- Biomimetic conversion of α-pinene with H2O2 to sobrerol over V2O5: Dihydroxylation by a peroxo vanadium peracid vectoring gentle synergistic oxidation
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In this communication, we report the gentle preparation of sobrerol from dihydroxylation of α-pinene synergistically catalyzed by V2O5-H2O2 under benign conditions. It was proposed that a “peroxo vanadium acid”, VVO(OH)(OOH), was formed by HOO? insertion and proton transfer between V2O5 and H2O2. Theoretical DFT calculations that using the dimer?vanadium peracid as a model of the catalytically active species revealed that peroxo vanadium acid exhibited bifunctional catalytic capabilities resembling epoxidation of α-pinene by peracetic acid and then open-ring hydration with an acetic media.
- He, Huiting,Huang, Geng,Kirk, Steven Robert,Li, Hui,Liu, Jian,Liu, Qiang,Liu, Xianxiang,Mao, Liqiu,Su, Shengpei,Xu, Qiong,Yin, Dulin
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- Hot water-promoted SN1 solvolysis reactions of allylic and benzylic alcohols
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During the studies of hydrolysis of epoxides in water, we found that the hydrolysis of (-)-α-pinene oxide at 20 °C gave enantiomerically pure trans-(-)-sobrerol, whereas the same reaction in water heated at reflux unexpectedly gave a racemic mixture of trans- and cis-sobrerol (trans/cis=6:4). We have examined this remarkable difference in detail and found that hot water, whose behavior is quite different compared with room- or high-temperature water, could promote SN1 solvolysis reactions of allylic alcohols and thus caused the racemization of trans-(-)-sobrerol. The effect of reaction temperature, the addition of organic co-solvent, and the concentration of the solute on the rate of the racemization of trans-(-)-sobrerol were further examined to understand the role that hot water played in the reaction. It was proposed that the catalytic effects of hot water are owing to its mild acidic characteristic, thermal activation, high ionizing power, and better solubility of organic reactant. Further investigation showed that the racemization of other chiral allylic/benzylic alcohols could efficiently proceed in hot water.
- Xu, Zhao-Bing,Qu, Jin
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p. 314 - 323
(2013/03/13)
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- Unique salt effect on highly selective synthesis of acid-labile terpene and styrene oxides with a tungsten/Hcatalytic system under acidic aqueous conditions
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Acid-labile epoxides such as terpene and styrene oxides are effectively synthesized in high yields with good selectivities using tungsten-catalyzed hydrogen peroxide epoxidation in the presence of NaO The salt effect is thought to originate with the addition of a saturated amount of NaOto aqueous H this addition strongly inhibited the undesired hydrolysis of the acid-labile epoxy products, despite the biphasic conditions of substrate as oil phase and Has acidic aqueous phase.
- Hachiya, Houjin,Kon, Yoshihiro,Ono, Yutaka,Takumi, Kiyoshi,Sasagawa, Naoki,Ezaki, Yoichiro,Sato, Kazuhiko
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experimental part
p. 1672 - 1678
(2012/07/16)
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- Unique salt effect on the high yield synthesis of acid-labile terpene oxides using hydrogen peroxide under acidic aqueous conditions
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Acid-labile epoxides such as -pinene oxide are (effectively) synthesized in high yield from the epoxidation of terpenes with aqueous H2O 2 catalyzed by Na2WO4, [Me(n-C 8H17)3N]HSO4, and PhP(O)(OH) 2 in the presence of Na2SO4 as an auxiliary additive under organic solvent-free conditions at ambient temperature. Origin of the salt effect is considered that the addition of a saturated amount of Na2SO4 to aqueous H2O2 strongly inhibited the undesired hydrolysis of the acid-labile epoxide products, despite the highly acidic reaction conditions. Georg Thieme Verlag Stuttgart · New York.
- Hachiya, Houjin,Kon, Yoshihiro,Ono, Yutaka,Takumi, Kiyoshi,Sasagawa, Naoki,Ezaki, Yoichiro,Sato, Kazuhiko
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scheme or table
p. 2819 - 2822
(2012/01/02)
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- Comparative autoxidation of 3-Carene and α-Pinene: Factors governing regioselective hydrogen abstraction reactions
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Autoxidation reactions of 3-Carene 1 and α-Pinene 2 were performed using various homogeneous catalysts. Different product and regio- selectivities were observed. The factors that promote hydrogen abstraction (HA) reactions in both molecules are discussed, and it is proposed that the difference in the product selectivities is due to the lack of 'cyclic activation' in 2. Oxidation of 1 produced mainly 3-carene-5-one 3, while 2 yielded 2,3-epoxypinane 6 as the major product.
- Rothenberg, Gadi,Yatziv, Yael,Sasson, Yoel
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p. 593 - 598
(2007/10/03)
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- Pheromone Synthesis, CIV.- Synthesis of the Enantiomers of α-Phellandren-8-ol (p-Mentha-1,5-dien-8-ol), a Monoterpene from Bark Beetles
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Enantiomerically pure (R)-α-phellandren-8-ol (p-mentha-1,5-dien-8-ol, 1a) was synthesized from (R)-carvone (2).Similarly (S)-1a was synthesized from (S)-2.
- Mori, Kenji,Igarashi, Yasuhiro
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- THE STEREOSPECIFIC HYDROXILATION OF ENDOCYCLIC ETHYLENIC LINKAGE IN THE BIOTRANSFORMATION OF α- TERPINYL ACETATE WITH CULTURED SUSPENSION CELLS OF NICOTIANA TABACUM
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The biotransformation of (+/-)-8-acetoxy-p-menth-1-ene (α-terpinyl acetate) with the cultured cells of Nicotiana tabacum was found to result in the predominant formation of 8-acetoxy-c-4-p-menthane-r-1, t-2-diol.This experimental result indicates that the hydroxylation of the endocyclic ethylenic linkage with the cultured suspension cells is stereospecific.
- Hirata, Toshifumi,Lee, Ym Sook,Suga, Takayuki
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p. 671 - 674
(2007/10/02)
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