- Stereochemical investigations on the biosynthesis of achiral (Z)-γ-bisabolene in Cryptosporangium arvum
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A newly identified bacterial (Z)-γ-bisabolene synthase was used for investigating the cyclisation mechanism of the sesquiterpene. Since the stereoinformation of both chiral putative intermediates, nerolidyl diphosphate (NPP) and the bisabolyl cation, is lost during formation of the achiral product, the intriguing question of their absolute configurations was addressed by incubating both enantiomers of NPP with the recombinant enzyme, which resolved in an exclusive cyclisation of (R)-NPP, while (S)-NPP that is non-natural to the (Z)-γ-bisabolene synthase was specifically converted into (E)-β-farnesene. A hypothetical enzyme mechanistic model that explains these observations is presented.
- Rinkel, Jan,Dickschat, Jeroen S.
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supporting information
p. 789 - 794
(2019/04/17)
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- Isotope sensitive branching and kinetic isotope effects to analyse multiproduct terpenoid synthases from Zea mays
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Multiproduct terpene synthases TPS4-B73 and TPS5-Delprim from Zea mays exhibit isotopically sensitive branching in the formation of mono- and sesquiterpene volatiles. The impact of the kinetic isotope effects and the stabilization of the reactive intermediates by hyperconjugation along with the shift of products from alkenes to alcohols are discussed.
- Gatto, Nathalie,Vattekkatte, Abith,K?llner, Tobias,Degenhardt, J?rg,Gershenzon, Jonathan,Boland, Wilhelm
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supporting information
p. 3797 - 3800
(2015/03/30)
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- Heteropoly acid catalyzed cyclization of nerolidol and farnesol: Synthesis of α-bisabolol
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Heteropoly acid H3PW12O40 is an active and environmentally friendly homogeneous catalyst for the synthesis of α-bisabolol, a high-priced and highly demanded ingredient for the fragrance, cosmetic and pharmaceutical industries, starting from more abundant biomass-based sesquiterpenic alcohols. The solvent nature remarkably affects the reaction pathways and product selectivity. In acetone solutions, α-bisabolol can be obtained in 55-60% GC yields from nerolidol and 60-70% GC yields from farnesol at complete substrate conversions, which are probably the best results ever reported for these reactions. α-Bisabolol synthesized by this method contains no farnesol, which is a potentially allergenic compound and should be avoided in the commercially used α-bisabolol. This advantage is especially important because the distillative separation of α-bisabolol and farnesol is a troublesome task. The catalyst shows high turnover numbers and operates under mild nearly ambient conditions.
- De Meireles, Augusto L.P.,Costa, Maíra Dos Santos,Da Silva Rocha, Kelly A.,Gusevskaya, Elena V.
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p. 271 - 275
(2015/07/07)
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- Biomimetic total synthesis of (-)-neroplofurol and (+)-ekeberin D4triggered by hydrolysis of terminal epoxides
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To accumulate the chemi cal basis of epoxide-opening cascade biogenesis, chemical syntheses of sesqui- and triterpenoids were performed. The biomi metic total syntheses of (-)-neroplofurol (1) and (+)-ekeberin D4(2) were accomplished by protic acid-catalyzed hydrolysis of the terminal epoxide from nerolidol diepoxide 3 and squalene tetraepoxide 4 through single and double 5-exo cyclizations in intermediates 5 and 6, respectively. This chemical reaction mimics the direct hydrolysis mechanism of epoxide hydrol ases, enzymes that catalyze an epoxide-opening reaction to finally produce vicinal diols.
- Kodama, Takeshi,Aoki, Shingo,Matsuo, Tomoki,Tachi, Yoshimitsu,Nishikawa, Keisuke,Morimoto, Yoshiki
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p. 1662 - 1664
(2015/02/19)
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- Method for Converting Farnesol to Nerolidol in the Presence of Alpha-Bisabolol
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A method for converting farnesol to nerolidol in the presence of alpha-bisabolol including providing or preparing a mixture of alpha-bisabolol, farnesol, and one or more catalysts for selective isomerization of farnesol to nerolidol in the presence of alpha-bisabolol, and converting at least a portion of the farnesol to nerolidol.
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Paragraph 0138 - 0139
(2013/11/06)
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- Biosynthesis of the sesquiterpene botrydial in Botrytis cinerea. Mechanism and stereochemistry of the enzymatic formation of presilphiperfolan-8β-ol
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(Figure Presented) Presilphiperfolan-8β-ol synthase, encoded by theBcBOT2 gene from the necrotrophic plant pathogen Botrytis cinerea, cata lyzes the multistep cyclization of farnesyl diphosphate (2) to the tricyclic sesquiterpene alcohol presilphiperfolan-8β-ol (3), the preursor of the phytotoxin botrydial, a strain-dependent fungal virulence factor. Incubation of (1R)-[1-2H]farnesyl diphosphate (2b) with recombinant presilphiperfolan-8β-ol synthase gave exclusively (5R)-[5α-2H]-3b, while complementary incubation of (1S)-[1-2H]FPP (2c) gave (5S)-[5β-2H]-3c. These results establishedthat cyclization of farnesyl diphosphate involves displacement of the d iphosphate group from C-1 with net inversion of configuration and ruled out the proposed intermediacy of the cisoid conformer of nerolidyl diphosphate (9) in the cyclization. While not a mandatory intermediate, (3R)-nerolidyl diphosphate was shown to act as a substrate surrogate. Cyclization of [13,13,13-2H3] farnesyl diphosphate (2d) gave [14,14,14-2H3]-3d, thereby establishing that electrophilic attack takes place exclusively on the si face of the 12,13-double bond of 2. The combined results provide a detailed picture of theconformation of enzyme-bound farnesyl diphosphate at the active site of presilphiperfolan-8β-ol synthase.
- Wang, Chieh-Mei,Hopson, Russell,Lin, Xin,Cane, David E.
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supporting information; experimental part
p. 8360 - 8361
(2009/10/24)
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- Method for Producing Alpha-Bisabolol from Farnesol
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The present invention relates to a process for preparing α-bisabolol, comprising the reaction of farnesol in the presence of a ketone, of a sulfonic acid and of a further strong acid.
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Page/Page column 3
(2008/12/04)
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- NEW REACTION WITH PRIMARY ALLYLIC ALCOHOLS
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The invention relates to a process of reacting a primary allylic alcohol with a compound containing a) a metal selected from the group consisting of Ag, Au, Ce, Mn, Ni, Ru, Re, Zn and Co preferably Ag and b) an oxidant like TEMPO (2,2',6,6'-tetra-methylpiperidin- 1-oxyl) or its derivates and c) a co-oxidants selected from the group of peroxodisulfates (PDS), H2SO5, H2O2, NaOCl, O2, KOCl, and air.
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Page/Page column 9
(2008/12/08)
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- Hydrogenation on granular palladium-containing catalysts: I. Hydrogenation of tertiary acetylene alcohols
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Commercial granular palladium catalyst (0.5% of Pd on γ-Al 2O3) was modified by treating with zinc acetate (type 1) or successively with zinc acetate and ammonia (type 2). The treatment significantly increased the hydrogenation selectivity for a triple bond into a double bond: to 85.3-93.1% with the type 1 catalyst and to 96.3-97.8% with the type 2 catalyst. A construction of an autoclave with a fixed bed of the granular catalyst is described.
- Tolkacheva,Kislyi,Taits,Semenov
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p. 150 - 152
(2007/10/03)
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- The synthesis of (3R)-nerolidol
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The sesquiterpene natural product (3R)-nerolidol has been prepared in six steps starting from (3R)linalool.
- Cane, David E.,Ha, Hyun-Joon,McIlwaine, Douglas B.,Pascoe, Keith O.
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p. 7553 - 7554
(2007/10/02)
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- SEMIHYDROGENATION OF ACETYLENES; MODIFIED LINDLAR CATALYST
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The effect of doping Lindlar catalyst with different metal salts (shown in Table 1) on selectivity, during semihydrogenation of some acetylenes to the corresponding olefins, has been studied.Lindlar catalyst modified with MnCl2 has been found to be more selective and reproducible.
- Rajaram, J.,Narula, A. P. S.,Chawla, H. P. S.,Dev, Sukh
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p. 2315 - 2322
(2007/10/02)
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- (10R, 11R)-(+)-SQUALENE-10, 11-EPOXIDE: ISOLATION FROM LAURENCIA OKAMURAI AND THE ASYMMETRIC SYNTHESIS
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From a red alga Laurencia okamurai, (10R, 11R)-(+)-squalene-10, 11-epoxide 1 was isolated and its asymmetric synthesis has been achieved starting from trans, trans-farnesol.
- Kigoshi, Hideo,Ojika, Makoto,Shizuri, Yoshikazu,Niwa, Haruki,Yamada, Kiyoyuki
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p. 5413 - 5414
(2007/10/02)
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