- Conjugate addition of acetal-derived benzyl radicals generated from low-valent titanium-mediated CO bond cleavage
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A new method for the generation of benzyl radicals from acetals via low-valent titanium-mediated homolytic CO bond cleavage is presented. The low cost and availability of the developed titanium reagent enable efficient access to α-alkoxy carbon radical species via the developed reaction.
- Suga, Takuya,Nakamura, Masaharu,Takada, Ryusei,Ukaji, Yutaka
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supporting information
p. 1258 - 1260
(2021/05/17)
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- Antimony(v) catalyzed acetalisation of aldehydes: An efficient, solvent-free, and recyclable process
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A highly selective, solvent-free process for the acetalisation of aldehydes was achieved by the use of a readily accessible antimony(v) catalyst which we previously prepared in our lab as a tetraarylstibonium triflate salt ([1][OTf]). High yields of the acetals were achieved in the presence of stoichimetric amounts of either triethoxymethane or triethoxysilane. It was found that triethoxymethane reactions required longer time to reach completion when compared to triethoxysilane reactions which were completed upon mixing of the reagents. The products can be easily separated from the catalyst by distillation which enabled further use of [1][OTf] in additional calytic reactions (up to 6 cycles). Moreover, [1]+ also catalyzed the deprotection of the acetals into their corresponding aldehydes using only water as a solvent.
- Ugarte, Renzo Arias,Hudnall, Todd W.
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p. 1990 - 1998
(2017/06/09)
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- Tropylium salts as efficient organic Lewis acid catalysts for acetalization and transacetalization reactions in batch and flow
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Acetalization reactions play significant roles in the synthetically important masking chemistry of carbonyl compounds. Herein we demonstrate for the first time that tropylium salts can act as organic Lewis acid catalysts to facilitate acetalization and transacetalization reactions of a wide range of aldehyde substrates. This metal-free method works efficiently in both batch and flow conditions, prompting further future applications of tropylium organocatalysts in green synthesis.
- Lyons,Crocker,Enders,Nguyen
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supporting information
p. 3993 - 3996
(2017/09/08)
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- Facile synthesis of Cu3(BTC)2/cellulose acetate mixed matrix membranes and their catalytic applications in continuous flow process
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Metal-organic framework (MOF)-based mixed matrix membranes (MMMs) were fabricated by a combination of Cu3(BTC)2 MOF and polymer cellulose acetate. The cellulose acetate in the MMMs served as the matrix and the Cu3(BTC)2 MOF as the filler. The as-synthesized MMMs were utilized as a heterogeneous catalyst for aldehyde acetalization. The characterization techniques indicated that the Cu3(BTC)2 crystals were uniformly dispersed in the MMMs. The BET surface area of the Cu3(BTC)2-based MMM was measured to be 459 m2 g-1 at 60 wt% Cu3(BTC)2 loading. Furthermore, the MMMs served as an excellent catalyst under our continuous flow catalytic reaction conditions. The optimal catalytic result of benzaldehyde yield reached 94% with 60 wt% Cu3(BTC)2 loading of the MMMs at room temperature and the benzaldehyde diethyl acetal reached 0.59 mmol min-1 gCu-BTC-1.
- Hou, Junying,Luan, Yi,Huang, Xiubing,Gao, Hongyi,Yang, Mu,Lu, Yunfeng
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p. 9123 - 9129
(2017/08/29)
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- Development of a novel Br?nsted acid UiO-66 metal-organic framework catalyst by postsynthetic modification and its application in catalysis
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A novel Br?nsted acid derived metal-organic framework (MOF) has been developed to serve as an efficient heterogeneous catalyst for the acetalization and Morita-Baylis-Hillman reaction. Aromatic sulfonic acid groups were successfully incorporated to the framework of UiO-66 by post-synthetic modifications using commercially available anhydridic reagents. The UiO-66-RArSO3H Br?nsted acid catalyst was fully characterized using SEM, PXRD, FTIR, TGA and N2 adsorption/desorption isotherms. Furthermore, efficient acetalization and Morita-Baylis-Hillman reactions were evaluated to demonstrate the high catalytic performance of the UiO-66-RArSO3H catalyst. The UiO-66-RArSO3H catalyst is compatible with a variety of substituted substrates and can be recycled five times without a compromise in the yield or selectivity.
- Miao, Zongcheng,Qi, Chao,Wensley, Allison M.,Luan, Yi
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p. 67226 - 67231
(2016/07/30)
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- Development of a SO3H-functionalized UIO-66 metal-organic framework by postsynthetic modification and studies of its catalytic activities
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A novel metal-organic framework UiO-66-NH2-derived Br?nsted acid catalyst was synthesized on a gram scale by employing a postsynthetic modification strategy under mild conditions. The nanomorphology of the catalyst was designed and developed to enhance its catalytic performance. Acetalization and benzimidazole formation were evaluated to demonstrate the high reactivity and selectivity of the nanoscaled UiO-66-NH-RSO3H catalyst, which were found to be comparable to the reactivity and selectivity of the strong homogeneous Br?nsted acid catalyst. Furthermore, the UiO-66-NH-RSO3H catalyst was recycled several times without compromising the yield and selectivity. A novel metal-organic framework UiO-66-NH2-derived Br?nsted acid catalyst is synthesized by employing a postsynthetic modification strategy under mild conditions. Acetalization and benzimidazole formation are evaluated to demonstrate the high reactivity and selectivity of the nanoscaled UiO-66-NH-RSO3H catalyst.
- Luan, Yi,Zheng, Nannan,Qi, Yue,Yu, Jie,Wang, Ge
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p. 4268 - 4272
(2015/03/30)
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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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- 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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- Sequential and tandem oxidation/acetalization procedures for the direct generation of acetals from alcohols
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Alcohols are transformed directly into either acyclic or cyclic acetals in both tandem and sequential oxidation/acetalization processes using manganese dioxide, trialkyl orthoformates and catalytic quantities of indium triflate.
- Smith, Brendan M.,Graham, Andrew E.
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p. 4891 - 4894
(2008/02/08)
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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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- Ruthenium(III) chloride-catalyzed chemoselective synthesis of acetals from aldehydes
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A mild and chemoselective acetalization procedure for the protection of various aldehydes in the presence of ketones is described.
- De, Surya K.,Gibbs, Richard A.
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p. 8141 - 8144
(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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- 2,3-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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- The thermally induced synthesis of N-(diethoxyphosphoryl)aldimines
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The reaction of diethyl phosphoroamidate (2) with aromatic aldehyde diethyl acetals (1) carried out at 120-160°C provides a simple, one-step preparation of N-(diethoxyphosphoryl)aldimines (3a-b). The extension of this reaction to aliphatic aldehyde diethyl acetals failed to give the expected imines.
- Zwierzak, Andrzej,Napieraj, Anna
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p. 8789 - 8794
(2007/10/03)
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- ELECTROCHEMICAL CLEAVAGE OF THE DOUBLE BOND OF 1-ALKENYLARENES
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A study has been made of the electrochemical cleavage of the double bond of propenylbenzene (Ia) and p-propenylanisole (Ib), which takes place upon anodic oxidation of (Ia, b) in alcoholic solutions of sodium trifluoroacetate and other electrolytes and which leads to conversion of (Ia, b) to benzaldehyde dialkylacetals.Conditions are found that provide for highly selective (>80percent) conversion of (Ib) and p-propenyltoluene to p-methyl- and p-methoxybenzaldehyde dimethylacetals.
- Ogibin, Yu. N.,Sokolov, A. B.,Ilovaiskii, A. I.,Elison, M. N.,Nikishin, G. I.
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p. 561 - 566
(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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- Photolysis of Alkoxyacetic Acids in the presence of Mercury(II) Oxide and Iodine
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Homolytic decarboxylation of a series of alkoxyacetic acids has furnished alkoxyalkyl alkoxyacetates when no substituents were present at the 2-position.Electron donating and withdrawing 2-substituents, with the exception of trichloromethyl, afforded products due to fragmentation of the alkoxyacetic acids.The reaction pathway is rationalised on the basis of the reactivity of the alkoxyalkyl iodide intermediates.
- Glover, Stephen A.,Golding, Stephen L.,Goosen, Andre,McCleland, Cedric W.
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p. 2479 - 2483
(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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- Reactions of Co-ordinated Ligands. Part 8. Reaction of Grignard Reagents with 2-Alkoxy-1,3-dioxolans; an Improved Route to Aldehydes
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The yields of 2-phenyl-1,3-dioxolan obtained from phenylmagnesium bromide and 2-alkoxy-1,3-dioxolans in which the type Men-O increase as the value of n proceeds along the series 4,3,1,2.Several Grignard reagents(including phenylmagnesium bromide) react with the 2-alkoxy-1,3-dioxolan in which n=2 to give the expected 2-substituted-1,3-dioxolans, whose yields are considerably higher than those of the diethyl acetals obtained from the corresponding reation with ethyl ortoformate.
- Houghton, Roy P.,Morgan, Alan D.
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p. 756 - 758
(2007/10/02)
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