pore geometry and the Br?nsted acidity of the catalyst.
- Schofield, Lee J.,Kerton, Owain J.,McMorn, Paul,Bethell, Donald,Ellwood, Simon,Hutchings, Graham J.
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p. 1475 - 1481
(2007/10/03)
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- From rational octahedron design to reticulation serendipity. A thermally stable rare earth polymeric disulfonate family with CdI2-like structure, bifunctional catalysis and optical properties
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A new family of lanthanide disulfonates Ln(OH)(NDS)- (H2O), (Ln = La, Pr and Nd; NDS = 1,5-naphthalenedisulfonate) was designed and hydrothermally synthesized; this is the first example of a disulfonate ligand coordinated to six different Ln atoms; these materials, with high thermal stability, act as active and selective bifunctional catalysts in oxidation and epoxide ring opening; strong luminescence from the optically active Nd center was observed.
- Snejko, Natalia,Cascales, Concepcion,Gomez-Lor, Berta,Gutierrez-Puebla, Enrique,Iglesias, Marta,Ruiz-Valero, Caridad,Monge, M. Angeles
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p. 1366 - 1367
(2007/10/03)
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- Rearrangements of epoxides of linalool and nerolidyl acetate in acid media
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The behavior of epoxides of linalool and cis-nerolidyl acetate was comparatively investigated in acids of various strength with the goal of establishing the effect of the structure of the initial compound and the medium character on the main direction of cationoid rearrangement. Linalool epoxides undergo cyclization of solid acid catalysts affording oxygen-containing heterocyclic compounds whereas the nerolidyl acetate epoxides yield the ketones originating from the opening of the epoxy ring followed by 1,2-hydride shift. 10,11-Epoxy derivative of cis-nerolidyl acetate affords 7-oxanorbornane as a minor product.
- Khomenko,Tatarova,Korchagina,Barkhash
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p. 498 - 506
(2007/10/03)
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- Oxidative cyclization based on reversing the polarity of enol ethers and ketene dithioacetals. Construction of a tetrahydrofuran ring and application to the synthesis of (+)-nemorensic acid
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The utility of oxidative cyclization reactions for the construction of tetrahydrofuran rings has been examined. In these experiments, alcohol nucleophiles were found to be effective traps for radical cation intermediates generated from both enol ether and ketene dithioacetal groups, The reactivity of the alcohol trapping group appeared to lie between that of an enol ether and an allylsilane trapping group. The stereochemical outcome of cyclization reactions originating from the oxidation of an enol ether was found to be controlled by stereoelectronic factors. The utility of these cyclization reactions was illustrated with the synthesis of a key tetrahydrofuran building block for the synthesis of linalool oxide and rotundisine. Cyclization reactions triggered by the oxidation of a ketene dithioacetal led to far greater levels of stereoselectivity. The stereochemical outcome of these reactions was shown to arise from steric factors involving the larger ketene acetal group. The synthetic utility of cyclizations utilizing ketene dithioacetal derived radical cations was demonstrated by completing an asymmetric synthesis of (+)-nemorensic acid. Finally, the reactions were shown to be compatible with the use of an amide nucleophile and the direct formation of a lactone product.
- Liu, Bin,Duan, Shengquan,Sutterer, Angela C.,Moeller, Kevin D.
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p. 10101 - 10111
(2007/10/03)
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- Diastereoselective titanocene-catalyzed oxidative cyclization of bishomoallylic alcohols
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Bishomoallylic alcohols are converted in good yields and diastereoselectivity into tetrahydrofuranols and tetrahydropyranols by Cp2TiCl2/t-butyl hydroperoxide/activated 4? molecular sieves system.
- Lattanzi,Della Sala,Russo,Scettri
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p. 1479 - 1481
(2007/10/03)
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- Organic processes initiated by non-classical energy sources
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Non-classical energy sources such as microwave energy, ultrasound and mechanoenergy and their combination with UV-VIS radiation are new tools in synthetic chemistry and chemical processing. Here we describe the application of microwave treatment for selected organic reactions such as (i) enzymatic transesterification of optically active alcohols, (ii) mercury-sensitized gas-phase photolysis of hydrocarbons in the microwave field, (iii) environmentally benign oxidations of olefins and (iv) the application of mechanoenergy separately and in combination with microwave irradiation for special oxidation reactions. Copyright
- Nuechter, Matthias,Ondruschka, Bernd,Jungnickel, Anja,Mueller, Ute
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p. 579 - 586
(2007/10/03)
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- Selective epoxidation of monoterpenes with methyltrioxorhenium and H2O2
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In the presence of pyridine as a co-catalyst, CH3ReO3 catalyses the epoxidation of terpenes such as α-pinene with H2O2 with minimal rearrangement of the epoxide. Pyridine is also critical to suppress isomerisation of the olefin substrate (in case of nerol, geraniol). The reaction can be directed towards selective single or double epoxidation, or in one step towards the rearranged product (e.g. from linalool to the ring- closure product linalool oxide.
- Villa De P., Aida L.,De Vos, Dirk E.,Montes De C., Consuelo,Jacobs, Pierre A.
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p. 8521 - 8524
(2007/10/03)
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- Simple synthesis of karahanaenone
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Karahanaenone 1 has been prepared from linalool 3. Linalool 3 is cyclized to the corresponding tetrahydrofuran-type cyclic ethers 4a-c on treatment with PhSeCl, N-bromosuccinimide, and 3-chloroperbenzoic acid, respectively. 4a-c on further treatment with various reagents, provide allylic cyclic ether 6 which is converted to 1 via 2.
- Konstantinovic, S.,Bugarcic, Z.,Marjanovic, Lj.,Gojkovic, S.,Mihailovic, M. Lj.
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p. 1169 - 1170
(2007/10/03)
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- Biotransformation of linalool to furanoid and pyranoid linalool oxides by Aspergillus niger
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Biotransformation of (±)-linalool with submerged shaking cultures of Aspergillus niger, particularly A. niger ATCC 9142, yielded a mixture of cis- and trans-furanoid linalool oxide (yield 15-24%) and cis- and trans-pyranoid linalool oxide (yield 5-9%). Biotransformation of (R)-(-)-linalool with the same strain yielded almost pure trans-furanoid and trans-pyranoid linalool oxide (ee > 95). These conversions were purely biocatalytic, since in acidified water (pH 3.5) almost 50% linalool was recovered unchanged, the rest was lost by evaporation. The biotransformation was also carried out with growing surface cultures.
- Demyttenaere, Jan C.R.,Willemen, Hendra M.
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p. 1029 - 1036
(2007/10/03)
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- Palladium(0)-catalysed synthesis of cis- and trans-linalyl oxides
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Linalyl oxides are obtained from (Z)- or (E)-6,7-dihydroxy-3,7-dimethyl-oct-2-enyl carbonate in the presence of Pd2(dba)3 in association with various ligands.
- Fournier-Nguefack, Christelle,Lhoste, Paul,Sinou, Denis
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p. 4353 - 4362
(2007/10/03)
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- Selective Oxidation of Monoterpenes with Hydrogen Peroxide Catalyzed by Peroxotungstophosphate (PCWP)
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Catalytic epoxidation of monoterpenes with aqueous hydrogen peroxide catalyzed by peroxotungstophosphate (PCWP) under biphase conditions using chloroform as the solvent was examined.A variety of terpenes was oxidized to the corresponding monoepoxides or diepoxides in good yields under mild conditions.For example, limonene (1) was converted into limonene oxide (1a) in which the cyclohexene double bond was selectively epoxidized in almost quantitative yield.The oxidation of γ-terpinene (2) with 2.2 equiv of 35percent H2O2 took place with high stereoselectivity to give cis-diepoxide 2c.In terpenes bearing electron-withdrawing groups such as neryl acetate (3), geranyl acetate (4), citral (5), and geranyl nitrile (6), the double bonds remote from the substituents were epoxidized in preference to the others.The epoxidation of linalool (9) by the present catalyst-oxidant system produced the cyclic products, hydroxy furan 9a and hydroxy pyran 9b, rather than epoxide. tert-Butyl alcohol was successfully employed as the solvent by treating a hydrogen peroxide solution of tert-butyl alcohol with MgSO4 prior to use.The regioselectivities in the epoxidation of monoterpenes can be favorably explained from the electron densities of the double bonds which were estimated using the CAChe system.
- Sakaguchi, Satoshi,Nishiyama, Yutaka,Ishii, Yasutaka
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p. 5307 - 5311
(2007/10/03)
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- Large Pore Bifunctional Titanium-Aluminosilicates: the Inorganic Non-enzymatic Version of the Epoxidase Conversion of Linalool to Cyclic Ethers
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Bifunctional aluminosilicate catalysts containing framework Ti are prepared, with two different topologies and pore sizes; these samples contain both acid and oxidizing catalytic sites and are highly selective for carrying out multistep reactions with selectivities close to those obtained with epoxidases, this is shown to occur for the oxidation of linalool to cyclic hydroxy ethers.
- Corma, A.,Iglesias, M.,Sanchez, F.
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p. 1635 - 1636
(2007/10/02)
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- Neutral Compounds from Male Castoreum of North Americal Beaver, Castor canadensis
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North American beavers (Castor canadensis) mark their territories with castoreum, the strong-smelling paste in their castor sacs. In their own territories, beavers respond with scent marking to experimental scent marks that consist of strange castoreum (or selected components). In part, the unique odor of castoreum is due to large amounts of phenolic compounds and neutral compounds. Purified neutral compounds were analyzed by GC, GC-MS, and NMR; identities of the neutral compounds were confirmed by comparing the properties of authentic compounds with those of the isolated compounds. We identified 13 neutral compounds that had not been reported before for castoreum. Most of these are oxygen-containing monoterpens. Of the nine neutral compounds reported by Lederer (1949), only three are confirmed in our analysis; the other six neutral compounds are either absent or are not volatile enough to be detected by our methods. Eight compounds - 6-methyl-1-heptanol, 4,6-dimethyl-1-heptanol, isopinocamphone, pinocamphone, two linalool oxides, and their acetates - were synthesized for structure identification and bioassays.
- Tang, Rong,Webster, Francis X.,Mueller-Schwarze, Dietland
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p. 1745 - 1762
(2007/10/03)
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- The Use of Acyclic Monoterpenes in the Preparation of β-pyrones; Synthesis of the Right-hand Fragment of Usneoidone E
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The right hand fragment, 36, of Usneoidone E, 1, a powerful antiviral and antitumoural agent has been synthesized from the β-pyrone 32.Using lanalool as starting material, a 2,2,6,6-tetrasubstituted dihydropyrane 20, precursor of 32 and 33, was prepared. 20 was also synthesized from geranyl acetate through selenide 7, and is a versatile precursor for the synthesis of tetraprenyltoluquinols.Unambiguous 13C NMR assignment has been done by 2D correlations.
- Urones, Julio G.,Diez, David,Marcos, Isidro S.,Basabe, Pilar,Lithgow, Anna M.,et al.
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p. 3691 - 3704
(2007/10/02)
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- Optical Isomers of Linalool and Linalool Oxides in Tea Aroma
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The main aroma components of oolong and black tea, linalool and four diastereomers of linalool oxides (LOs), were enantioselectively isolated by capillary gas chromatography, using a column coated with an optically active liquid phase, permethylated β-cyclodextrin.The R/S ratio varied among linalool and LOs, and among the different types of tea, the ratio for a particular compound also being different.However, the complete patterns of R/S ratio were similar in the semi-fermented and fermented teas, respectively.Using a specific cultivar of black tea, the R/S ratio for each of the five compounds was compared in the free state in black tea with that of an aglycone of the glycoside in fresh tea leaves or in black tea.While the e.e. values of the compounds varied, those for a specific compound were similar, except for linalool, regardless of their free or combined state.These results show that POs are not directly transformed from linalool, but are formed enzymatically from glycoside precursors.
- Wang, Dongmei,Ando, Kiyoshi,Morita, Kae,Kubota, Kikue,Kobayashi, Akio
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p. 2050 - 2053
(2007/10/02)
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- A VERY SIMPLE OXIDATION OF OLEFINS AND KETONES WITH UHP - MALEIC ANHYDRIDE
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The oxidation of olefins and ketones to oxiranes and esters, respectively, is carried out with the UHP(urea-hydrogen peroxide complex) - maleic anhydride system in a mild and very simple procedure.
- Astudillo, Luis,Galindo, Antonio,Gonzalez, Antonio G.,Mansilla, Horacio
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p. 1075 - 1080
(2007/10/02)
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- Synthesis of All Four Stereoisomers of Enantiomerically Pure cis- and trans-Linalyl Oxides
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The four enantiomerically pure cis- and trans-linalyl oxides can be prepared in one step and good yield from (6S)- or (6R)-6,7-dihydroxygeranyl phenylcarbamate.
- Meou, A.,Bouanah, N.,Archelas, A.,Zhang, X. M.,Guglielmetti, R.,Furstoss, R.
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p. 752 - 753
(2007/10/02)
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- Hydrocobaltation Reactions of 1,3-Dienes. Regioselective Hydroxylation of Myrcene to Geraniol and to (+/-)-Linalool via Allylcobaloxime Intermediates
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Hydrocobaltation of myrcene (3) by pyridinatocobaloxime leads to a 2:1 mixture of the E- and Z-allylcobaloxime (4a) and (4b) in good yield.When a solution of the cobaloximes (4a) and (4b) in toluene is heated in the presence of tetramethylpiperidine oxide (TEMPO) the hydroxylamines (7a) and (7b) result, which can be converted into geraniol (8a) and nerol (8b) by reduction using zinc in acetic acid.By contrast, in the presence of molecular oxygen, the allylcobaloxime (4) is converted into the allylperoxycobaloxime (15) which on reduction produces (+/-)-linalool (16).In addition, when the cobaloxime (15) is heated with TEMPO it undergoes cyclisation to the tetrahydrofuran (17), precursor to (+)-linalool oxide (18).Whereas the 1,3-dienes (20)-(24) all failed to undergo hydrocobaltation reactions, both cobaloximes (27) and (28) were easily obtained from 2-methyl- (25) and 2,3-dimethyl-buta-1,3-diene (26), respectively.Using similar chemistry to that described for compound (4), the allylcobaloxime (27) was smoothly converted into the hydroxylamine (29) and into the epoxy-TEMPO derivative (32).
- Howell, Amy R.,Pattenden, Gerald
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p. 2715 - 2720
(2007/10/02)
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- Regioselective Hydroxylations of 1,3-Dienes via Hydrocobaltation Reactions. Facile Conversion of Myrcene to Geraniol and to (+/-)-Linalool
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Regioselective (1,4-) hydrocobaltation of myrcene (1) leads to a 2:1 mixture of (E)- and (Z)-allylcobaloximes (2) which can be converted via the corresponding hydroxylamines (5) to geraniol (6a) and nerol (6b); by contrast, in the presence of molecular oxygen, (2) is converted into the peroxyallylcobalt complex (7), a precursor to linalool (8) and to linalool oxide (10).
- Howell, Amy R.,Pattenden, Gerald
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p. 103 - 104
(2007/10/02)
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- 6,7-EPOXY-LINALOOL AND RELATED OXYGENATED TERPENOIDS FROM CARICA PAPAYA FRUIT
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Oxyganated terpenoids derived from linalool, a major constituent of papaya fruit volatiles, were studied by HRGC and HRGC-MS.Using a sample preparation technique suitable for the separation and enrichment of polar compounds, the two diastereoisomers of 6,7-epoxy-linalool, 2,6-dimethyl-octa-1,7-diene-3,6-diol, 2,6-dimethyl-octa-3,7-diene-2,6-diol, (E)- and (Z)-2,6-dimethyl-octa-2,7-diene-1,6-diol and 2,6-dimethyl-oct-7-ene-2,3,6-triol were identified.Additionally, each of four diastereoisomeric epoxy-linalool oxides in their furanoid and pyranoid forms were detected for the first time as natural plant constituents.Biogenetic pathways for formation and metabolism of the oxygenated linalool derives are discussed. Key Word Index - Carica papaya; Caricaceae; papaya fruit; 6,7-epoxy-linalool; epoxy-linalool oxides; terpene polyols.
- Winterhalter, Peter,Katzenberger, Doris,Schreier, Peter
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p. 1347 - 1350
(2007/10/02)
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- Synthesis of Karahanaenone
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Karahanaenone (1) has been prepared from dehydrolinalyl acetate.Electrochemical epoxidation of dehydrolinalyl acetate provided the corresponding epoxide 6a (75percent) which was converted to keto acetate 7a (82percent) by an electrogenerated acid-catalyzed rearrangement.Hydrogenation followed by alkaline hydrolysis gave 6-hydroxy-2,6-dimethyl-7-octen-3-one (7c) (86percent), which was subjected to thermal dehydration at 200 deg C to give 1 (85percent) via Claisen type rearrangement of the intermediate 2-methyl-2-ethenyl-5-propylidenetetrahydrofuran (2).An alternative route to 1 via thermolysis of the xanthate of 1-(5-ethenyl-5-methyl-2-tetrahydrofuranyl)-1-methylethanol (10b) is also described.
- Uneyama, Kenji,Date, Takasi,Torii, Sigeru
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p. 3160 - 3163
(2007/10/02)
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- Oxidative Cyclization of Linalol by Various Microorganisms
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(+/-) Linalol is cyclized into cis and trans linalol oxides by various microorganisms.This reaction, assuming an intermediate epoxidation step, is analogous to the corresponding step proposed for the biosynthesis of ionophorous antibiotics.
- David, Lucien,Veschambre, Henri
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p. 1487 - 1490
(2007/10/02)
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- PREPRATION D'OXYDES DE LINALOL PAR BIOCONVERSION
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Microbial cyclisation of linalol (+), (-) and (+-) by a nigericin-producing Streptomyces albus gives linalol oxydes.Cis linalol oxyde gives opposite signs for the rotatory power when measured neat or in solution.
- David, L.,Veschambre, H.
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p. 543 - 546
(2007/10/02)
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- OBTENTION DE TETRAHYDROFURANNES FONCTIONNALISES LORS DE L'ACTION DE REACTIFS ORGANOMETALLIQUES SUR DES γ,δ-EPOXYCETONES
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The reaction of organolithium and organomagnesium reagents with γ,δ-epoxy ketones affords functionalized tetrahydrofurans by intramolecular cyclisation of an intermediate addition alkoxide.This cyclization is regioselective: the formation of a tetrahydrofuran is always observed while the tetrahydropyran isomer is never obtained.The oxiran ring opening is stereospecific and occurs with inversion of configuration.However, addition of the organometallic reagent to the carbonyl function is of low stereoselctivity and cyclization affords the two cis and trans isomers of the tetrahydrofuran ring in an approximately 1/1 ratio.
- Chastrette, Maurice,Axiotis, Georges P.
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p. 139 - 147
(2007/10/02)
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