- Chemoenzymatic Synthesis of the Intermediates in the Peppermint Monoterpenoid Biosynthetic Pathway
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A chemoenzymatic approach providing access to all four intermediates in the peppermint biosynthetic pathway between limonene and menthone/isomenthone, including noncommercially available intermediates (-)-trans-isopiperitenol (2), (-)-isopiperitenone (3), and (+)-cis-isopulegone (4), is described. Oxidation of (+)-isopulegol (13) followed by enolate selenation and oxidative elimination steps provides (-)-isopiperitenone (3). A chemical reduction and separation route from (3) provides both native (-)-trans-isopiperitenol (2) and isomer (-)-cis-isopiperitenol (18), while enzymatic conjugate reduction of (-)-isopiperitenone (3) with IPR [(-)-isopiperitenone reductase)] provides (+)-cis-isopulegone (4). This undergoes facile base-mediated chemical epimerization to (+)-pulegone (5), which is subsequently shown to be a substrate for NtDBR (Nicotiana tabacum double-bond reductase) to afford (-)-menthone (7) and (+)-isomenthone (8).
- Cheallaigh, Aisling Ní,Mansell, David J.,Toogood, Helen S.,Tait, Shirley,Lygidakis, Antonios,Scrutton, Nigel S.,Gardiner, John M.
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p. 1546 - 1552
(2018/08/04)
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- Engineering the "missing Link" in Biosynthetic (-)-Menthol Production: Bacterial Isopulegone Isomerase
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The realization of a synthetic biology approach to microbial (1R,2S,5R)-(-)-menthol (1) production relies on the identification of a gene encoding an isopulegone isomerase (IPGI), the only enzyme in the Mentha piperita biosynthetic pathway as yet unidentified. We demonstrate that Δ5-3-ketosteroid isomerase (KSI) from Pseudomonas putida can act as an IPGI, producing (R)-(+)-pulegone ((R)-2) from (+)-cis-isopulegone (3). Using a robotics-driven semirational design strategy, we identified a key KSI variant encoding four active site mutations, which confer a 4.3-fold increase in activity over the wild-type enzyme. This was assisted by the generation of crystal structures of four KSI variants, combined with molecular modeling of 3 binding to identify key active site residue targets. The KSI variant was demonstrated to function efficiently within cascade biocatalytic reactions with downstream Mentha enzymes pulegone reductase and (-)-menthone:(-)-menthol reductase to generate 1 from 3. This study introduces the use of a recombinant IPGI, engineered to function efficiently within a biosynthetic pathway for the production of 1 in microorganisms.
- Currin, Andrew,Dunstan, Mark S.,Johannissen, Linus O.,Hollywood, Katherine A.,Vinaixa, Maria,Jervis, Adrian J.,Swainston, Neil,Rattray, Nicholas J. W.,Gardiner, John M.,Kell, Douglas B.,Takano, Eriko,Toogood, Helen S.,Scrutton, Nigel S.
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p. 2012 - 2020
(2018/03/13)
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- Pinpointing a Mechanistic Switch Between Ketoreduction and “Ene” Reduction in Short-Chain Dehydrogenases/Reductases
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Three enzymes of the Mentha essential oil biosynthetic pathway are highly homologous, namely the ketoreductases (?)-menthone:(?)-menthol reductase and (?)-menthone:(+)-neomenthol reductase, and the “ene” reductase isopiperitenone reductase. We identified a rare catalytic residue substitution in the last two, and performed comparative crystal structure analyses and residue-swapping mutagenesis to investigate whether this determines the reaction outcome. The result was a complete loss of native activity and a switch between ene reduction and ketoreduction. This suggests the importance of a catalytic glutamate vs. tyrosine residue in determining the outcome of the reduction of α,β-unsaturated alkenes, due to the substrate occupying different binding conformations, and possibly also to the relative acidities of the two residues. This simple switch in mechanism by a single amino acid substitution could potentially generate a large number of de novo ene reductases.
- Lygidakis, Antonios,Karuppiah, Vijaykumar,Hoeven, Robin,Ní Cheallaigh, Aisling,Leys, David,Gardiner, John M.,Toogood, Helen S.,Scrutton, Nigel S.
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supporting information
p. 9596 - 9600
(2016/08/10)
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- Regioselective silver-mediated Kondakov-Darzens olefin acylation
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Enone construction: A silver-mediated olefin acylation reaction is described, in which five-, six-, and -seven-membered rings, tetrasubstituted olefins, bridged bicycles, spirocycles, and benzoxepinones are prepared. Highly selective intermolecular reactions are coupled to a Nazarov cyclization for the effective preparation of cyclopentenones, including the core of modhephene (see scheme). Copyright
- Barczak, Nicholas T.,Jarvo, Elizabeth R.
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supporting information; experimental part
p. 12912 - 12916
(2011/12/04)
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- Asymmetric hydrogenation of heteroaromatic ketones and cyclic and acyclic enones mediated by Cu(I)-chiral diphosphine catalysts
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Copper(I)-catalyzed asymmetric hydrogenation of heteroaromatic ketones, cyclic and acyclic enones is reported. The choice of the chiral diphosphine ligand highly influenced enantiose-lectivity as well as chemoselectivity. Highly enantioselective hydrogenation of ortho-substituted heteroaromatic ketones was achieved using BDPP as the ligand. In the 1,2-selective hydrogenation of acylic enone, SEGPHOS gave higher enantioselectivity than BDPP. On the other hand, the bulky ligand DTBM-SEGPHOS had a 1,4-selective nature, leading to the first highly 1,4-selective and enantioselective hydrogenation of cyclic enones.
- Shimizu, Hideo,Nagano, Takuto,Sayo, Noboru,Saito, Takao,Ohshima, Takashi,Mashima, Kazushi
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scheme or table
p. 3143 - 3146
(2010/03/24)
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- Highly enantio- and s-trans C=C bond selective catalytic hydrogenation of cyclic enones: Alternative synthesis of (-)-menthol
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A highly enantioselective catalytic hydrogenation of cyclic enones was achieved by using the combination of a cationic Rh1 complex, (S)-5,5′-bis{di(3,5-di-tert-butyl-4-methoxyphenylphosphino)}-4, 4′-bi-1,3-benzodioxole (DTBM-SEGPHOS), and (CH2CH 2PPh3Br)2. The presence of an s-cis C=C bond isopropylidene moiety on the cyclic enone influenced the enantioselectivity of the hydrogenation. Thus, the hydrogenation of 3-alkyl-6-isopropylidene-2- cyclohexen-1-one, which contains both s-cis and s-trans enones, proceeded in excellent enantioselectivity (up to 98% ee). To obtain high enantio- and s-trans selectivities, the addition of a halogen source to the cationic Rh complex was the essential step. With the key step of the s-trans selective asymmetric hydrogenation of piperitenone, we demonstrated a new synthetic method for optically pure (-)-menthol via three atom-economical hydrogenations. Moreover, we found that the complete s-trans and s-cis C=C bond selective reactions were also realized by the proper choice of both the chiral ligands and halides.
- Ohshima, Takashi,Tadaoka, Hiroshi,Hori, Kiyoto,Sayo, Noboru,Mashima, Kazushi
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scheme or table
p. 2060 - 2066
(2009/04/07)
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- Flavor and fragrance compositions
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The present invention provides a flavor and fragrance composition which comprises, as the active ingredient, an optically active (1S)-8-mercaptomenthone having an S-form/R-form mixing ratio for the configuration at the 4-position in the range of from 65:35 to 95:5 by weight, wherein the flavor and fragrance composition is for use in food and beverage, fragrances and cosmetics, pharmaceuticals or oral compositions and the like; a product which is scented with the flavor and fragrance composition; and a method for enhancing or modulating odor of the flavor and fragrance composition by adding the optically active (1S)-8-mercaptomenthone.
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Page/Page column 6
(2008/06/13)
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- Regio- and diastereoselective tandem addition-carbocyclization promoted by sulfanyl radicals on chiral perhydro-1,3-benzoxazines
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Radical addition-carbocyclization of 2-allyl-3-acyloyl-substituted perhydro-1,3-benzoxazines readily provides 3,4-disubstituted pyrrolidinone derivatives with total regioselectivity and good diastereoselectivity. The key step of the reaction is a tandem addition-5-exo-cyclization promoted by a sulfanyl radical.
- Pedrosa, Rafael,Andres, Celia,Duque-Soladana, Juan P.,Maestro, Alicia,Nieto, Javier
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p. 2985 - 2990
(2007/10/03)
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- Lipase-catalyzed resolution of p-menthan-3-ols monoterpenes: Preparation of the enantiomer-enriched forms of menthol, isopulegol, trans- and cis-piperitol, and cis-isopiperitenol
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A study on the enzymic resolution of the most common p-menthan-3-ol monoterpene isomers is described. Enantioenriched alcohols 1, 5, 10, 11 and 12 are obtained by means of the lipase-mediated kinetic acetylation of the corresponding racemic materials. The stereochemical aspects of the enzymic process have been investigated. We found that the structural features of the starting p-menthan-3-ol as well as the kind of lipase used, impacted strongly on the enantioselectivity of the resolution. The potentialities of this approach for preparative purposes are discussed.
- Serra, Stefano,Brenna, Elisabetta,Fuganti, Claudio,Maggioni, Francesco
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p. 3313 - 3319
(2007/10/03)
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- Mo(CO)6-promoted facile deoxygenation of α,β-epoxy ketones and α,β-epoxy esters
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Deoxygenation of α,β-epoxy ketones and α,β-epoxy esters is accomplished in high yields under mild and neutral conditions by the use of Mo(CO)6.
- Patra, Asit,Bandyopadhyay, Mausumi,Mal, Dipakranjan
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p. 2355 - 2357
(2007/10/03)
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- Catalytic osmium-assisted oxidative cleavage of olefins
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An osmium-assisted process for the oxidative cleavage of oxidizable organic compounds such as unsaturated organic compounds, including alkenes and olefins into aldehydes, carboxylic acids, esters, or ketones. The process uses a metal catalyst comprising osmium and a peroxy compound selected from the group consisting of peroxymonosulfuric acid and salts thereof to oxidatively cleave the oxidizable organic compound. In particular, the process enables aldehydes, carboxylic acids, esters, or ketones to be selectively produced from the corresponding mono-, 1,1-di-, 1,2-di-, tri-, or tetra-substituted olefins in a reaction that produces the result of ozonolysis but with fewer problems. The present invention further provides a process for oxidizing an aldehyde alone or with the osmium in an interactive solvent to produce an ester or carboxylic acid.
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- Method for producing 1-menthol
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Provided is a method for the production of 1-menthol, which comprises hydrogenation of piperitenone with a transition metal complex of a specified optically active phosphine to produce pulegone, hydrogenation of the obtained pulegone with a ruthenium-phosphine-amine complex in the presence of base to obtain pulegol, and further hydrogenation of the pulegol with a transition metal catalyst.
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- Method for producing 1-menthol
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Provided is a method for the production of 1-menthol, which comprises hydrogenation of piperitenone with a transition metal complex of a specified optically active phosphine to produce pulegone, hydrogenation of the obtained pulegone with a ruthenium-phosphine-amine complex in the presence of base to obtain pulegol, and further hydrogenation of the pulegol with a transition metal catalyst.
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- An efficient procedure for the preparation of (E)-α-alkylidenecycloalkanones mediated by a CeCl3·7H2O-NaI system. Novel methodology for the synthesis of (S)-(-)-pulegone
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2-Alkylidenecycloalkanones are powerful synthons used as the key intermediates in many important syntheses. Because of their potential, a general method of preparation from readily available starting materials, under very mild conditions, was considered to be worthwhile. Cerium(III) chloride heptahydrate in combination with sodium iodide in refluxing acetonitrile promotes a regio- and stereoselective β-elimination reaction to (E)-2-alkylidenecycloalkanones in 2-(1-hydroxyalkyl)cycloalkanones. The synthetic value of the present procedure is demonstrated by the synthesis of monoterpene (S)-(-)-pulegone (8) in its optically active form.
- Bartoli, Giuseppe,Bosco, Marcella,Dalpozzo, Renato,Giuliani, Arianna,Marcantoni, Enrico,Mecozzi, Tiziana,Sambri, Letizia,Torregiani, Elisabetta
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p. 9111 - 9114
(2007/10/03)
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- A novel case of diastereoselection in 5-exo radical cyclization promoted by hydrogen bonding
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Moderate stereocontrol in 5-exo radical cyclizations of N,N-disubstituted (-)-8-amino menthol derivatives, promoted by tributyltin hydride and AIBN, was achieved. The stereoselection was explained in terms of hydrogen bond formation in the 1,3-amino alcohol derivative. The presence of one additional stereocenter at the allylic chain enhanced the stereoselection giving a single cyclization stereoisomer. The cyclization products were easily converted into enantiopure 3-alkyl- or 2,3-dialkyl-substituted pyrrolidines.
- Pedrosa, Rafael,Andres, Celia,Duque-Soladana, Juan P.,Mendiguchia, Pilar
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p. 3727 - 3730
(2007/10/03)
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- A versatile cobalt(II)-Schiff base catalyzed oxidation of organic substrates with dioxygen: Scope and mechanism
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Cobalt(II) complex 1a-f derived from Schiff bases act as efficient catalysts during the oxidation of wide range of organic substrates(e.g. alkenes, alcohols, benzylic compounds and aliphatic hydrocarbons) with dioxygen in the presence of aliphatic aldehydes or ketones or ketoesters. EPR studies on 1a-f complexes suggest that the aliphatic carbonyl compounds promote the formation of a cobalt(II)-superoxo species responsible for the oxidation of organic compounds. These studies also demonstrate the role of ligands on cobalt in controlling the chemoselectivity of these oxidations. A plausible mechanistic rational is also provided for these oxidations.
- Punniyamurthy,Bhatia, Beena,Reddy, M. Madhava,Maikap, Golak C.,Iqbal, Javed
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p. 7649 - 7670
(2007/10/03)
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- Regio- and enantio-selective enolisations of cyclic ketones using chiral lithium amide bases
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Enolisations of 3-methylcyclohexanone 16, and of a trans-fused perhydroisoquinolone derivative 8, using several chiral lithium amide bases have been examined.In reactions involving a single enantiomer of the ketone 8, the use of a chiral base can result in enhancement or reversal of the normal regioselectivity of enolisation to give the enol silane derivatives 9 and 10, depending on the configuration of the base used.Similar matched and mismatched results are observed when (R)-3-methylcyclohexanone, (R)-16, is treated with either enantiomer of the chiral base 3.A new type of kinetic resolution, termed regiodivergent resolution, is observed when enolisation of the racemic ketones 8 or 16 is carried out using the chiral base 3.
- Bambridge, Kimberley,Clark, Barry P.,Simpkins, Nigel S.
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p. 2535 - 2542
(2007/10/02)
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- Cobalt catalyzed oxidation of secondary alcohols with dioxygen in the presence of 2-methylpropanal
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Cobalt schiff base complex 2 catalyses the oxidation of a wide range of secondary alcohols to the corresponding ketones in the presence of dioxygen and 2-methylpropanal.
- Kalra, Swinder Jeet Singh,Punniyamurthy,Iqbal, Javed
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p. 4847 - 4850
(2007/10/02)
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- Cobalt(II) Schiffs base complex catalysed oxidation of alcohols with dioxygen in the presence of ethyl 2-oxocyclopentanecarboxylate
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Cobalt(II) Schiffs base complex 1 catalyses the oxidation of primary and secondary alcohols to aldehydes and ketones respectively, in the presence of dioxygen and ethyl 2-oxocyclopentanecarboxylate 2 at 60-70° C.
- Punniyamurthy,Iqbal, Javed
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p. 4007 - 4010
(2007/10/02)
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- Ruthenium-Catalyzed Hydration of Nitriles and Transformation of δ-Ketonitriles to Ene-lactams: Total Synthesis of (-)-Pumiliotoxin C
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Hydration of nitriles with 1-2 equivalents of water can be performed efficiently by using RuH2(PPh3)4 catalyst to give the corresponding amides.Under the similar reaction conditions, δ-ketonitriles can be converted into the corresponding ene-lactams, which are versatile synthetic intermediates.The efficiency of the reaction is demonstrated by the short-step synthesis of (-)-pumiliotoxin C.
- Murahashi, Shun-Ichi,Sasao, Shigehiro,Saito, Eiichiro,Naota, Takeshi
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p. 8805 - 8826
(2007/10/02)
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- Potassium Chlorochromate on a Solid Support: A Convenient and Mild Reagent for the Oxidation of Alcohols
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The oxidation of primary and secondary alcohols by potassium chlorochromate supported on alumina or silica gel is reported.The results indicate that the yields in some cases depend on the support medium.Benzylic and secondary alcohols are oxidized in the best yields.The effect of solvent on the reaction is discussed and the conclusion is drawn that the best yields are obtained in non-polar solvents.
- Carlsen, Per H. J.,Husbyn, Mette,Braenden, Jon E,,Eliason, Robert
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p. 485 - 488
(2007/10/02)
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- Method of catalytically hydrolyzing alpha, beta-unsaturated carbonyl compounds
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Alpha, beta-unsaturated carbonyl compounds are hydrolyzed under alkaline conditions in the presence of water to produce additional carbonyl-containing compounds. High yields are obtained when the alkaline catalyst contains hydroxide ion and the pH is maintained in the range of about 11 to about 13.
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- Oxidation of Alcohols with Potassium Chlorochromate
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Potassium chlorochromate, KCrClO3, (KCC) is a versatile and inexpensive oxidation reagent.It converts secondary saturated, as well as allylic and benzylic alcohols to the corresponding carbonyl compounds in high yields in a variety of solvents, preferentially acetone.The reagent is highly selective.Thus, oxidation of primary alcohols gives aldehydes as the exclusive products.KCC is less useful for the transformation of primary saturated and homoallylic alcohols.Double bonds are susceptible to isomerization under the reaction conditions employed; for example, oxidati on of pure nerol yields citral, and pulegol is converted to a mixture of pulegone and isopulegone.Oxidation of tertiary allylic alcohols may give the transposed aldehyde.Thus, linalool is converted to citral in high yield.
- Carlsen, Per H.J.,Braenden, Jon Eric
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p. 313 - 317
(2007/10/02)
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- A MILD HYDROGENOLYTIC-HYDROLYTIC CONVERSION OF OXIMES TO CARBONYL COMPOUNDS.
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Oximes are converted into the corresponding carbonyl compounds in high yields using Raney-nickel and sodium hypophosphite at pH 5.
- Monti, D.,Gramatica, P.,Speranza, G.,Tagliapietra, S.,Manitto, P.
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p. 803 - 808
(2007/10/02)
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- PALLADIUM CATALYZED OXIDATION OF Δ2, Δ3, AND Δ4-UNSATURATED ALCOHOLS
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Palladium (0.63 molpercent) catalyzes the oxidation of Δ2, Δ3, and Δ4-unsaturated alcohols to the corresponding ketones in good yields, where bromomesitylene or bromobenzene is used as an oxidant.
- Tamaru, Yoshinao,Inoue, Kenji,Yamada, Yoshimi,Yoshida, Zen-ichi
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p. 1801 - 1802
(2007/10/02)
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- A NOVEL METHOD FOR THE TERPENE SYNTHESIS BY THE RING-OPENING REACTION OF β-METHYL-β-PROPIOLACTONE
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A new route for the terpene synthesis is investigated, which undergoes via terpene carboxylic acids as key intermediates obtained by the regiospecific ring opening of β-methyl-β-propiolactone with cuprate or with a Grignard reagent in the presence of a copper catalyst.
- Fujisawa, Tamotsu,Sato, Toshio,Kawara, Tatsuo,Noda, Atsunari,Obinata,Toshiyuki
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p. 2553 - 2554
(2007/10/02)
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- A novel synthetic method for optically active terpenes by the ring-opening reaction of (R)-(+)-β-methyl-β-propiolactone
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Optically active terpene such as (R)-(+)-citronellol, (R)-(+)-pulegone or (S)-ar-turmerone is prepared in high enantiomeric excess from an intermediate, (R)-(+)-citronellic acid or (S)-(+)-3-p-tolylbutyric acid, which is easily prepared by the Sn2 type of ring opening reaction of (R)-(+)-β-methyl-β-propiolactone with homoprenylmagnesium bromide in the presence of a copper(I) salt or di-p-tolylcuprate.
- Sato, Toshio,Kawara, Tatsuo,Nishizawa, Akira,Fujisawa, Tamotsu
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p. 3377 - 3380
(2007/10/02)
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