- Electron-transfer reduction of selected alcohols with alkalide K-, K+(15-crown-5)2 via organometallic intermediates
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The course of the reaction of alkalide K-, K+ (15-crown-5)2 1 with selected alcohols depends on the kind of alcohol and the mode of substrate delivery. In the case of methanol, potassium methoxide formed initially undergoes destructfion at the excess of 1. It results in potassium oxide and methylpotassium. The latter opens the crown ether ring giving potassium tetraethylene glycoxide vinyl ether and methane. A similar course of the process is observed for propanol. Potassium glycidoxide is the main product formed in the reaction of 1 with glycidol. Its oxirane ring is opened at the excess of 1. Organopotassium alkoxides, i.e., potassium potassiomethoxide and dipotassium potassiopropane-1,2-dioxide are intermediate products of this reaction. They react then with the crown ether. Potassium methoxide, potassium enolate of acetaldehyde, dipotassium propane-1, 2-dioxide and potassium tetraethylene glycoxide vinyl ether are the final products of this process.
- Grobelny, Zbigniew,Stolarzewicz, Andrzej,Maercker, Adalbert,Krompiec, Stanis,Kasperczyk, Janusz,Rzepa, Józef,Frey, Holger
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Read Online
- A Chiral Copper Catalyzed Site-Selective O-Alkylation of Carbohydrates
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Highly regioselective alkylation of sugar hydroxyl groups has always been an important challenge in carbohydrate chemistry, especially for the selective alkylation of trans diols, there is no direct and efficient catalytic method so far. A chiral copper c
- Ren, Bo,Wang, Jiaxi,Zhang, Mengyao,Chen, Yue,Zhao, Wei
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supporting information
p. 665 - 670
(2021/12/02)
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- Hydrogen bonding-catalysed alcoholysis of propylene oxide at room temperature
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Alcoholysis of propylene oxide (PO) is achieved over azolate ionic liquids (IL,e.g., 1-hydroxyethyl-3-methyl imidazolium imidazolate) at room temperature, accessing glycol ethers in high yields with excellent selectivity (e.g., >99%). Mechanism investigation indicates that cooperation of hydrogen-bonding of the anion with methanol and that of the cation with PO catalyses the reaction.
- Li, Ruipeng,Liu, Zhimin,Wang, Yuepeng,Xiang, Junfeng,Xu, Yueting,Zhang, Fengtao,Zhao, Yanfei
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supporting information
p. 8734 - 8737
(2021/09/08)
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- Benzoxaborole Catalyst for Site-Selective Modification of Polyols
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The site-selective modification of polyols bearing several hydroxyl groups without the use of protecting groups remains a significant challenge in synthetic chemistry. To address this problem, novel benzoxaborole derivatives were designed as efficient catalysts for the highly site-selective and protecting-group-free modification of polyols. To identify the effective substituent groups enhancing the catalytic activity and selectivity, a series of benzoxaborole catalysts 1a–k were synthesized. In-depth analysis for the substituent effect revealed that 1i–k, bearing multiple electron-withdrawing fluoro- and trifluoromethyl groups, exhibited the greatest catalytic activity and selectivity. Moreover, 1i-catalyzed benzoylation, tosylation, benzylation, and glycosylation of various cis-1,2-diol derivatives proceeded with good yield and site-selective manner.
- Kusano, Shuhei,Miyamoto, Shoto,Matsuoka, Aki,Yamada, Yuji,Ishikawa, Ryuta,Hayashida, Osamu
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supporting information
p. 1598 - 1602
(2020/02/11)
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- Regio/site-selective alkylation of substrates containing a: Cis -, 1,2- or 1,3-diol with ferric chloride and dipivaloylmethane as the catalytic system
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In this study, we reported the regio/site-selective alkylation of substrates containing a cis-, 1,2- or 1,3-diol with FeCl3 as a key catalyst. A catalytic system consisting of FeCl3 (0.01-0.1 equiv.) and dipivaloylmethane (FeCl3/dipivaloylmethane = 1/2) was used to catalyze the alkylation in the presence of a base. The produced selectivities and isolated yields were similar to those obtained by methods using the same amount of FeL3 (L = acylacetone ligand) as the catalyst in most cases. The previously reported FeL3 catalysts for alkylation are not commercially available and have to be synthesized prior to use. In contrast, FeCl3 and dipivaloylmethane (Hdipm) are very common and inexpensive nontoxic reagents in the lab, thereby making the method much greener and easier to handle. Mechanism studies confirmed for the first time that FeCl3 initially reacts with two equivalents of Hdipm to form [Fe(dipm)3] in the presence of a base in acetonitrile, followed by the formation of a five or six-membered ring intermediate between [Fe(dipm)3] and two hydroxyl groups of the substrate. A subsequent reaction between the cyclic intermediate and the alkylating agent results in selective alkylation of the substrate.
- Lv, Jian,Liu, Yu,Zhu, Jia-Jia,Zou, Dapeng,Dong, Hai
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supporting information
p. 1139 - 1144
(2020/03/11)
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- Ruthenium-Catalyzed Selective Hydrogenation of Epoxides to Secondary Alcohols
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A ruthenium(II)-catalyzed highly selective Markovnikov hydrogenation of terminal epoxides to secondary alcohols is reported. Diverse substitutions on the aryl ring of styrene oxides are tolerated. Benzylic, glycidyl, and aliphatic epoxides as well as diepoxides also underwent facile hydrogenation to provide secondary alcohols with exclusive selectivity. Metal-ligand cooperation-mediated ruthenium trans-dihydride formation and its reaction involving oxygen and the less substituted terminal carbon of the epoxide is envisaged for the origin of the observed selectivity.
- Thiyagarajan, Subramanian,Gunanathan, Chidambaram
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supporting information
p. 9774 - 9778
(2019/12/02)
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- IRAK DEGRADERS AND USES THEREOF
-
The present invention provides compounds, compositions thereof, and methods of using the same.
- -
-
Paragraph 2284; 2285
(2019/07/10)
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- Double-hetero atom six-membered ring of synthetic method
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The invention provides a double-hetero atom six-membered ring of synthetic method. The synthetic method comprises to alkyl substituted cyclopropane and benzyl alcohol and/or a the oxygen radical animal pen is mellow as the starting material, sequentially carry out the ring-opening reaction, a transesterification reaction, 1st sulfonylation reaction, alcoholysis reaction and the nucleophilic substitution reaction, catalytic hydrogenation reaction and 2nd sulfonylation reaction and forming ring reaction, to obtain the required double-hetero atom six-membered ring, a formula (1) of the structure shown. In order to price the comparatively cheap racemic alkyl substituted cyclopropane as raw materials, to participate in the ring-opening reaction, to obtain a ring opening product. Then under the action of the esterase, make the ring-opening products which is a transesterification reaction, disposable obtain the desired racemic compound. This avoids the traditional method of multi-step separation and purification in the synthesis step, shortens the synthetic route. In the above synthetic route also avoids the need to use some dangerous reagent, process more security, reducing waste generation, and save the process cost.
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Paragraph 0110; 0114; 0115; 0116; 0117
(2018/07/30)
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- Piers' borane-mediated hydrosilylation of epoxides and cyclic ethers
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We report the first diarylborane-catalysed hydrosilylation of epoxides and cyclic ethers. Mechanistic studies on the in situ generated Piers' borane (C6F5)2BH with hydrosilanes in the presence of an epoxide revealed that an alkyloxy(diaryl)borane (C6F5)2BOR is readily formed as a catalytically competent species for the outer-sphere hydrosilylation of epoxides and cyclic ethers.
- Zhang, Jianbo,Park, Sehoon,Chang, Sukbok
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supporting information
p. 7243 - 7246
(2018/07/05)
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- Regioselective alkylation of carbohydrates and diols: A cheaper iron catalyst, new applications and mechanism
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As an extension of our previous research on the regioselective protection of carbohydrates and diols, we developed an iron catalyst, Fe(dibm)3 (dibm = diisobutyrylmethane), which has an unusually broad catalytic scope in the selective monoalkyl
- Ren, Bo,Yan, Ningning,Gan, Lu
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p. 46257 - 46262
(2017/10/11)
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- Highly Efficient Selective Benzylation of Carbohydrates Catalyzed by Iron(III) with Silver Oxide and Bromide Anion as Co-catalysts
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A highly efficient, green, and regioselective method for the benzylation of diols and polyols was developed. With the use of Ag2O (0.6 equiv.) and tetrabutylammonium bromide (0.1 equiv.) as co-catalysts, the iron(III)-catalyzed benzylation reaction proceeded to completion at 40 °C within 2–3 h and gave the products in high yields with high regioselectivities. A mechanism involving the principle of enhanced basicity of Ag2O by soft anions was proposed.
- Ren, Bo,Lv, Jian,Zhang, Yu,Tian, Jun,Dong, Hai
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p. 950 - 953
(2017/03/27)
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- Selective hydrogenation of arenes to cyclohexanes in water catalyzed by chitin-supported ruthenium nanoparticles
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The selective hydrogenation of aromatic compounds to cyclohexanes was found to be promoted by chitin-supported ruthenium nanoparticles (Ru/chitin) under near-neutral, aqueous conditions without the loss of C-O/C-N linkages at benzylic positions.
- Morioka, Yuna,Matsuoka, Aki,Binder, Kellie,Knappett, Benjamin R.,Wheatley, Andrew E.H.,Naka, Hiroshi
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p. 5801 - 5805
(2016/08/06)
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- Epoxide hydrolysis and alcoholysis reactions over crystalline Mo-V-O oxide
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Crystalline Mo-V-O oxides have been used as a catalyst for the hydrolysis and alcoholysis of propylene oxide to diols and ethers, respectively. Relationships between the active crystal facet, the acidity of Mo-V-O catalysts and the activity have been established. Our results indicate that the a-b plane is the active facet for the hydrolysis reaction.
- Zhang, Xiaochen,Wang, Min,Zhang, Chaofeng,Lu, Jianmin,Wang, Yehong,Wang, Feng
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p. 70842 - 70847
(2016/08/05)
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- An Iron(III) Catalyst with Unusually Broad Substrate Scope in Regioselective Alkylation of Diols and Polyols
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In this study, [Fe(dibm)3] (dibm=diisobutyrylmethane) is shown to have unusually broad scope as a catalyst for the selective monoalkylation of a diverse set of 1,2- and 1,3-diol-containing structures. The mechanism is proposed to proceed via a cyclic dioxolane-type intermediate, formed between the iron(III) species and two adjacent hydroxyl groups. This approach represents the first transition-metal catalysts that are able to replace stoichiometric amounts of organotin reagents in regioselective alkylation. The reactions generally lead to very high regioselectivities and high yields, on par with, or better than, previous methods used for regioselective alkylation.
- Ren, Bo,Ramstr?m, Olof,Zhang, Qiang,Ge, Jiantao,Dong, Hai
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p. 2481 - 2486
(2016/02/12)
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- Tricyclic benzoxaborole compound, preparation method therefor, and use thereof
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The present invention relates to a novel tricyclic benzoxaborole derivative, a preparation method therefor, and an antibiotic pharmaceutical composition comprising the same as an active ingredient.
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Paragraph 0101; 0102; 0103; 0104
(2016/10/08)
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- Tricyclic Benzoxaborole Compound, Preparation Method and Use Thereof
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The present invention relates to a novel tricyclic benzoxaborole derivative, a preparation method thereof, and use of antibiotics pharmaceutical composition including the same as an active ingredient.
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Paragraph 0081-0083
(2016/07/05)
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- Dimethyltin Dichloride Catalyzed Regioselective Alkylation of cis-1,2-Diols at Room Temperature
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Here, we have developed a mild and general method for the regioselective installation of benzyl, allyl, para-methoxybenzyl and naphthyl groups on cis-1,2-diols. The optimized method operates at room temperature using dimethyltin dichloride as catalyst and
- Saikam, Varma,Dara, Saidulu,Yadav, Mahipal,Singh, Parvinder Pal,Vishwakarma, Ram A.
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p. 11916 - 11925
(2016/01/09)
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- Synthesis of (R)-propane-1,2-diol from lactides by dynamic kinetic resolution
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The dynamic kinetic resolution (DKR) of rac-1-tert-butoxypropan-2-ol with isopropenyl acetate in the presence of Novozyme 435 and a ruthenium catalyst produces enantiomerically pure (R)-1-tert-butoxy-2-acetoxy-propane (>99.5 %ee) in a good yield. The product can be easily transformed into (R)-propane-1,2-diol without loss of stereoselectivity. Together with recently published procedures, the herein described DKR offers the possibility to use any lactide source as starting material for the production of (R)-propane-1,2-diol. The chiral diol may serve as the chiral building block for the synthesis of important enantiopure esters, like propylene carbonate, chiral polymers, etc.
- Shuklov, Ivan A.,Dubrovina, Natalia V.,Schulze, Joachim,Tietz, Wolfgang,B?rner, Armin
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p. 3495 - 3497
(2014/06/10)
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- Formation of higher-order structures of chiral poly(ethynylpyridine)s depending on size, temperature, and saccharide recognition
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Amphiphilic 2,6-pyridylene ethynylene "meta-ethynylpyridine" polymers having chiral oligo(oxyethylene) side chains were developed as hosts for saccharide recognition. The polymers were prepared via a Sonogashira reaction and fractionated by gel permeation
- Abe, Hajime,Okada, Kotaro,Makida, Hiroki,Inouye, Masahiko
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supporting information
p. 6930 - 6936,7
(2012/12/12)
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- Copper-catalyzed cross-coupling of nonactivated secondary alkyl halides and tosylates with secondary alkyl grignard reagents
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Practical catalytic cross-coupling of secondary alkyl electrophiles with secondary alkyl nucleophiles under Cu catalysis has been realized. The use of TMEDA and LiOMe is critical for the success of the reaction. This cross-coupling reaction occurs via an SN2 mechanism with inversion of configuration and therefore provides a general approach for the stereocontrolled formation of C-C bonds between two tertiary carbons from chiral secondary alcohols.
- Yang, Chu-Ting,Zhang, Zhen-Qi,Liang, Jun,Liu, Jing-Hui,Lu, Xiao-Yu,Chen, Huan-Huan,Liu, Lei
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supporting information; experimental part
p. 11124 - 11127
(2012/08/28)
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- Palladium-catalyzed asymmetric quaternary stereocenter formation
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An efficient palladium catalyst is presented for the formation of benzylic quaternary stereocenters by conjugate addition of arylboronic acids to a variety of β,β-disubstituted carbocyclic, heterocyclic, and acyclic enones. The catalyst is readily prepared from PdCl2, PhBOX, and AgSbF 6, and provides products in up to 99 % enantiomeric excess, with good yields. Based on this strategy, (-)-α-cuparenone has been prepared in only two steps. Copyright
- Gottumukkala, Aditya L.,Matcha, Kiran,Lutz, Martin,De Vries, Johannes G.,Minnaard, Adriaan J.
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supporting information; experimental part
p. 6907 - 6914
(2012/07/01)
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- Regioselective, borinic acid-catalyzed monoacylation, sulfonylation and alkylation of diols and carbohydrates: Expansion of substrate scope and mechanistic studies
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Synthetic and mechanistic aspects of the diarylborinic acid-catalyzed regioselective monofunctionalization of 1,2- and 1,3-diols are presented. Diarylborinic acid catalysis is shown to be an efficient and general method for monotosylation of pyranoside derivatives bearing three secondary hydroxyl groups (7 examples, 88% average yield). In addition, the scope of the selective acylation, sulfonylation, and alkylation is extended to 1,2- and 1,3-diols not derived from carbohydrates (28 examples); the efficiency, generality, and operational simplicity of this method are competitive with those of state-of-the-art protocols including the broadly applied organotin-catalyzed or -mediated reactions. Mechanistic details of the organoboron-catalyzed processes are explored using competition experiments, kinetics, and catalyst structure-activity relationships. These experiments are consistent with a mechanism in which a tetracoordinate borinate complex reacts with the electrophilic species in the turnover-limiting step of the catalytic cycle.
- Lee, Doris,Williamson, Caitlin L.,Chan, Lina,Taylor, Mark S.
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supporting information; experimental part
p. 8260 - 8267
(2012/07/14)
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- Folding of a donor-containing ionene by intercalation with an acceptor
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Cationic ionenes that bear electron-rich 1,5-dialkoxynaphthalene (DAN) units within the alkylene segment were allowed to interact with different types of electron-deficient, acceptor-containing molecules in an effort to realize intercalation-induced folding of the ionenes; the collapse of the chains was expected to occur in such a way that the donor and acceptor units become arranged in an alternating fashion. Several acceptor-bearing molecules were prepared by the derivatization of pyromellitic dianhydride and naphthalene tetracarboxylic dianhydride with two different oligoethylene glycol monomethyl ether monoamines. This yielded acceptor molecules with different water solubility and allowed the examination of solvophobic effects in the folding process. UV/Vis spectroscopic studies were carried out by using a 1:1 mixture of the DAN-ionenes and different acceptor molecules in water/DMSO solvent mixtures. The intensity of the charge-transfer (CT) band was seen to increase with the water content in the solvent mixture, thereby suggesting that the intercalation is indeed aided by solvophobic effects. The naphthalene diimide (NDI) bearing acceptor molecules consistently formed significantly stronger CT complexes when compared to the pyromellitic diimide (PDI) bearing acceptor molecules, which is a reflection of the stronger π-stacking tendency of the former. AFM studies of drop-cast films of different ionene-acceptor combinations revealed that compact folded structures are formed most effectively under conditions in which the strongest CT complex is formed. Know when to fold 'em: When coerced to collapse in a polar solvent in the presence of an electron-deficient amphiphilic folding agent, suitably modified ionenes with a symmetrically positioned electron-rich 1,5-dialkoxylnaphthalene (DAN) unit appear to form an accordion-type folded structure wherein the units are arranged in an alternating fashion (see picture). D=Donor; A=Acceptor. Copyright
- De, Swati,Ramakrishnan
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supporting information; experimental part
p. 149 - 156
(2011/10/08)
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- Ruthenium hydroxide complexes in the racemization of secondary alcohols
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Two well-defined 16-electron ruthenium hydroxide complexes were prepared and successfully used in the racemization of aromatic and aliphatic secondary alcohols. The intrinsic basicity of these new complexes permits for the exclusion of KOtBu in the racemization reaction.
- Nun, Pierrick,Fortman, George C.,Slawin, Alexandra M. Z.,Nolan, Steven P.
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scheme or table
p. 6347 - 6350
(2012/01/31)
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- An atom-economic reaction for synthesis of 1-phenoxy-2-propanol over Al2O3/MgO
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Al2O3/MgO materials with various Mg/Al molar ratios were prepared and characterized by XRD, FT-IR, SEM and BET analysis. These materials were used as catalysts for synthesis of 1-phenoxy-2-propanol (1-PhP) from phenol and propylene oxide as compared with some oxides, i.e. MgO, CaO, ZnO and Al2O3, etc. Al2O3/MgO with Al/Mg molar ratio of 1.5% exhibited outstanding catalytic performance with 98.2% conversion and 99.3% selectivity to 1-PhP at 120 °C for 5 h. This catalyst can be easily recovered and reused due to its heterogeneous catalytic nature.
- Zhang, Yongbo,Lu, Bin,Wang, Xiaoguang,Zhao, Jingxiang,Cai, Qinghai
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experimental part
p. 125 - 129
(2012/05/04)
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- A simple, mild, and regioselective method for the benzylation of carbohydrate derivatives promoted by silver carbonate
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A simple, mild, and regioselective method has been developed for the selective benzylation and p-methoxybenzylation of carbohydrate derivatives in high yields using Ag2CO3 as the promoter. Benzylation of base-labile substrates, for w
- Malik, Satish,Dixit, Vaibhav A.,Bharatam, Prasad V.,Kartha, K.P. Ravindranathan
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experimental part
p. 559 - 564
(2010/10/04)
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- N-Heterocyclic carbene-ruthenium complexes for the racemization of chiral Alcohols
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"Chemical Equation Presented" The activity of well-defined, 16-electron ruthenium complexes bearing an N-heterocyclic carbene ligand in the racemization of chiral alcohols is reported. Mechanistic considerations are also presented.
- Bosson, Johann,Nolan, Steven P.
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supporting information; experimental part
p. 2039 - 2043
(2010/06/20)
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- Ferric perchlorate as an efficient and useful catalyst for the selective benzylation and methylation of alcohols with benzyl chloride and methyl iodide
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A mild and efficient method was developed for selective benzylation and methylation of hydroxyl compounds in the presence of a catalytic amount of ferric perchlorate. We showed that ferric perchlorate was very effective in selectively promoting the benzylation and methylation of primary aliphatic and benzylic alcohols versus secondary aliphatic alcohols and phenolic hydroxy groups. Graphical abstract: [Figure not available: see fulltext.]
- Behbahani, Farahnaz K.,Heravi, Majid M.,Oskooie, Hossien A.
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experimental part
p. 181 - 184
(2010/03/26)
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- Identification of absolute helical structures of aromatic multilayered oligo(m-phenylurea)s in solution
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(Chemical Equation Presented) The oligomeric aromatic ureas bearing N,N′-dimethylated urea bonds such as 3 have aromatic multi-layered structure, based on the (cis,cis)-urea structure, and also have dynamic helical structure (all-R or all-S axis chirality) when the benzene rings are connected at the meta positions. The absolute helical structure of oligo(m-phenylurea)s were identified by the empirical and theoretical studies on the CD and vibrational CD (VCD) spectra. Thus, each enantiomer of the oligo(m-phenylurea)s 4 bearing a chiral N-2-(methoxyethoxyethoxy)propyl group were synthesized. Intense dispersion-type CD spectra of 4 were observed, which indicated the induction of handedness in the helical structure. In the VCD spectra of 4 in the film state, the signals due to the carbonyl and aromatic ring vibrations were seen with negative and positive values for compounds 4a and 4b, respectively. The calculations of both CD and VCD spectra of oligo(m-phenylurea)s 3 without any chiral N-substituent gave the same assignment about the axis chirality of 4. Thus, the absolute configurations of 4a and 4b are all-R and all-S structures, respectively. 2009 American Chemical Society.
- Kudo, Mayumi,Hanashima, Takayuki,Muranaka, Atsuya,Sato, Hisako,Uchiyama, Masanobu,Azumaya, Isao,Hirano, Tomoya,Kagechika, Hiroyuki,Tanatani, Aya
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experimental part
p. 8154 - 8163
(2010/02/28)
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- Synthesis of new enantiopure proton-ionizable crown ethers containing a dialkylhydrogenphosphate moiety
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Seven new enantiopure proton-ionizable crown ethers containing a dialkylhydrogenphosphate moiety were prepared starting from optically active dialkyl-substituted oligoethylene glycols and phosphorus oxychloride followed by mild hydrolysis of the resulting macrocyclic chlorophosphates. Pentaethylene glycols having primary hydroxyl groups gave good yields of 17-crown-6 type ethers. Pentaethylene glycols with secondary hydroxyl groups rendered about the same amount of 17-crown-6 ethers and open chain dihydrogenphosphates in low yields. Tetraethylene glycols are reluctant to undergo macrocyclization with phosphorus oxychloride, especially the ones which contain secondary hydroxyl groups.
- Kovacs, Ilona,Huszthy, Peter,Bertha, Ferenc,Sziebert, Denes
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p. 2538 - 2547
(2007/10/03)
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- Amino alcohols as ligands for nickel-catalyzed Suzuki reactions of unactivated alkyl halides, including secondary alkyl chlorides, with arylboronic acids
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Suzuki cross-coupling reactions of an unprecedented array of unactivated primary and secondary alkyl halides (including challenging alkyl chlorides) can be accomplished through the use of nickel/amino alcohol-based catalysts. Both the nickel precatalyst and the amino alcohols (prolinol or trans-2-aminocyclohexanol) are commercially available and air-stable. In view of the remarkable diversity of amino alcohols that are readily accessible, this discovery may open the door to the rapid development of versatile catalysts for a wide range of cross-coupling processes. Copyright
- Gonzalez-Bobes, Francisco,Fu, Gregory C.
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p. 5360 - 5361
(2007/10/03)
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- Solvolysis of benzyl alcohols and ethers in 1,2-diols and application to a deprotection of benzyl ether-type protecting groups
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Some kinds of benzyl alcohols and ethers react with 1,2-diols, such as ethylene glycol and propylene glycol, at 130-190°C to give 2-hydroxyethyl or 2-hydroxypropyl ethers. Application of this reaction to a deprotection of benzyl ether-type protecting groups, under neutral conditions, was also described. Copyright
- Miyake, Hideyoshi,Fujimura, Masahiro,Tsumura, Takatsugu,Sasaki, Mitsuru
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p. 778 - 779
(2007/10/03)
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- Benzylation of alcohols by using bis[acetylacetonato]copper as catalyst
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Selective O-benzylation of primary hydroxy compounds has been achieved in the presence of bis[acetylacetonato]copper with benzyl chloride. We showed that bis[acetylacetonato]copper was very efficient in promoting the benzylation of primary aliphatic alcohols versus secondary aliphatic alcohols and phenolic hydroxy groups selectively.
- Sirkecioglu, Okan,Karliga, Bekir,Talinli, Naciye
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p. 8483 - 8485
(2007/10/03)
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- Phenoxathiin derivatives as inhibitors of monoamine oxidase
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PCT No. PCT/US97/23486 Sec. 371 Date Mar. 11, 1999 Sec. 102(e) Date Mar. 11, 1999 PCT Filed Aug. 19, 1997 PCT Pub. No. WO98/12190 PCT Pub. Date Mar. 26, 1998The present invention provide phenoxathiin compounds useful in the prophylaxis and treatment of mental disorders, such as depression. The present invention also provides a method for treating a mammal having depression, anxiety or other conditions responsive to inhibition of MAO-A. A method of preparing the compounds of the present invention is also provided.
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- Hierarchical growth of chiral self-assembled structures in protic media
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The location of nine chiral penta(ethylene oxide) side chains at the periphery of a C3-symmetrical hydrogen-bonded extended core gives rise to a thermotropic discotic liquid crystalline material that shows lyotropic phases in polar, protic media. The molecular stacks self-assemble in a reversible and hierarchical fashion, and specific and subtle solvent-molecule interactions together with the created hydrophobic microenvironment account for an unprecedented stabilization of a preferred handedness of the helical stacks by cooperative intermolecular interactions. The presence of either chirality or achirality at the supramolecular level in the stacks can be tuned by temperature and solvent as judged from circular dichroism spectroscopy. A hierarchical growth of the self-assembly is revealed using a variety of spectroscopic techniques and differential scanning calorimetry.
- Brunsveld,Zhang,Glasbeek,Vekemans,Meijer
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p. 6175 - 6182
(2007/10/03)
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- Amino acid analogs for tumor imaging
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The invention provides novel amino acid compounds of use in detecting and evaluating brain and body tumors. These compounds combine the advantageous properties of 1-amino-cycloalkyl-1-carboxylic acids, namely, their rapid uptake and prolonged retention in tumors with the properties of halogen substituents, including certain useful halogen isotopes including fluorine-18, iodine-123, iodine-125, iodine-131, bromine-75, bromine-76, bromine-77 and bromine-82. In one aspect, the invention features amino acid compounds that have a high specificity for target sites when administered to a subject in vivo. Preferred amino acid compounds show a target to non-target ratio of at least 5:1, are stable in vivo and substantially localized to target within 1 hour after administration. An especially preferred amino acid compound is ?18 F!-1-amino-3-fluorocyclobutane-1-carboxylic acid (FACBC). In another aspect, the invention features pharmaceutical compositions comprised of an α-amino acid moiety attached to either a four, five, or a six member carbon-chain ring. In addition, the invention features analogs of α-aminoisobutyric acid.
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- Amino acid analogs for tumor imaging
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The invention provides novel amino acid compounds of use in detecting and evaluating brain and body tumors. These compounds combine the advantageous properties of 1-amino-cycloalkyl-1-carboxylic acids, namely, their rapid uptake and prolonged retention in tumors with the properties of halogen substituents, including certain useful halogen isotopes including fluorine-18, iodine-123, iodine-125, iodine-131, bromine-75, bromine-76, bromine-77 and bromine-82. In one aspect, the invention features amino acid compounds that have a high specificity for target sites when administered to a subject in vivo. Preferred amino acid compounds show a target to non-target ratio of at least 5:1, are stable in vivo and substantially localized to target within 1 hour after administration. An especially preferred amino acid compound is ?18 F!-1-amino-3-fluorocyclobutane-1-carboxylic acid (FACBC). In another aspect, the invention features pharmaceutical compositions comprised of an α-amino acid moiety attached to either a four, five, or a six member carbon-chain ring. In addition, the invention features analogs of α-aminoisobutyric acid.
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- A Raney nickel-sodium hypophosphite combination system for reductive desulfurization without racemization of optically active secondary alcohol
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Sulfides and sulfoxides bearing an optically active secondary alcohol were desulfurized with a Raney nickel (W-2)-sodium hypophosphite combination system to give optically active alcohols in high yields without racemization. However, the combination system was not effective with sulfides which comprise an alkylthio group and the corresponding sulfoxides. This system exhibited the reductive desulfurization of benzylthio or phenylthio other in the presence of a benzyl ether.
- Node, Manabu,Nishide, Kiyoharu,Shigeta, Yukihiro,Obata, Kenichi,Shiraki, Hiroaki,Kunishige, Hideaki
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p. 12883 - 12894
(2007/10/03)
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- Preparation of optically active azophenolic crown ethers containing 1-phenylethane-1,2-diol and 2,4-dimethyl-3-oxapentane-1,5-diol as a chiral subunit: Temperature-dependent enantiomer selectivity in the complexation with chiral amines
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With (2S,4S)-2,4-dimethyl-3-oxapentane-1,5-diol and (S)- or (R)-1-phenylethane-1,2-diol as chiral subunits, optically active azophenolic crown ethers (S,S,S,S)-1, (R,S,S,R)-2, (S,S,S,S)-3 and (R,S,S,R)-4 possessing two phenyl and two methyl substituents together with the p-(2,4-dinitrophenylazo)phenol moiety have been prepared in enantiomerically pure forms. Temperature-dependent enantiomer selectivity in the complexation of these crown ethers with chiral amines has been studied by the UV-visible spectroscopic method in chloroform and from the observed association constants, thermodynamic parameters for the complexation have been calculated.
- Ogasahara, Kazuko,Hirose, Keiji,Tobe, Yoshito,Naemura, Koichiro
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p. 3227 - 3236
(2007/10/03)
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- Highly selective Silver(I) oxide mediated monoprotection of symmetrical diols
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Treatment of symmetrical diol with Ag2O and alkyl halide gave the monoprotected derivative in good to excellent yield.
- Bouzide, Abderrahim,Sauve, Gilles
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p. 5945 - 5948
(2007/10/03)
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- The enantiomer ratio strongly depends on the alkyl part of the acyl donor in transesterification with lipase B from Candida antarctica
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Three secondary alcohols, 1-phenoxy-, 1-phenylmethoxy- and 1-(2-phenylethoxy)-2-propanol, have been resolved by transesterification with the acyl donors 2-chloroethyl butanoate, 2,2,2-trichloroethyl butanoate, vinyl butanoate and butanoic anhydride using lipase B from Candida antarctica as catalyst in hexane. The enantiomer rate E, which was calculated on the basis of a ping-pong bi-bi mechanism, was highest when 2-chloroethyl butanoate was used as acyl donor, however the reaction was reversible. It was shown that the E-value increased when the amount of 2,2,2-trichloroethyl butanoate was reduced. It is also indicated that butanoic anhydride and vinyl butanoate make the lipase less specific probably by acylation. Copyright (C) Elsevier Science Ltd.
- Hoff, Bard H.,Anthonsen, Henrik W.,Anthonsen, Thorleif
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p. 3187 - 3192
(2007/10/03)
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- SYNTHESIS OF ENANTIOMERIC N-(2-PHOSPHONOMETHOXYPROPYL)DERIVATIVES OF PURINE AND PYRIMIDINE BASES. II. THE SYNTHON APPROACH
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Another approach to (R)- and (S)-N-(2-phosphonomethoxypropyl) derivatives of purine and pyrimidine bases (PMP derivatives) I and II is described, consisting in alkylation of the heterocyclic base with (R)- and (S)-2-propyl p-toluenesulfonates (X and XVIII) followed by transsilylation of the intermediary N- derivatives XI and XIX.The key intermediates X and XVIII were obtained from 1-benzyloxypropanols VI and XIV by two routes: (i) condensation with bis(2-propyl) p-toluenesulfonyloxymethylphosphonate (XIII), hydrogenolysis of the obtained 1-benzyloxy-2-bis(2-propyl)phosphonylmethoxypropanes VIII and XVI over Pd/C to 2-bis(2-propyl)phosphonylmethoxypropanols IX and XVII and tosylation of the latter or (ii) chloromethylation of compounds VI and XIV and subsequent reaction of the chloromethyl ethers VII and XV with tris(2-propyl) phosphite and further processing of the benzyl ethers VIII and XVI analogous to the enantiomeric propanols IX and XVII.This approach was used for the synthesis of derivatives of adenine (Ia, IIa), 2,6-diaminopurine (Ib, IIb) and 3-deazaadenine (Ic, IIc).Their guanine counterparts Ie and IIe were prepared by hydrolysis of 2-amino-6-chloropurine intermediates XId and XIXd. 6-Chloropurine was converted into diester XIi by reaction with tosylate X, which on reaction with thiourea and subsequent ester cleavage afforded the 6-thiopurine derivative Ij.Analogously, 2-amino-6-chloropurine derivative XId reacted with thiourea to give 9-(R)-(2-phosphonomethoxypropyl)-2-thioguanine (If), or with dimethylamine under formation of (2-phosphonomethoxypropyl)-2-amino-6-dimethylaminopurine (Ig).Hydrogenolysis of compound XId gave 9-(R)-(2-phosphonomethoxypropyl)-2-aminopurine (Ik).Hydrolytic deamination of adenine derivatives Ia and IIa led to enantiomeric (2-phoshonomethoxypropyl)hypoxanthines Ih and IIh.
- Holy, Antonin,Dvorakova, Hana,Masojidkova, Milena
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p. 1390 - 1409
(2007/10/02)
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- Preparation and Enantiomer Recognition of Chiral Azophenolic Crown Ethers Having three Chiral Barriers on each of the Homotopic Faces
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Homochiral azophenolic crown ethers 1 and 2 having three chiral barriers, that is, the phenyl group, the methyl group, and the cyclohexane moiety on each of the homotropic faces have been prepared.The enantiomer recognition toward chiral 2-aminoethanol derivatives has been examined.
- Naemura, Koichiro,Asada, Masaki,Hirose, Keiji,Tobe, Yoshito
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p. 1873 - 1876
(2007/10/03)
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- Stereoselectivity of Baker's yeast reduction of 2-propanones: influence of substituents.
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The stereoselectivity of Baker's yeast reduction of prochiral alpha-oxygenated 2-propanones has been studied by varying the substrate structure. The 1-hydroxy-3-methoxy-3-propanone 1a was reduced to the corresponding alcohol (R)-2a with 88% enantiomeric excess. Replacing the hydroxy group in 1a with phenoxy or benzyloxy (1b and 1c) gave the alcohols (S)-2b and (S)-2c with 53 and 32% ee, respectively. Reduction of the methyl ketone 1d gave the alcohol (S)-2d with 91% ee. Attempts to improve the enantioselectivity of the reduction of 1c by lowering the substrate concentration or addition of selective reductase inhibitors had only small effect on the enantioselectivity.
- Waagen,Partali,Hollingsaeter,Huang,Anthonsen
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p. 506 - 510
(2007/10/02)
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- Acyclic nucleosides: Synthesis of 1-[(1-hydroxy-2-propoxy)methyl]thymine, 6-azathymine, uracil, and 6-azauracil as potential antiviral agents
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A series of acyclic nucleosides have been synthesized. Thymine, 6- azathymine, uracil, and 6-azauracil were silylated with hexamethyldisilazane in the presence of ammonium sulfate and then coupled with 1-benzyloxy-2- chloromethoxypropane to give the corresponding 1-(1-benzyloxy-2- propoxy)methyl derivatives. A minor quantity of benzyloxymethylated product was also obtained in each case. Hydrogenolysis of the protected acyclic nucleosides with palladium(II) hydroxide afforded the title compounds. None of the compounds exhibited significant antiviral activity against human immunodeficiency virus (HIV).
- Wang,Chen,Tzeng
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p. 1201 - 1213
(2007/10/02)
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- A new synthesis of (S)-β-methyl-γ-butyrolactone and (S)-4-benzyloxy-3-methylbutanoic acid
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A stereoselective synthesis of (S)-β-methyl-γ-butyrolactone [(S)-4,5-dihydro-4-methyl-2(3H)-furanone, 1] and of (S)-4-benzyloxy-3-methylbutanoic acid (2) is described. Both compounds are prepared starting from inexpensive L-ethyl lactate with overall yields of 26% and 30%, respectively. The products are valuable chiral building blocks.
- Berens,Scharf
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p. 832 - 834
(2007/10/02)
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- REDUCTION OF ACETALS WITH CpTiCl3-LiAlH4
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The reduction of cyclic acetals and ketals derived from aromatic or aliphatic aldehydes and ketones with CpTiCl3-LiAlH4 system in diethyl ether at 30 deg C affords the corresponding hydroxyethyl ethers and the corresponding alkyl benzene or aliphatic hydrocarbons.
- Shaozu, Wu,Yin, Chen,Yulan, Zhang
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p. 421 - 424
(2007/10/02)
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- A efficient method for the reductive cleavage of aromatic acetals with ZrCl4-LiAlH4
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In our survey of the chemistry of ZrCl4-LiAlH4, we have found that acetals can be reduced to the corresponding ethers.We have explored the reductive condition and studied the reductive cleavage of different-membered cyclic acetals
- Shaozu, Wu,Yulan, Zhang,Tianhui, Ren
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p. 445 - 447
(2007/10/02)
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