- Practical acetalization and transacetalization of carbonyl compounds catalyzed by recyclable PVP-I
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A novel PVP-I catalyzed acetalizations/transacetalizations of carbonyl compounds has been developed processing with a mild and easy handling fashion. Different types of Acyclic and cyclic acetals were prepared from carbonyl compounds or their acetals successfully. Further applications of newly developed catalytic combination were testified. This protocol featured with simplicity of operation, mild reaction condition, short reaction time, recyclable of catalyst and broad substrates scope with excellent yields.
- Cao, Fu-Rong,Lu, Guangying,Ren, Jiangmeng,Wang, Di,Zeng, Bu-Bing
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- A facile and efficient protocol for esterification and acetalization in a PEG1000-D(A)IL/toluene thermoregulated catalyst-media combined systems
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A novel efficient and recyclable temperature-dependent biphasic catalyst and reaction media combined system comprised of PEG-1000 linked dicationic acidic ionic liquid and toluene was developed and applied in esterification of aromatic acids and acetalization of aromatic aldehydes with good to excellent yields. This system is characteristic of temperature-dependent reversible biphasic property, simple and facile recyclability, high catalytic activity and extensive substrate and reaction adaptability.
- Wang, Yinglei,Zhi, Huizhen,Luo, Jun
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- Bis(perfluorooctanesulfonyl)imide supported on fluorous silica gel: Application to protection of carbonyls
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The immobilization of bis(perfluorooctanesulfonyl)imide (HNPf2) on fluorous silica gel (FSG) and its utilization in protection of carbonyls have been investigated. This system is reasonably general and can be applied to converting several carbonyls to the corresponding acetals and ketals in good to excellent yields. There is no need for the use of anhydrous solvents or inert atmosphere. Recycling studies have shown that the FSG-supported HNPf2 catalyst can be readily recovered and reused several times without significant loss of activity.
- Hong, Mei,Xiao, Guomin
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experimental part
p. 121 - 126
(2012/08/28)
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- Cobalt(II) schiff base functionalized mesoporous silica as an efficient and recyclable chemoselective acetalization catalyst
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Cobalt(II) Schiff base functionalized mesoporous silica was synthesized from covalent attachment via the introduction of Co(OAc)2 to salicylaldimine functionalized mesoporous silica. The catalyst proved to be chemoselective one for the acetalization of aldehydes to the corresponding acetals in alcohol. The immobilized catalyst can be easily recovered and reused for at least ten reaction cycles without significant loss of its catalytic activity.
- Rajabi
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scheme or table
p. 695 - 701
(2010/11/16)
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- Single-step conversion of electron-deficient aldehydes into the corresponding esters in aqueous alcohols in the presence of iodine and sodium nitrite
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The direct conversion of aldehydes into their corresponding esters in the presence of iodine and sodium nitrite in aqueous alcohols is reported. In all these reactions, alcohol serves as reactant and also as reaction medium. Almost quantitative yields were obtained with aldehydes containing electron-withdrawing substituents and heterocyclic aldehydes. Georg Thieme Verlag Stuttgart.
- Kiran,Ikeda, Reiko,Sakai, Norio,Konakahara, Takeo
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experimental part
p. 276 - 282
(2010/03/26)
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- Gallium triiodide as a highly efficient and mild catalyst for the diethyl acetalization of carbonyl compounds
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Diethyl acetals were obtained from carbonyl compounds in good to excellent yields under mild reaction conditions in the presence of triethyl orthoformate and a catalytic amount of gallium triiodide in anhydrous ethanol.
- Ding, Jin-Chang,Xu, Rong,Liu, Miao-Chang,Chen, Xi-An,Wu, Hua-Yue
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experimental part
p. 566 - 568
(2009/07/18)
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- Nucleophilic phosphine-catalyzed [3+2] cycloaddition of allenes with N-(thio)phosphoryl imines and acidic methanolysis of adducts N-(thio)phosphoryl 3-pyrrolines: a facile synthesis of free amine 3-pyrrolines
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In this report, the dipolarophile imines with easily removable activating group O,O-diethyl(thio)phosphoryl have been investigated in the nucleophilic phosphine-catalyzed [3+2] cycloaddition reaction of electron-deficient allenes. Under the catalysis of a tertiary phosphine, N-(thio)phosphorylimines readily undergo the [3+2] cycloaddition reaction with ethyl 2,3-butadienoate or ethyl 2,3-pentadienoate, affording the corresponding N-(thio)phosphoryl 3-pyrrolines in moderate to high yields with good diastereoselectivity. Removal of the (thio)phosphoryl group from the adducts has been successfully achieved via the acidic methanolysis of the P-N bond, giving the free amine 3-pyrrolines in fair to good yields without severe aromatization. Thus, a facile synthesis of N-unsubstituted 3-pyrrolines is established from the phosphine-catalyzed [3+2] cycloaddition reaction of allenes with imines.
- Zhang, Bo,He, Zhengrong,Xu, Silong,Wu, Guiping,He, Zhengjie
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p. 9471 - 9479
(2008/12/22)
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- Iron(III) tosylate in the preparation of dimethyl and diethyl acetals from ketones and β-keto enol ethers from cyclic β-diketones
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An efficient method for conversion of ketones to their corresponding dimethyl and diethyl acetals and of cyclic β-diketones into β-keto enol ethers using Fe(OTs)3 as a catalyst is described. Copyright Taylor & Francis Group, LLC.
- Mansilla, Horacio,Afonso, Maria M.
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p. 2607 - 2618
(2008/12/22)
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- Acid-free, organocatalytic acetalization
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The acid-free, organocatalytic acetalization of various aldehydes and ketones with N,N′-bis[3,5-bis(trifluoromethyl)phenyl]thiourea is presented. The neutral, double hydrogen bonding thiourea catalyst can be used at very low loadings of 0.01-1 mol% at room temperature to furnish the respective acetals in 65-99% yield at turnover frequencies around 600 h-1. Acid-labile TBDMS-protected as well as unsaturated aldehydes can be converted efficiently into their acetals utilizing this very mild and highly practical method.
- Kotke, Mike,Schreiner, Peter R.
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p. 434 - 439
(2007/10/03)
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- Bronsted acidic ionic liquids as efficient and recyclable catalysts for protection of carbonyls to acetals and ketals under mild conditions
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A series of acidic ionic liquids have been used as efficient catalysts for the protection of various carbonyl compounds at room temperature. The features of mild conditions, satisfactory isolated yield, simple workup, and the recyclability of the catalyst were present in this process. Copyright Taylor & Francis, Inc.
- Du, Yuying,Tian, Fuli
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p. 2703 - 2708
(2007/10/03)
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- Sulfamic acid as a cost-effective and recyclable catalyst for protection of carbonyls to acetals and ketals under mild conditions
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An efficient H2NSO3H-catalyzed protection of various carbonyl compounds at room temperature was investigated. The features of mild conditions, cost-efficient catalyst, simple workup, and the recyclability of the catalyst were represented in this process.
- Gong, Weizhong,Wang, Bo,Gu, Yanglong,Yan, Liang,Yang, Liming,Suo, Jishuan
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p. 4243 - 4247
(2007/10/03)
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- A highly efficient and chemoselective method for acetalization of carbonyl compounds catalyzed by TiO2/SO42- solid superacid
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Various types of aldehydes and ketones could be converted to their corresponding diethyl acetals with triethylorthoformate in the presence of TiO2/SO42- solid superacid in good to excellent yield under mild reaction conditions.
- Ma, Yan-Ran,Jin, Tong-Shou,Shi, Sheng-Xun,Li, Tong-Shuang
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p. 2103 - 2108
(2007/10/03)
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- Tetrabutylammonium tribromide (TBATB) as an efficient generator of HBr for an efficient chemoselective reagent for acetalization of carbonyl compounds
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Acyclic and cyclic acetals of various carbonyl compounds were obtained in excellent yields under a mild reaction condition in the presence of trialkyl orthoformate and a catalytic amount of tetrabutylammonium tribromide (TBATB) in absolute alcohol. Chemoselective acetalization of an aldehyde in the presence of ketone, unsymmetrical acetal formation, shorter reaction times, mild reaction conditions, the stability of acid-sensitive protecting groups, high efficiencies, facile isolation of the desired products, and the catalytic nature of the reagent make the present methodology a practical alternative.
- Gopinath, Rangam,Haque, Sk. Jiaul,Patel, Bhisma K.
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p. 5842 - 5845
(2007/10/03)
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- 2,4,4,6-Tetrabromo-2,5-cyclohexadienone (TABCO) as a versatile, efficient, and chemoselective catalyst for the acetalization and transacetalization of carbonyl compounds, the preparation of acetonides from epoxides and acylals (1,1-diacetates) from aldehydes
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The efficient and chemoselective preparation of acetals and ketals from carbonyl compounds, transacetalization reactions, the conversion of epoxides to acetonides, and the preparation of acylals from aldehydes in the presence of catalytic amounts of 2,4,4,6-tetrabromo-2,5-cyclohexadienone (TABCO) are described.
- Firouzabadi, Habib,Iranpoor, Nasser,Shaterian, Hamid Reza
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p. 2195 - 2205
(2007/10/03)
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- Process for the synthesis of organomagnesium compounds using catalysts
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A process for the preparation of organomagnesium compounds from organic halides and magnesium metal in the presence of transition metal catalysts using an activity-enhancing main group metal component. The latter is a compound of a metal of Periodic Table groups 1, 2 or 13 in which elements of Periodic Table groups 14-17 or hydrogen are bonded to the metal. Some of these additional components may also be formed in situ.
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- Process for the preparation of Grignard reagents and novel Grignard reagents
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Grignard reagents which contain a protected aldehyde function are obtained in a particularly advantageous manner from a halogenated aldehyde by reaction with a secondary monoamine to give an open-chain aminal, and conversion of the latter into a Grignard
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- Tungsten hexachloride (WCl6), a highly efficient and chemoselective catalyst for acetalization of carbonyl compounds
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Various types of aldehydes and ketones could be converted chemoselectively to their corresponding 1,3-dioxanes or diethyl acetals in the presence of catalytic amounts of tungsten hexachloride (WCl6) in good to excellent yields in CH2Cl2 or under neat conditions, respectively.
- Firouzabadi,Iranpoor,Karimi
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p. 2255 - 2263
(2007/10/03)
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- W-bromosuccinimide (NBS) as a powerful and chemoselective catalyst for acetalization of carbonyl compounds under almost neutral reaction conditions
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Highly efficient and mild acetalization of various types of carbonyl compounds was achieved using NBS under almost neutral reaction conditions. Due to the neutrality of the medium this method is especially useful for the protection of acid sensitive substrates. Thieme Stuttgart.
- Karimi, Babak
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p. 1456 - 1458
(2007/10/03)
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- 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) as a highly efficient and mild catalyst for diethyl acetalization of carbonyl compounds
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Various types of structurally different carbonyl compounds in the presence of ethyl orthoformate (EtO)3CH could be efficiently converted to their diethyl acetals by using a catalytic amount (1-3 mol%) of DDQ under mild reaction conditions.
- Karimi, Babak,Ashtiani, Ashraf Miri
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p. 1199 - 1200
(2007/10/03)
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- Zirconium tetrachloride (ZrCl4) catalyzed highly chemoselective and efficient acetalization of carbonyl compounds
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Zirconium tetrachloride (ZrCl4) is a highly efficient and chemoselective catalyst for the acetalization, and in-situ transacetalization of carbonyl compounds under mild reaction conditions.
- Firouzabadi, Habib,Iranpoor, Nasser,Karimi, Babak
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p. 321 - 323
(2007/10/03)
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- Development and Application of a Continuous Microwave Reactor for Organic Synthesis
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A laboratory-scale continuous microwave reactor (CMR) has been developed and used to conduct organic syntheses routinely, rapidly, and safely in a range of solvents, under pressures up to 1400 kPa and at temperatures up to 200 deg C.Advantages and applications of the CMR are discussed, along with the rationale for the design.Reactions carried out with the CMR included nucleophilic substitution, addition, esterification, transesterification, acetalization, amidation, base- and acid-catalyzed hydrolysis, isomerization, decarboxylation, and elimination.Name reactions included the Michael addition, Hofmann degradation, Williamson ether synthesis, and the Mannich, Finkelstein, Baylis-Hillman, and Knoevenagel reactions.
- Cablewski, Teresa,Faux, Alan F.,Strauss, Christopher R.
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p. 3408 - 3412
(2007/10/02)
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- Selective Acetalization of Aldehydes with Trialkoxystibine using Allyl Bromide
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Trialkoxystibine has been found to be an effective reagent for selective acetalization of aldehydes with the aid of allyl bromide.
- Liao, Yi,Huang, Yao-Zeng,Zhu, Fang-Hua
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p. 493 - 494
(2007/10/02)
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- AN EFFICIENT SbCl3-METAL SYSTEM FOR ALLYLATION, REDUCTION AND ACETALIZATION OF ALDEHYDES
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SbCl3-Fe or SbCl3-Al could induce allylation of aldehydes with allylic halides at room temperature to give high yields of the corresponding homoallylic alcohols with high regio- and chemoselectivity.SbCl3-Al or SbCl3-Zn in DMF-H2O was found to be an efficient reduction system for conversion of aldehydes to alcohols at room temperature in excellent yields.While alcohol was used as solvent instead of DMF-H2O, the acetalization product was obtained in almost quantitative yield.Catalytic amount of SbCl3 was effective for this purpose.This acetalization method could also be applied to ketone.
- Wang, Wei-Bo,Shi, Li-Lan,Huang, Yao-Zeng
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p. 3315 - 3320
(2007/10/02)
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- HYPERVALENT IODINE IN ORGANIC SYNTHESIS. ACETAL FORMATION UNDER BASIC CONDITIONS AND CARBON DEUTERIATION OF THE ALDEHYDO GROUP
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Aldazines upon treatment with phenyliodosyl diacetate in CH3OH or CH3OD and NaOCH3 are converted smoothly into two equivalents of the corresponding aldehyde dimethylacetal with deuterium incorporation at the aldehydic carbon atom in the case of CH3OD.
- Moriarty, Robert M.,Hu, Henry
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p. 1537 - 1540
(2007/10/02)
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