- Green diacetoxylation of alkenes in a microchemical system
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The palladium-catalyzed diacetoxylation and trifluoromethanesulfonic acid-catalyzed diacetoxylation using inexpensive and environmentally friendly hydrogen peroxide and peracetic acid were successfully conducted with the help of microchemical technology.
- Park, Jeong Hyeon,Park, Chan Yi,Song, Hyun Seung,Huh, Yun Suk,Kim, Geon Hee,Park, Chan Pil
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supporting information
p. 752 - 755
(2013/04/10)
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- Triflic acid catalyzed oxidative lactonization and diacetoxylation of alkenes using peroxyacids as oxidants
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A clean and efficient diacetoxylation reaction of alkenes catalyzed by triflic acid using commercially available peroxyacids as the oxidants has been developed. This method was also applied in oxidative lactonizations of unsaturated carboxylic acids in good to high yields.
- Kang, Yan-Biao,Gade, Lutz H.
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experimental part
p. 1610 - 1615
(2012/04/04)
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- The nature of the catalytically active species in olefin dioxygenation with PhI(OAc)2: Metal or proton?
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Evidence for the protiocatalytic nature of the diacetoxylation of alkenes using PhI(OAc)2 as oxidant is presented. Systematic studies into the catalytic activity in the presence of proton-trapping and metal-complexing agents indicate that protons act as catalysts in the reaction. Using triflic acid as catalyst, the selectivity and reaction rate of the conversion is similar or superior to most efficient metal-based catalysts. Metal cations, such as Pd(II) and Cu(II), may interact with the oxidant in the initiation phase of the catalytic transformation; however, 1 equiv of strong acid is produced in the first cycle which then functions as the active catalyst. Based on a kinetic study as well as in situ mass spectrometry, a mechanistic cycle for the proton-catalyzed reaction, which is consistent with all experimental data presented in this work, is proposed.
- Kang, Yan-Biao,Gade, Lutz H.
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p. 3658 - 3667
(2011/05/03)
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- Efficient diacetoxylation of alkenes via Pd(II)/Pd(IV) process with peracetic acid and acetic anhydride
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A palladium-catalyzed diacetoxylation of alkenes in the presence of peracetic acid and acetic anhydride was developed to produce diacetates efficiently and diastereoselectively. Due to its mild conditions, this method was suitable for a broad range of substrates encompassing conjugated and nonconjugated olefins.
- Park, Chan Pil,Lee, Joo Ho,Yoo, Kyung Soo,Jung, Kyung Woon
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supporting information; experimental part
p. 2450 - 2452
(2010/07/05)
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- Copper-catalyzed diacetoxylation of olefins using PhI(OAc)2 as oxidant
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(Figure Presented) Copper(I) or -(II) salts with weakly coordinating anions catalyze the diacetoxylation of olefins efficiently In the presence of PhI(OAc)2 as the oxidant under mild conditions. The reaction is effective for aryl, aryl alkyl, as well as aliphatic terminal and internal olefins forming the corresponding vicinal diacetoxy compounds In 70-85% yields and dr (syn/anti) of up to 5.2. Under these conditions, homoallylic alcohols formed the corresponding tetrahydrofuran derivatives in high yields.
- Seayad, Jayasree,Seayad, Abdul Majeed,Chai, Christina L. L.
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supporting information; experimental part
p. 1412 - 1415
(2010/06/13)
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- Influence of α-methyl substitution of proline-based organocatalysts on the asymmetric α-oxidation of aldehydes
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The direct asymmetric organocatalytic α-oxidation of aldehydes using trans-2-(p-methylphenylsulfonyl)-3-phenyloxaziridine is reported. This method affords the S isomer of α-hydroxy aldehydes, thereby complementing the selectivity for the R isomer observed using the two-step nitrosobenzene method. Use of α-methylproline and α-methylproline tetrazole significantly increases the enantioselectivity observed for the α-oxidation of aldehydes compared to analogous unsubstituted organocatalysts.
- Tong, Sok-Teng (Amy),Brimble, Margaret A.,Barker, David
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experimental part
p. 4801 - 4807
(2009/10/09)
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- Palladium-catalyzed olefin dioxygenation
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A general method for the vicinal dioxygenation of olefins was developed using cationic Pd diphosphine complexes as the catalysts and PhI(OAc)2 as the terminal oxidant. In comparison to known Pd-catalyzed vicinal oxidations, this method is suitable for a broad range of olefins in both inter- and intramolecular reactions. An 18O-labeling experiment provides insight into the mechanism of this transformation which presumably involves Pd(II)/Pd(IV) intermediates. Copyright
- Li, Yang,Song, Datong,Dong, Vy M.
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p. 2962 - 2964
(2008/09/20)
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- The highly enantioselective transformation of silylketenes into α-silylthioesters catalysed by cinchona alkaloids
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The reaction of silylketenes with thiophenol, mediated by cinchona alkaloid catalysts, proceeds to give α-silylthioester products in good chemical yield and with enantiomeric excess values in the range 79-93%. The absolute configuration of one of the thioester products was determined by X-ray diffraction.
- Blake, Alexander J.,Friend, Christopher L.,Outram, Robert J.,Simpkins, Nigel S.,Whitehead, Andrew J.
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p. 2877 - 2881
(2007/10/03)
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- Kinetic resolution of 2-acylated-1,2-diols by lipase-catalyzed enantiomer selective acylation
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Enantiomer selectivity of lipase catalyzed acylation of 2-acylated 1,2-diols was studied. First, acylation of 2-acetoxyheptan-1-ol rac-3b with vinyl acetate was investigated by varying the enzymes and the solvent, showing the highest enantiomer selectivity by using lipase from Pseudomonas fluorescens (PfL) in hexane-vinyl acetate (VA). We have found varying or even reversed enantiomer selectivity for different secondary acyl moieties in 2-acyloxyheptan-1-ols rac-3bA-F. Next, all six possible types of enantiomer selective biotransformations (hydrolysis of diacetate and the two kinds of monoacetetes; acylation of diol and the two kinds of monoacetates) were compared on two model diols rac-4b,d. Among the transformations investigated, acetylation of secondary monoacetates rac-3b,d showed the highest enantiomer selectivity. Finally, PfL catalyzed acetylations of several 2-acetylated 1,2-diols rac-3a-g were investigated under our optimum conditions.
- Egri, Gabriella,Baitz-Gacs, Eszter,Poppe, Laszlo
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p. 1437 - 1448
(2007/10/03)
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- The chemistry of the blue stain fungi. Part 1. Some metabolites of Ceratocystis species associated with mountain pine beetle infected lodgepole pine
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Metabolites formed in still culture by Ceratocystis clavigera, C. ips, and C. huntii, three of the four Ceratocystis species associated with the blue stain disease of pine, have been identified.In addition to the ubiquitous fungal metabolites ergosterol, ergosterol peroxide, and fatty acids we have isolated succinic acid, β-phenethyl alcohol (1), tryptophol (2), prolylleucyl anhydride (3), tyrosol (4), 3-phenylpropane-1,2-diol (5), 6,8-dihydroxy-3-methylisocoumarin (8), 6,8-dihydroxy-3-hydroxymethylisocoumarin (9), p-hydroxybenzaldehyde (10), phenylacetic acid (11), p-hydroxyphenylacetic acid (12), phenyllactic acid (13), p-hydroxyphenyllactic acid (14), and 2,3-dihydroxybenzoic acid (15).The complex formed by chelation of iron with 2,3-dihydroxybenzoic acid may be responsible, at least in part, for the blue staining of the sapwood of diseased pine.
- Ayer, William A.,Browne, Lois M.,Feng, Meow-Chen,Orszanska, Helena,Saeedi-Ghomi, Hossein
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p. 904 - 909
(2007/10/02)
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- Synthesis of 2-(S)-Benzoyloxirane
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Hydrogenolysis of D-erythro-1-C-phenylglyceryl triacetate (3) prepared from D-erythro-1-C-phenylglycerol (2) furnishes (S)-1,2-diacetoxy-3-phenylpropane (4) which is saponified to give (S)-3-phenyl-1,2-propanediol (5).The transformation of 5 to 2-(S)-benz
- Sanghvi, Y. S.,Dabral, V.,Rao, A. S.
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- PREPARATION OF 1,3-DIOLS BY METALATION-HYDROBORATION OF ALKYNES A 1,2-HYDROGEN MIGRATION FROM BORON TO CARBON
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Metalation of a series of 1- and 2-alkynes with subsequent treatment with diborane and oxidation gave 1,3-diols exclusively.Deuteroboration of the lithiated acetylenes established the occurrence of a displacement of one of the B atoms by deuterium in gem-diboronated compounds.Hydroboration of several acetylenes and acetylides was also studied.
- Medlik-Balan, A.,Klein, J.
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p. 299 - 304
(2007/10/02)
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