- 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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- 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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- α′-hydroxy-α,β-unsaturated tosylhydrazones: Preparation and use as intermediates for carbonyl and enone transpositions
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Regiospecifically generated α,β-unsaturated tosylhydrazones dianions are treated with molecular oxygen, yielding α′-hydroxy-α,β-unsaturated tosylhydrazones, versatile intermediates for organic synthesis. They proved to be useful for 1,2-carbonyl and 1,2-enone transpositions, and also permitted the preparation of α′-hydroxy enones in very high yields.
- Baptistella, Lucia H. B.,Aleixo, Adriana M.
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p. 2937 - 2950
(2007/10/03)
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- Thermal degradation of terpenes: Camphene, Δ3-carene, limonene, and α-terpinene
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Emissions from wood dryers have been of some concern for a number of years, and recent policy changes by the Environmental Protection Agency have placed emphasis upon the gaseous emissions that lead to the formation of particulate matter as small as 2.5 μm diameter. In this qualitative study, camphene, Δ3-carene, limonene, and α-terpinene were thermally degraded in the presence of air to determine the number and kind of oxidative degradation products that might be expected under drying conditions used in processing wood products. Various chromatographic methods were used to isolate the products for proof of structure by NMR and/or GC-MS. The degradation products resulted from dehydrogenations, epoxidations, double bond cleavages, allylic oxidations, and rearrangements. A number of compounds not previously associated with the thermal degradation of these terpenes were identified. Emissions from wood dryers have been of some concern for a number of years, and recent policy changes by the Environmental Protection Agency have placed emphasis upon the gaseous emissions that lead to the formation of particulate matter as small as 2.5 μm diameter. In this qualitative study, camphene, Δ3-carene, limonene, and α-terpinene were thermally degraded in the presence of air to determine the number and kind of oxidative degradation products that might be expected under drying conditions used in processing wood products. Various chromatographic methods were used to isolate the products for proof of structure by NMR and/or GC-MS. The degradation products resulted from dehydrogenations, epoxidations, double bond cleavages, allylic oxidations, and rearrangements. A number of compounds not previously associated with the thermal degradation of these terpenes were identified.
- Mcgraw, Gerald W.,Hemingway, Richard W.,Ingram Jr., Leonard L.,Canady, Catherine S.,Mcgraw, William B.
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p. 4029 - 4033
(2007/10/03)
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- Transformation of a monoterpene ketone, (R)-(+)-pulegone, a potent hepatotoxin, in Mucor piriformis
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Biotransformation of a monoterpene ketone, (R)-(+)-pulegone (I), a potent hepatotoxin, was studied using a fungal strain, Mucor piriformis. Eight metabolites, namely, 5-hydroxypulegone (II), piperitenone (III), 6- hydroxypulegone (IV), 3-hydroxypulegone (V), 5-methyl-2-(1-hydroxy-1- methylethyl)-2-cyclohexene-1-one (VI), 3-hydroxyisopulegone (VII), 7- hydroxypiperitenone (VIII), and 7-hydroxypulegone (IX), have been isolated from the fermentation medium and identified. GC analysis of the metabolites indicated that II was the major metabolite formed. The organism initiates transformation either by hydroxylation at the C-5 position or by hydroxylation of the ring methylenes, the former being the major activity. On the basis of the identification of the metabolites, pathways for the biotransformation of (R)-(+)-pulegone have been proposed. The mode of transformation of (S)-(-)-pulegone by this organism was shown to be similar to that of its (R)-(+)-enantiomer. When isopulegone (X) was used as the substrate, the organism isomerized it to pulegone (I), which was then transformed to metabolites II-IX.
- Madyastha,Thulasiram
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p. 1203 - 1207
(2007/10/03)
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- β-Pinene-6-one: A pivotal synthetic intermediate
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Submitting the title ketone to either acetoxymercuration or basic conditions resulted in the formation of the acid β-5 and α-5, respectively, with an useful selectivity, related rearrangements being observed by using the corresponding alcohol and its epoxy derivative.
- Hebrault,Uguen
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p. 6699 - 6702
(2007/10/03)
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- Biotransformation Products of (5R)-(+)-Pulegone and (2S,5R)-(-)-Menthone Produced by Cultured Cells of Catharanthus roseus
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Catharanthus roseus cultured cells produce several new oxidized products from (5R)-(+)-pulegone and (2S, 5R)-(-)-menthone, in some of which a double bond migration has occurred. Products were identified using NMR and mass spectrometry. The pleasant fragrances of some of the products suggest possible use as perfumery agents.
- Williams, Howard J.,Moyna, Guillermo,Scott, A. Ian,Hamada, Hiroki,Lwin, War War,Tanaka, Toshinori,Furuya, Tsutomu
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p. 838 - 840
(2007/10/03)
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- Biotransformation of terpenic compounds by fungi. I. Metabolism of R-(+)-pulegone
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R-(+)-Pulegone 1 is converted by several fungal strains to new regioselectively hydroxylated compounds. Epoxidation of the double bond does not seem to be responsible for the main observed hydroxylation pattern.
- Ismaili-Alaoui,Benjilali,Buisson,Azerad
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p. 2349 - 2352
(2007/10/02)
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- Regiospecific Functionalization of the Monoterpene Ether 1,3,3-Trimethyl-2-oxabicyclooctane (1,8-Cineole). Synthesis of the Useful Bridged γ-Lactone 1,3-Dimethyl-2-oxabicyclooctan-3-->5-olide
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The regiospecific functionalization at C-5 and difuctionalization at C-5/C-8 and C-5/C-10 of the monoterpene 1,3,3-trimethyl-2-oxabicyclooctane (1) is described.Chromyl acetate oxidation of 1 afforded 1,3,3-trimethyl-2-oxabicyclooctan-5-one (6) in 60percent yield along with 28percent of unreacted 1 and minor amounts of exo-1,3,3-trimethyl-2-oxabicyclooctan-5-ol acetate (9), 1,3,3-trimethyl-2-oxabicyclooctane-5,8-dione (13), exo-8-acetoxy-1,3,3-trimethyl-2-oxabicyclooctan-5-one (16), 1,3,3-trimethyl-2-oxabicyclooctane-5,7-dione (14), and orcinol (15).On digestion with oxalic or phthalic acid, ketone 6 was converted into a mixture of piperitenone (20), 3-methyl-2-cyclohexenone (22), acetone, and traces of isopiperitenone (21), while 60percent sulfuric acid at room temperature yielded 20 as the sole reaction product.Oxidation of 6 with chromyl acetate yielded diketone 13, which decomposed into orcinol (15) on digestion with either boiling water or a 2.5percent sodium bicarbonate solution.Sodium borohydride or lithium aluminum hydride reduction of 6 gave stereospecifically exo-1,3,3-trimethyl-2-oxabicyclooctan-5-ol (7) while reduction with sodium-ethanol or aluminum isopropoxide in isopropyl alcohol (equilibrium conditions) yielded a 3:2 mixture of the alcohols 7 and 8, respectively.Treatment of 7 with phosphoryl chloride produced 1,3,3-trimethyl-2-oxatricyclo5,8>octane (25) together with minor amounts of the chlorocineoles 10 and 11.Pyrolysis of the methyl xanthate of 7 yielded 1,3,3-trimethyl-2-oxabicyclooct-5-ene (2).Photolysis of 7 in the presence of mercuric oxide and iodine or iodosylbenzene diacetate and iodine gave the tricyclic diether 29, which was quantitatively converted into the bridged γ-lactone 30 by oxidation with ruthenium tetraoxide.Oxidation of 29 with chromyl acetate yielded a 1:1 mixture of 30 and the formate lactone 31.Lithium aluminum hydride reduction of 30 produced diol 37, which was converted into menthofuran (44) in five steps.
- Boggiatto, Margarita V. de,Heluani, Carola S. de,Fenik, Ines J. S.,Catalan, Cesar A. N.
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p. 1505 - 1511
(2007/10/02)
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- Synthesis of Terpenes Containing the Bicycloheptane Ring System by the Intramolecular Cycloaddition Reaction of Vinylketenes with Alkenes. Preparation of Chrysanthenone, β-Pinene, β-cis-Bergamotene, β-trans-Bergamotene, β-Copaene, and β-Ylangene and Lemnalol
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Treatment of geranoyl chloride (20) with triethylamine in toluene at reflux gave the vinylketene 21 which underwent a cycloaddition to give 7,7-dimethyl-2-methylenebicycloheptan-6-one (24) in 43percent yield.Isomerization over Pd gave chrysanthenone (6) in quantitative yield.Wolf-Kischner reduction gave β-pinene (5) in 70percent yield.A similar sequence of reactions starting from (Z,E)- and (E,E)-farnesoyl chloride gave ketones 51 and 57, which were converted to β-cis-bergamotene (8) and β-trans-bergamotene (9), respectively. β-Copaene (10) and β-ylangene (11) were prepared from 57 by a three-step sequence.Treatment of the imidazole 59 with tri-n-butyltin hydride in toluene at reflux gave a 46percent yield of a 1:1 mixture of 10 and 11.Selenium dioxide oxidation of 11 gave the antitumor agent lemnalol.The mechanisms of the regiospecific ketene generation and the cycloaddition reaction have been explored, and the reactivity of the novel bicycloheptanones has been examined.
- Kulkarni, Yashwant S.,Niwa, Maho,Ron, Eyal,Snider, Barry B.
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p. 1568 - 1576
(2007/10/02)
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- Photochemical Transformationos of Protonated Phenols. A One-Step Synthesis of Umbellulone from Thymol
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UV irradiation of thymol (7) at 254 or 300 nm in trifluoromethanesulfonic acid affords ten products, eight of which have been isolated and characterized.Four competitive processes are suggested to be operating in the formation of the photoproducts: (i) regioselective type A rearrangement leading to umbellulone (8, about 10percent, (ii) formal C2->C3 migration by type A rearrangement and ring opening which affords the principal products, 3-isopropyl-5-methylphenol (12, 17percent), (iii) intermolecular transalkylation leading to diisopropylphenols 13-15 (17percent), and (iv) formation ofpiperitenone (10, 5percent) initiated by hydrogen abstraction.A mechanism for the formation of 10 is proposed.Both para- and ortho-protonated 7 are suggested to be involved in product formation.
- Baeckstroem, Peter,Jacobsson, Ulla,Koutek, Bohumir,Norin, Torbjoern
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p. 3728 - 3732
(2007/10/02)
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- NOVEL SYNTHETIC METHOD FOR PIPERITENONES THROUGH DIELS-ALDER REACTION
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The Diels-Alder adduct obtained from 1-(2-phenylselenoethoxy)isoprene and methyl vinyl ketone was applied to synthesis of piperitenones.
- Mandai, Tadakatsu,Osaka, Kazuhito,Kawagishi, Makoto,Kawada, Mikio,Otera, Junzo
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p. 797 - 804
(2007/10/02)
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- Bicyclic hindered amino acids, metal salts thereof and stabilized compositions
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Compounds having the formula STR1 wherein R is alkylene, M is hydrogen or a metal, and m has a value of from 1 to 4, Are good light stabilizers. The amino acids may be formed, for example, from 1,3,3-trimethyl-3-azabicyclo[2.2.2]octane-5-ol and sebacic acid to give o-mono(1,3,3-trimethyl-2-azabicyclo[2.2.2]octane-5-ol)sebacate. The metal salts of the acids are readily prepared by reacting the acids or their salts with a reactive form of the metal or metal complex.
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- Manufacture of d,l-methol
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Manufacture of piperitenone by mixing excess mesityl oxide with 10 to 70% by weight aqueous potassium hydroxide solution, heating the mixture to a temperature of between 20°C and the boiling point and introducing the methyl vinyl ketone into the heated mixture. d,1-methol is obtained directly, or via a mixture of methone and isomenthone, from the piperitenone which is obtained in good yield.
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- Production of piperitenone
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A process for the production of piperitenone by heating 3,3-dimethylacrolein in the presence of an acid. Piperitenone is a valuable intermediate for the synthesis of menthol which is much sought after for cosmetic and pharmaceutical purposes.
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