- One-pot synthesis at room temperature of epoxides and linalool derivative pyrans in monolacunary Na7PW11O39-catalyzed oxidation reactions by hydrogen peroxide
-
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
-
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
-
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
-
p. 813 - 825
(2019/01/04)
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- Asymmetric synthesis and structure-activity studies of the fungal metabolites colletorin A, colletochlorin A and their halogenates analogues
-
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
-
p. 3912 - 3923
(2018/06/08)
-
- Method for preparing furan-type oxidized linalool
-
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.
- -
-
Paragraph 0030-0057
(2017/09/13)
-
- 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
-
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.
-
p. 593 - 599
(2016/12/16)
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- UTL titanosilicate: An extra-large pore epoxidation catalyst with tunable textural properties
-
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
-
-
- Unusually Broad Substrate Profile of Self-Sufficient Cytochrome P450 Monooxygenase CYP116B4 from Labrenzia aggregata
-
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
-
p. 2443 - 2449
(2015/03/03)
-
- Unusually Broad Substrate Profile of Self-Sufficient Cytochrome P450 Monooxygenase CYP116B4 from Labrenzia aggregata
-
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
-
p. 2443 - 2449
(2015/08/24)
-
- Catalytic performance of a boron peroxotungstate complex under homogeneous and heterogeneous conditions
-
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.
-
-
- Vanadyl arsenates as catalysts for selective oxidation of organic sulfides and alkenes
-
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.
-
scheme or table
p. 176 - 182
(2011/03/23)
-
- Fungal biotransformation of (±)-linalool
-
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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- Oxidation of α-hydroxy containing monoterpenes using titanium silicate catalysts: Comments on regioselectivity and the role of acidity
-
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)
-
- From rational octahedron design to reticulation serendipity. A thermally stable rare earth polymeric disulfonate family with CdI2-like structure, bifunctional catalysis and optical properties
-
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
-
p. 1366 - 1367
(2007/10/03)
-
- Diastereoselective titanocene-catalyzed oxidative cyclization of bishomoallylic alcohols
-
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
-
p. 1479 - 1481
(2007/10/03)
-
- 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
-
p. 579 - 586
(2007/10/03)
-
- Biotransformation of linalool to furanoid and pyranoid linalool oxides by Aspergillus niger
-
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.
-
p. 1029 - 1036
(2007/10/03)
-
- Selective epoxidation of monoterpenes with methyltrioxorhenium and H2O2
-
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)
-
- Simple synthesis of karahanaenone
-
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.
-
p. 1169 - 1170
(2007/10/03)
-
- Palladium(0)-catalysed synthesis of cis- and trans-linalyl oxides
-
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
-
p. 4353 - 4362
(2007/10/03)
-
- Selective Oxidation of Monoterpenes with Hydrogen Peroxide Catalyzed by Peroxotungstophosphate (PCWP)
-
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
-
p. 5307 - 5311
(2007/10/03)
-
- Neutral Compounds from Male Castoreum of North Americal Beaver, Castor canadensis
-
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
-
p. 1745 - 1762
(2007/10/03)
-
- Large Pore Bifunctional Titanium-Aluminosilicates: the Inorganic Non-enzymatic Version of the Epoxidase Conversion of Linalool to Cyclic Ethers
-
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.
-
p. 1635 - 1636
(2007/10/02)
-
- 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
-
p. 1075 - 1080
(2007/10/02)
-
- Hydrocobaltation Reactions of 1,3-Dienes. Regioselective Hydroxylation of Myrcene to Geraniol and to (+/-)-Linalool via Allylcobaloxime Intermediates
-
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
-
p. 2715 - 2720
(2007/10/02)
-
- Regioselective Hydroxylations of 1,3-Dienes via Hydrocobaltation Reactions. Facile Conversion of Myrcene to Geraniol and to (+/-)-Linalool
-
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
-
p. 103 - 104
(2007/10/02)
-
- Synthesis of Karahanaenone
-
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
-
p. 3160 - 3163
(2007/10/02)
-
- Oxidative Cyclization of Linalol by Various Microorganisms
-
(+/-) 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)
-
- OBTENTION DE TETRAHYDROFURANNES FONCTIONNALISES LORS DE L'ACTION DE REACTIFS ORGANOMETALLIQUES SUR DES γ,δ-EPOXYCETONES
-
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)
-