- 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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- 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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- 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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- 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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- 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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- 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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- 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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