- Preparation of a Yb(III)-Incorporated porous polymer by post-Coordination: Enhancement of gas adsorption and catalytic activity
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We synthesized a Yb(III)-incorporated microporous polymer (Yb-ADA) and studied its gas adsorption property and catalytic activity. The adamantane-based porous polymer (ADA) was obtained from an ethynyl-functionalized adamantane derivative and 2,5-dibromoterephthalic acid through Sonogashira-Hagihara cross-coupling. ADA had two carboxyl groups which were used for Yb(III) coordination under basic conditions. The Brunauer-Emmett-Teller (BET) surface area of ADA was 970 m2 g-1. As Yb(III) ions were incorporated into ADA, the surface area of the polymer (Yb-ADA) was reduced to 885 m2 g-1. However, Yb-ADA exhibited a significantly enhanced CO2 adsorption capacity despite the reduction of surface area. The CO2 uptakes of ADA and Yb-ADA were 1.56 and 2.36 mmol g-1 at 298 K, respectively. The H2 uptake of ADA also increased after coordination with Yb(III) from 1.15 to 1.40 wt % at 77 K. Yb-ADA showed high catalytic activity in the acetalization of 4-bromobenzaldehyde and furfural with trimethyl orthoformate and could be reused after recovery without severe loss of activity.
- Kim, Hyungwoo,Cha, Min Chul,Park, Hyun Woo,Chang, Ji Young
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Read Online
- 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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- α-Chymotrypsin-Induced Acetalization of Aldehydes and Ketones with Alcohols
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This is the first report of a simple and general method for acetalization of aldehydes via an α-chymotrypsin-induced reaction under mild conditions. A broad range of aromatic and heteroaromatic aldehydes have been acetalized under neutral conditions in good yields using a catalytic amount of chymotrypsin.
- Jiang, Guofang,Lan, Jin,Le, Zhanggao,Xie, Zongbo,Yang, Jiangnan,Zhu, Haibo
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p. 2121 - 2126
(2020/07/14)
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- Photochemical synthesis of acetals utilizing Schreiner's thiourea as the catalyst
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Acetalization of aldehydes is an area of great importance in Organic Chemistry for both synthetic and biological puproses. Herein, we report a mild, inexpensive and green photochemical protocol, where Schreiner's thiourea (N,N′-bis[3,5-bis(trifluoromethyl)-phenyl]-thiourea) is utilized as the catalyst and cheap household lamps as the light source. A variety of aromatic and aliphatic aldehydes were converted into acetals in good to high yields (23 examples, 36-96% yield) and an example of the synthesis of a cyclic acetal is provided. The reaction mechanism was also studied.
- Kokotos, Christoforos G.,Nikitas, Nikolaos F.,Spiliopoulou, Nikoleta
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supporting information
p. 3539 - 3545
(2020/06/25)
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- Synthesis, structural determination and catalytic study of a new 2-D chloro-substituted zinc phosphate, (C8N2H20)[ZnCl(PO3(OH))]2
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A novel chloro-substituted zinc-phosphate, (C8N2H20)[ZnCl(PO3(OH))], has been synthesized by a slow evaporation method in the presence of 1,3-cyclohexanebis- (methylamine), which acts as a template. The structure consists of vertex linked ZnO3Cl and PO3(OH) tetrahedral, assembled into corrugated porous layers [ZnCl(PO3(OH))2]∞ with (4.82) topology. The optical properties were also investigated using Diffuse Reflecting Spectroscopy (DRS), showing that the title compound has semiconducting properties. In addition, the catalytic activity of (C8N2H20)[ZnCl(PO3(OH))]2 has been tested in the acetalisation reaction of aldehydes. The title compound displayed a high catalytic activity with practically total conversion in many examples using MeOD as solvent and as the sole source of acetalisation. More importantly, the reaction crudes are very clean and only the preferred products are found in the NMR spectra.
- Rayes, Ali,Herrera, Raquel P,Moncer, Manel,Ara, Irene,Calestani, Gianluca,Ayed, Brahim,Mezzadri, Francesco
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- Preparation method of acetal or ketal compound
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The invention discloses a preparation method of an acetal or ketal compound. The preparation method comprises the following steps: oscillating aldehyde or ketone, alcohol and a catalyst at 60 DEG C, and carrying out post-treatment after the reaction is finished to obtain the acetal compound, wherein the catalyst comprises alpha-chymotrypsin, the aldehyde or ketone has a structure represented by acompound A, R1 and R2 are respectively and independently selected from aryl, H and alkyl, the alcohol has a structure represented by a compound B, and R3 is selected from saturated alkane. The preparation method provided by the invention is catalyzed by alpha-chymotrypsin, is mild in reaction condition, simple in operation process, low in cost and environment-friendly, and has popularization and application values.
- -
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Paragraph 0021-0030; 0100-0105
(2020/04/22)
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- Photo-organocatalytic synthesis of acetals from aldehydes
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A mild and green photo-organocatalytic protocol for the highly efficient acetalization of aldehydes has been developed. Utilizing thioxanthenone as the photocatalyst and inexpensive household lamps as the light source, a variety of aromatic and aliphatic aldehydes have been converted into acyclic and cyclic acetals in high yields. The reaction mechanism was extensively studied.
- Nikitas, Nikolaos F.,Triandafillidi, Ierasia,Kokotos, Christoforos G.
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supporting information
p. 669 - 674
(2019/02/14)
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- Nickel-Catalyzed Chemoselective Acetalization of Aldehydes With Alcohols under Neutral Conditions
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A molecularly defined NiII-complex catalyzing the chemoselective acetalization of aldehydes with alcohols under neutral conditions is reported. The reaction is general, efficient and showed a wide substrate scope (including aliphatic aldehydes) as well as excellent functional group tolerance. Reusability of the present nickel catalyst is also demonstrated.
- Subaramanian, Murugan,Landge, Vinod G.,Mondal, Akash,Gupta, Virendrakumar,Balaraman, Ekambaram
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supporting information
p. 4557 - 4562
(2019/08/30)
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- Chemoselective Nucleophilic Functionalizations of Aromatic Aldehydes and Acetals via Pyridinium Salt Intermediates
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The development of a novel chemoselective functionalization can diversify the strategy for synthesizing the target molecules. The perfect chemoselectivity between aromatic and aliphatic aldehydes is difficult to achieve by the previous methods. The aromatic aldehyde-selective nucleophilic addition in the presence of aliphatic aldehydes was newly accomplished. Namely, the aromatic aldehyde-selective nucleophilic addition using arenes and allyl silanes proceeded in the presence of trialkylsilyl triflate and 2,2′-bipyridyl, while the aliphatic aldehydes completely remained unchanged. The reactive pyridinium-type salt intermediate derived from an aromatic aldehyde chemoselectively underwent the nucleophilic substitution. Moreover, the aromatic acetals as the protected aldehydes could be directly transformed into similar pyridinium salt intermediates, which reacted with various nucleophiles coexisting with the aliphatic aldehydes.
- Kawajiri, Takahiro,Kato, Maho,Nakata, Hiroki,Goto, Ryota,Aibara, Shin-Yo,Ohta, Reiya,Fujioka, Hiromichi,Sajiki, Hironao,Sawama, Yoshinari
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p. 3853 - 3870
(2019/03/07)
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- Formation of Acetals and Ketals from Carbonyl Compounds: A New and Highly Efficient Method Inspired by Cationic Palladium
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The development of a new, highly efficient, and simple method for masking carbonyl groups as acetals and ketals is described. This methodology relies on the nature of the palladium catalyst to direct the acetalization/ketalization reaction. This new protocol is mild and proceed with a very low catalyst loading at ambient temperatures. The method has been extended to a wide variety of different carbonyl compounds with various steric encumbrances to form the corresponding acetals and ketals in excellent yields.
- Green, Shawn D.,Kindoll, Tyler,Lazaro-Martinez, Brenda,Mensah, Enoch A.,West, Jesse
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p. 1810 - 1814
(2019/09/09)
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- Multicomponent Aromatic and Benzylic Mannich Reactions through C?H Bond Activation
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Multicomponent Mannich reactions through C?H bond activation are described. These transformations allowed for the straightforward generation of densely substituted benzylic and homo-benzylic amines in good yields. The reaction involves a reaction between two transient species: an organometallic species, generated by transition-metal-catalyzed sp2 or sp3 C?H bond activation and an in situ generated imine. The use of an acetal as an aldehyde surrogate was found essential for the reaction to proceed. The process could be successfully applied to RhIII-catalyzed sp2 C?H bond functionalization and extended to CuII-catalyzed sp3 C?H bond functionalization.
- Xavier, Tania,Rayapin, Corinne,Le Gall, Erwan,Presset, Marc
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supporting information
p. 13824 - 13828
(2019/11/03)
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- Unique chemoselective Mukaiyama aldol reaction of silyl enol diazoacetate with aldehydes and acetals catalyzed by MgI2 etherate
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Functionalized diazo acetoacetates are prepared by an efficient Mukaiyama aldol reaction between 3-TBSO-2-diazo-3-butenoate with aldehydes and acetals under mild reaction conditions. A variety of substituted aldehydes and the corresponding acetals are both accessible in good to excellent yields through this methodology. MgI2 etherate (MgI2·(OEt2)n) is the preferred catalyst and, the addition proceeds without decomposition of the diazo moiety. In addition, this MgI2·(OEt2)n-catalyzed Mukaiyama aldol reaction shows unique chemoselectivity towards aldehydes and acetals.
- Meng, Xiangwei,Pan, Haokun,Zhong, Tengjiang,Zhang, Xingxian
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- House bulb light-induced photochemical acetalization of carbonyl compounds catalyzed by Eosin Y
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We have systematically studied the reactions of acetalization and found that high reaction efficiency can be achieved using cheap and readily available organic Eosin Y as catalyst. The reaction proceeds smoothly under house bulbs and shows excellent functional group tolerance. The substrates of the reaction system are compatible with aromatic aldehydes, aliphatic aldehydes, aromatic ketones, and cyclic ketones with high yields.
- Zhou, Quan,Jia, Tao,Li, Xiao-Xuan,Zhou, Lin,Li, Chang-Jiang,Feng, Yi-Si
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supporting information
p. 1068 - 1075
(2018/05/23)
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- Ru(II)-functionalized SBA-15 as highly chemoselective, acid free and sustainable heterogeneous catalyst for acetalization of aldehydes and ketones
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Combining electron deficient Ru(II) coordination sites with organofunctionalized SBA-15, (L)Ru(II)@SBA-15, result in a mild, neutral, water scavenger free and chemo-selective acetalization catalyst for cyclic/acyclic acetals. Vacant coordination sites of ruthenium in (L)Ru(II)@SBA-15 activates protecting groups as well as reactants simultaneously and restricts the reverse acetalization reaction. Synthesized (L)Ru(II)@SBA-15 catalyst has been thoroughly characterized and act as competitive catalyst compared to conventional acid catalysts. (L)Ru(II)@SBA-15 performs high catalytic activity as well as selectivity within 20 min with high TOF. The catalyst can be recycled and reaction parameters are optimized.
- Lazar, Anish,Betsy,Vinod,Singh
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- Hydrothermal synthesis of chiral inorganic-organic CoII complex: Structural, thermal and catalytic evaluation
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By heating the cobalt chloride hexahydrate (CoCl2·6H2O) with the R form of the organic amine α-methylbenzylamine (C8H11N) under hydro(solvo)thermal conditions, we have successfully generated the corresponding non-centrosymmetric homochiral hybrid tris (α-methylbenzylammonium tetrachloridocobaltate chloride [R-(C8H12N)3][CoCl4]Cl abbreviated R(MBA)Co. We present the growth conditions together with a characterization of the single crystals by means of X-ray single-crystal diffraction, Fourier-transform infrared, TG/TDA thermal decomposition and catalytic properties. This inorganic–organic hybrid compound crystallizes in the chiral space group P21 and exhibits a supramolecular-layered organization wherein a double layer of (R)-methylbenzylammonium cations and the uncoordinated chloride anions are sandwiched between anionic layers, formed by isolated tetrachloridocobaltate tetrahedra. The crystal packing is governed by a three-dimensional network of N/C–H?Cl hydrogen bonds between the inorganic and organic moieties and C–H···π interactions between the aromatic rings of the organic moieties themselves. Thermal analysis discloses a phase transition at the temperature 130 °C. The Co complex was also employed as suitable catalyst activating the acetal formation reaction of aldehydes using MeOH as solvent and as the unique source of acetalization.
- Salah, Assila Maatar Ben,Herrera, Raquel P.,Na?li, Houcine
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p. 356 - 362
(2018/05/29)
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- Visible-light-induced acetalization of aldehydes with alcohols
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In this work, we have achieved a simple and general method for acetalization of aldehydes by means of a photochemical reaction under low-energy visible light irradiation. A broad range of aromatic, heteroaromatic, and aliphatic aldehydes have been protected under neutral conditions in good to excellent yields using a catalytic amount of Eosin Y as the photocatalyst. Our visible light mediated acetalization strategies are successful for more challenging acid-sensitive aldehydes and sterically hindered aldehydes. Notably, this protocol is chemoselective to aldehydes, while ketones remain intact.
- Yi, Hong,Niu, Linbin,Wang, Shengchun,Liu, Tianyi,Singh, Atul K.,Lei, Aiwen
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supporting information
p. 122 - 125
(2017/11/27)
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- Acid-catalyzed highly diastereoselective and effective synthesis of 1,3-disubstituted tetrahydropyrano[3,4-b]indoles
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We successfully explored for the first time that trifluoroacetic acid (TFA) can effectively catalyze the oxa-Pictet-Spengler reaction of secondary tryptophols and acetals to synthesize 1,3-disubstituted 1,3,4,9-tetrahydropyrano[3,4-b]indoles in high yield (up to >99%) and diastereoselectivity (>20:1). The secondary tryptophols were synthesized from indole-3-acetic acid. The one-pot synthesis of tetrahydropyrano[3,4-b]indoles was successfully developed from secondary tryptophols and in situ prepared acetals from aldehydes and trimethylorthoformate and thus the cost-efficiency of the protocol was effectively enhanced. Finally, the catalytic asymmetric synthesis of the 1,3-disubstituted tetrahydropyrano[3,4-b]indole was also demonstrated after enantioselective achievement of highly enantiopure secondary tryptophols.
- Wang, Pei,Zhao, Jia-Zhen,Li, Hong-Feng,Liang, Xiang-Ming,Zhang, Ya-Lun,Da, Chao-Shan
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supporting information
p. 129 - 133
(2016/12/23)
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- Method for synthesis of acetal derivative by photocatalysis
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The invention discloses a method for synthesis of an acetal derivative by photocatalysis. The method consists of: in the presence of a photocatalyst, dissolving aldehyde and lower alcohol in an organic solvent, mixing the substances evenly, then carrying out reaction for 4-12h in an inert gas atmosphere and under a 300-600nm wavelength illumination condition, and then carrying out separation and purification, thus obtaining the acetal derivative. According to the invention, aldehyde, lower alcohol and the photocatalyst are employed to construct the acetal derivative by one step directly under room temperature illumination, the preparation method is simple, has mild conditions, and can prepare the target product high selectively; the raw materials are cheap and easily available, green and economical, also the method has very good substrate applicability, greatly expands the substrate range, and has very great application potential in biomedical synthetic intermediates.
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Paragraph 0023
(2017/04/19)
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- Crystallisation, thermal analysis and acetal protection activity of new layered Zn(II) hybrid polymorphs
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Two new polymorphic mononuclear complexes, with analogous structural formula (C6H9N2)2[Zn(H2O)6](SO4)2·2H2O, of zinc(ii) templated by 2-amino-6-methylpyridinium ligand have been discovered. These polymorphic hybrid crystals, which differ only in terms of their crystal structures, were prepared in one-step synthesis under ambient conditions and investigated for their thermal and catalytic properties. Single-crystal X-ray diffraction of the obtained materials revealed that polymorphs 1 and 2 crystallise in the triclinic system, space group P1. In an effort to further explore the form diversity of these compounds, the structural arrangements and intermolecular interactions such as hydrogen-bonding and π?π interactions are discussed from which supramolecular assembly was formed. Meanwhile, these new polymorphic forms can be described as the stacking of 3D layers where the interlayer distances are 13.23 and 12.59 ? for 1 and 2, respectively. The thermal behaviour of the precursors checked by TG-DTA analysis for both zinc sulfate polymorphs and variable temperature powder X-ray diffraction (VT-PXRD) show successive intermediate crystalline anhydrous phases upon dehydration in 1. The catalytic activity of both polymorphic structures has been tested in the acetalisation reaction of aldehydes as a benchmark process. Interestingly, both complexes showed excellent activity with almost total conversion in many examples and using MeOH as solvent and as the unique source of acetalisation.
- Sa?d, Salem,Na?li, Houcine,Bataille, Thierry,Herrera, Raquel P.
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p. 5365 - 5374
(2016/07/21)
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- Direct Asymmetric Friedel-Crafts Reaction of Naphthols with Acetals Catalyzed by Chiral Bronsted Acids
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The Friedel-Crafts method synthesis of chiral ethers from various acetals and naphthols catalyzed by chiral Bronsted acids with acetic acid as an effective additive is described. We found that the chiral phosphoric acid (R)-TRIP could efficiently catalyze the asymmetric Friedel-Crafts reaction of naphthols with acetals affording chiral ethers in good enantioselectivity and yield.
- Qin, Long,Wang, Pei,Zhang, Yixin,Ren, Zhengxiang,Zhang, Xin,Da, Chao-Shan
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supporting information
p. 571 - 574
(2016/03/01)
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- Zeolite nanofiber assemblies as acid catalysts with high activity for the acetalization of carbonyl compounds with alcohols
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Zeolite nanofiber assemblies (HNB-MOR) as efficient heterogeneous catalysts for the formation of a range of acetals in good yields. The mesoporosity of HNB-MOR benefits mass transfer, and the strong acidic sites on HNB-MOR facilitate acetalization activity. The catalyst can be reused 10 times without loss of activity.
- Liu, Taotao,Fu, Wenqian,Zheng, Xiang,Jiang, Jun,Hu, Maolin,Tang, Tiandi
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p. 18217 - 18221
(2014/05/20)
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- COMPOUNDS AND THEIR USE TO TREAT HISTAMINE H3 RELATED DISORDERS
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The present invention provides compounds of formula (1) and pharmaceutically acceptable salts thereof, wherein R1, R2, R3, R4, R5, R6, R7, R8, R9, R10, R11, R12, R13, R14, R15, R16, R17, R18, R19, R20, m, n, p, q, Q1, Q2, Q3, Q4, Q5, Q6, X1, X2, X3, X4, A1 and L1, are as defined in the specification, processes for their preparation, pharmaceutical compositions containing them and their use in therapy.
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Page/Page column 177
(2013/03/26)
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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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- Indium(III) triflate catalysed transacetalisation reactions of diols and triols under solvent-free conditions
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Acyclic acetals and ketals undergo transacetalisation in the presence of catalytic quantities of indium(III) triflate (In(OTf)3) and diols or triols under solvent-free conditions to generate the corresponding cyclic acetals and ketals in excellent yield. The methodology has been further developed to encompass a tandem acetalisation-acetal exchange protocol, which provides a facile and high yielding route to cyclic ketals from unreactive ketones under very mild reaction conditions.
- Smith, Brendan M.,Kubczyk, Tomasz M.,Graham, Andrew E.
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supporting information; experimental part
p. 7775 - 7781
(2012/09/21)
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- Catalytic synthesis of γ-alkoxy-α-keto esters
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Copper(II) triflate effectively catalyzes the reaction of (trimethylsilyloxy)acrylic esters and acetals to form -alkoxy - keto esters. The reaction proceeds under mild conditions providing products in good to excellent yields. The substrate scope was investigated, and it was demonstrated that the products could be converted into related compounds such as γ-hydroxy -α- keto esters and α-oximes. Georg Thieme Verlag Stuttgart - New York.
- Krebs, Anke,Bolm, Carsten
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supporting information; experimental part
p. 671 - 673
(2011/05/16)
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- Mesoporous aluminosilicate-catalyzed allylation of carbonyl compounds and acetals
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A mesoporous aluminosilicate (Al-MCM-41) was found to be an effective heterogeneous catalyst for the reaction of both carbonyl compounds and acetals with allylsilanes to afford the corresponding homoallyl silyl ethers and homoallyl alkyl ethers, respectively. Both the mesoporous structure and the presence of aluminum moiety were indispensable for the high catalytic activity of Al-MCM-41. Moreover, Al-MCM-41 could catalyze the reaction of acetals chemoselectively in the presence of the corresponding carbonyl compounds. The solid acid catalyst Al-MCM-41 could be recovered easily by filtration and could be reused three times without a significant loss of catalytic activity.
- Ito, Suguru,Hayashi, Akira,Komai, Hirotomo,Yamaguchi, Hitoshi,Kubota, Yoshihiro,Asami, Masatoshi
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supporting information; experimental part
p. 2081 - 2089
(2011/04/19)
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- Metal organic frameworks as solid acid catalysts for acetalization of aldehydes with methanol
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Room temperature acetalization of aldehydes with methanol has been carried out using metal organic frameworks (MOFs) as solid heterogeneous catalysts. Of the MOFs tested, a copper-containing MOF [Cu3(BTC)2] (BTC=1,3,5-benzenetricarboxylate) showed better catalytic activity than an iron-containing MOF [Fe(BTC)] and an aluminium containing MOF [Al 2(BDC)3] (BDC=1,4-benzenedicarboxylate). The protocol was validated for a series of aromatic and aliphatic aldehydes and used to protect various aldehydes into commercially important acetals in good yields without the need of water removal. In addition, the reusability and heterogeneity of this catalytic system was demonstrated. The structural stability of MOF was further studied by characterization with powder X-ray diffraction, Brunauer-Emmett- Teller surface area measurements and Fourier-transformed infrared spectroscopic analysis of a deactivated catalyst used to convert a large amount of benzaldehyde. The performance of copper MOF as acetalization catalyst compares favourably with those of other conventional homogeneous and heterogeneous catalysts such as zinc chloride, zeolite and clay. Copyright
- Dhakshinamoorthy, Amarajothi,Alvaro, Mercedes,Garcia, Hermenegildo
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scheme or table
p. 3022 - 3030
(2011/02/24)
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- Reductive openings of benzylidene acetals revisited: A mechanistic scheme for regio- and stereoselectivity
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Despite the importance of regioselective reductive openings of cyclic acetals, mechanistic details are scarce. In this study 4,6-O-benzylidene acetals were used as model compounds for deciphering the mechanism of regioselective openings using a variety of
- Johnsson, Richard,Ohlin, Markus,Ellervik, Ulf
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supporting information; scheme or table
p. 8003 - 8011
(2011/03/18)
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- Carbon tetrabromide/sodium triphenylphosphine-m-sulfonate (TPPMS) as an efficient and easily recoverable catalyst for acetalization and tetrahydropyranylation reactions
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A solid complex, conveniently prepared from carbon tetrabromide and sodium triphenylphos-phine-m-sulfonate (TPPMS), can be used as an easily recoverable catalyst for the selective acetalization of aldehydes and tetrahydropyranylation of alcohols. The catalyst can be recovered by simple pre-cipitation with ether and can be reused at least 7 times without loss of catalytic activity.
- Huo, Congde,Chan, Tak Hang
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experimental part
p. 1933 - 1938
(2011/02/28)
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- Method for preparing 4-[17beta-methoxy-17alpha-methoxymethyl-3-oxestra-4,9-dien-11beta-yl]benzaldehyde (E)-oxime (asoprisnil)
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The present invention relates to a method for the reliable and reproducible preparation of 4-[17β-methoxy-17α-methoxymethyl-3-oxoestra-4,9-dien-11β-yl]benzaldehyde (E)-oxime (asoprisnil) on the pilot and manufacturing scale. Asoprisnil, which is prepared by this method, is distinguished by a very good physical stability and is therefore particularly suitable for the manufacture of solid pharmaceutical forms (tablets, coated tablets, etc.).
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Page/Page column 7
(2009/04/24)
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- A facile procedure for acetalization of aldehydes and ketones catalyzed by cerium(III) trifluoromethanesulfonate
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Aldehydes and ketones are readily protected in the presence of trialkyl orthoformate and a catalytic amount of cerium(III) trifluoromethanesulfonate under mild conditions to give the corresponding acetals in good to excellent yields. Due to the mild reaction conditions, this method is compatible with acid-sensitive substrates. Copyright
- Ono, Fumiaki,Inatomi, Yoshiko,Tada, Yuusuke,Mori, Masaki,Sato, Tsuneo
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experimental part
p. 96 - 97
(2009/11/30)
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- An efficient and practical synthesis of the HIV protease inhibitor atazanavir via a highly diastereoselective reduction approach
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An efficient and practical synthesis of the HIV-1 protease inhibitor Atazanavir was developed by employing the diastereoselective reduction of ketomethylene aza-dipeptide isostere 10 as the key and final step. The high diastereoselectivity of the amino ketone reduction by lithium tri-iert-butoxyaluminum hydride in diethyl ether to afford the desired svn-1,2-amino alcohol structure was achieved by Felkin- Anh control as a result of the bulky and chiral N-(methoxycarbonyl)-L-tert-leucinyl moiety as the nitrogen protecting group. The coupling of the two key intermediates, N-(methoxycarbonyl)-L-tert-leucine acylated benzyl hydrazine 7 and chloromethyl ketone 9, via an SN2 reaction furnished the amino ketone 10 in high yield under our optimized conditions. Our new methodology features the late introduction of the S-hydroxyl group and the early acylation of benzyl hydrazine and chloromethyl ketone with N-(methoxycarbonyl)-L-tert-leucine, respectively, which confers high efficiency and easy purification.
- Fan, Xing,Song, Yan-Li,Long, Ya-Qiu
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supporting information
p. 69 - 75
(2012/12/31)
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- Reductive openings of acetals: Explanation of regioselectivity in borane reductions by mechanistic studies
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(Graph Presented) The mechanisms of regioselective reductive openings of acetals were investigated in several model systems by a combination of Hammett plots, kinetic experiments, density functional calculations, and 11B NMR. The regioselectivity of borane reductions of cyclic acetals can be controlled by the choice of borane. Lewis acid activation of BH3·NMe 3 increases the reaction rate and renders the borane the most electrophilic species, which associates to the more electron-rich oxygen of the acetal. In contrary, without activation, the regioselectivity is instead directed by the Lewis acid, as exemplified by the reaction with BH 3·THF.
- Johnsson, Richard,Olsson, Dan,Ellervik, Ulf
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p. 5226 - 5232
(2008/12/21)
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- The use of electroosmotic flow as a pumping mechanism for semi-preparative scale continuous flow synthesis
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By employing a series of reactions we demonstrate the use of electroosmotic flow as a continuous pumping mechanism suitable for semi-preparative scale synthesis, affording an array of small organic compounds, of analytical purity, with yields ranging from 0.57-1.71 g h-1. The Royal Society of Chemistry.
- Wiles, Charlotte,Watts, Paul,Haswell, Stephen J.
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p. 966 - 968
(2007/12/31)
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- Acid-catalysed synthesis and deprotection of dimethyl acetals in a miniaturised electroosmotic flow reactor
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Through incorporating a series of polymer-supported acid catalysts into a miniaturised EOF-based flow reactor, we demonstrate a clean and efficient technique for the protection of aldehydes as their respective dimethyl acetal. In addition, we also report the acid catalysed deacetalisation of 11 dimethyl acetals to their respective aldehyde. In all cases, the compounds described are obtained in high yield (>95%) and excellent purity (>99%) without the need for further product purification.
- Wiles, Charlotte,Watts, Paul,Haswell, Stephen J.
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p. 5209 - 5217
(2007/10/03)
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- Cobalt(II)-catalyzed chemoselective synthesis of acetals from aldehydes
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The acetalization of aldehydes has been studied with methanol, ethanol, and 2-propanol using CoCl2 in high yields under reflux conditions. The reaction is simple, efficient, chemoselective and does not involve any other additive.
- Velusamy, Subbarayan,Punniyamurthy
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p. 4917 - 4920
(2007/10/03)
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- An efficient protection of carbonyls and deprotection of acetals using decaborane
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Carbonyls were efficiently converted to the corresponding dimethyl acetals at room temperature using trimethyl orthoformate and 1 mol% of decaborane under a nitrogen atmosphere. In turn, acetals were deprotected to the corresponding carbonyls using 1 mol% of decaborane in aqueous THF chemoselectively.
- Lee, Seung Hwan,Lee, Ji Hee,Yoon, Cheol Min
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p. 2699 - 2703
(2015/10/07)
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- Efficient acetalisation of aldehydes catalyzed by titanium tetrachloride in a basic medium
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The acetalisation of aliphatic and aromatic aldehydes is achieved in a basic medium by using catalytic amount of Ti(IV) chloride in MeOH in the presence of NH3 or Et3N. The present protocol shows many advantages over the well known base or acid catalysis: in fact, in contrast to base-promoted acetalisation, aldehydes with electron-rich carbonyl groups react easily, enolizable aldehydes do not undergo aldol condensation and, in contrast to acid-catalysis, migration of the double bond does not occur in the preparation of α,β-unsaturated acetals.
- Clerici, Angelo,Pastori, Nadia,Porta, Ombretta
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p. 15679 - 15690
(2007/10/03)
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- ANTIVIRALLY ACTIVE HETEROCYCLIC AZAHEXANE DERIVATIVES
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There are described compounds of formula I*, STR1 wherein R. sub.1 is lower alkoxycarbonyl,R 2 is secondary or tertiary lower alkyl or lower alkylthio-lower alkyl, R. sub.3 is phenyl that is unsubstituted or substituted by one or more lower alkoxy radicals, or C 4-C 8 cycloalkyl,R. sub.4 is phenyl or cyclohexyl each substituted in the 4-position by unsaturated heterocyclyl that is bonded by way of a ring carbon atom, has from 5 to 8 ring atoms, contains from 1 to 4 hetero atoms selected from nitrogen, oxygen, sulfur, sulfinyl (--SO--) and sulfonyl (--SO 2--) and is unsubstituted or substituted by lower alkyl or by phenyl-lower alkyl,R 5, independently of R 2, has one of the meanings mentioned for R 2, andR 6, independently of R. sub.1, is lower alkoxycarbonyl,or salts thereof, provided that at least one salt-forming group is present. The compounds are inhibitors of retroviral aspartate protease and can be used, for example, in the treatment of AIDS. They exhibit outstanding pharmacodynamic properties.
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- 11-BENZALDOXIME-ESTRA-DIENE DERIVATIVES, METHODS FOR THEIR PRODUCTION AND PHARMACEUTICALS CONTAINING THESE COMPOUNDS
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This invention relates to new 11-benzaldoxime-estra-diene derivatives of the general formula I STR1 and their pharmaceutically acceptable salts, a method for their production, and pharmaceuticals containing such compounds.The compounds described sho
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- Preparation, Characterization, and Synthetic Uses of Lanthanide(III) Catalysts Supported on Ion Exchange Resins
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Lanthanide(III) catalysts supported on ion exchange resins (Ln-resins) were prepared from Dowex, Amberlite, Amberlyst, and other cation exchange resins. The amount of lanthanides on resin supports was measured through EDTA titration. The results indicated that the lanthanides in aqueous solution exchanged with almost all the cations (H+ or Na+) on the resins to form stable ionic complexes between the lanthanides(III) and the resins. The effects of resin types, resin sizes, and lanthanide salts were investigated with a reaction of indole and hexanal in aqueous solution and with an aldol reaction of benzaldehyde and silyl enol ether in organic solvents. The study found that among ion exchange resins tested Amberlyst XN-1010 and Amberlyst 15 complexed with lanthanides(III) were the most effective catalysts. In addition, the selective Ln-resins were utilized to catalyze acetalization of aldehydes, aldol reaction of formaldehyde or benzaldehyde in aqueous solution, nucleophilic addition to an imine, allylation of an aldehyde, an aza Diels-Alder (DA) reaction, and a ring-opening reaction of an epoxide. Furthermore, glycosylation of alcohol using glucosyl fluoride as a donor was also promoted with the Ln-resin. Thus, this work demonstrated potential uses of lanthanide(III) catalysts supported on ion exchange resins in routine organic reactions.
- Yu, Libing,Chen, Depu,Li, Jun,Wang, Peng George
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p. 3575 - 3581
(2007/10/03)
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- Carbophilic reactions of amines or methanol with thioaldehyde-S-oxides
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Correspondence and reprints Reaction of primary aliphatic amines with 7-ethylenic thioaldehyde-S-oxides la,b affords the corresponding imines 2a,b via a carbophilic addition of amine. When treated with sodium methoxide (1 equiv) and an excess of a primary amine, some methyl sulfinates 3 or 6, bearing a benzylic or allylic chain on the sulfur, are converted into imines 4 or 7. Treatment of the methyl sulfinates 3 with methoxide anion in THF or methanol generally affords a mixture of aldehydes 9, the corresponding dimethylacetals 14, a,a'-dimethoxydisulfides 10, esters 11, thionoesters 12 and methyl a-methoxysulfinates 15, whose ratios depend on the conditions. The formation of these compounds is best explained by a deprotonationelimination of the methyl sulfinates into the corresponding thioaldehyde-S-oxides; which then undergo a carbophilic addition of methoxide anion or methanol. Several possible reaction paths from the so-formed a-methoxysulfenate anions IX are discussed for their conversion into the final compounds. unsaturated sulfinic ester / elimination / thioaldehyde-S-oxide / imine / aldehyde / a,a -dimethoxydisulflde / thionoester / methyl u-methoxysulflnate Eisevier,.
- Baudin, Jean-Bernard,Commenil, Marie-Gabrielle,Julia, Sylvestre A.,Lome, Robert,Ruel, Odile
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p. 1127 - 1141
(2007/10/03)
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- Ce(3+)-Exchanged Montmorillonite (Ce(3+)-Mont) as a Useful Substrate-Selective Acetalization Catalyst
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The acetalization of carbonyl compounds with methanol was investigated in the presence of a cation-exchanged montmorillonite (M(n+)-mont; M(n+) = Ce(3+), Zr(4+), Fe(3+), Al(3+), Zn(2+), H(+) and Na(1+).Ce(3+)-mont was found to be the most effective catalyst for substrate-selective acetalization.Cyclohexanones, benzaldehydes, and acid-sensitive 2-furancarboxaldehyde were converted nearly quantitatively to the corresponding acetals in methanol at 25 deg C in the presence of Ce(3+)-mont.The substrates were activated by a Lewis acidic Ce(3+) cation in the interlayer space on the order of 1 kJ mol-1 as measured by FT-IR.The turnover number was estimated to be up to 2.6E3 based on the number of active acid sites in Ce(3+)-mont.
- Tateiwa, Jun-ichi,Horiuchi, Hiroki,Uemura, Sakae
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p. 4039 - 4043
(2007/10/02)
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- Processes for preparing 1-butyl-2-[2'-(2H-tetrazol-5-yl) biphenyl-4-ylmethyl]-1H-indole-3-carboxylic acid
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The present invention relates to processes for preparing 1-butyl-2-[2''-(2H-tetrazol-5-yl)biphenyl-4-ylmethyl]-1H-indole-3-carboxylic acid and to intermediates useful in such processes. The present invention also relates to a process for deprotecting compounds containing a protected 2H-tetrazolyl group, which process comprises reacting a the protected compound with a Lewis acid in the presence of a thiol.
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- Process for preparing1-butyl-2-[2'-(2H-tetrazol-5-yl)biphenyl-4-ylmethyl1-1H-indole-3-carboxylic acid
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The present invention relates to a process for preparing 1-butyl-2-[2''-(2H-tetrazol-5-yl)biphenyl-4-ylmethyl]-1H-indole-3-carboxylic acid and to intermediates useful in such process.
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- N-(3-pyridylalkyl)sulfonamide compounds which have useful pharmaceutical activity
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Illustrative examples of the N-(3-pyridylalkyl)sulfonamide derivative are represented by the following formulae [II] and [III]: STR1 The derivatives are available for a thromboxane A2 production inhibitor, a thromboxane A2 antagonist, a prostaglandin H2 antagonist, an anti-thrombus agent, a thrombus-preventing agent and an anti-allergy agent.
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- Variable Electronic Properties of the CSNMe2 Group
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The ?I value for the CSNMe2 group has been determined and the value of 0.23 indicates that this group is inductively electron withdrawing.The effect of the p-CSNMe2 group on the solvolysis rate of cumyl chloride has also been determined and, relative to the p-H analogue, this group has a negligible effect on rate. p-CSNMe2 substitution slows the hydrolysis rate of substituted benzaldehyde dimethyl acetals. p-CSNMe2 substitution enhances the solvolysis rate of ArCH(OMs)PO(OEt)2.These variable rate effects on reactions involving cationic intermediates have been interpreted in terms of variable electronic properties of the CSNMe2 group.This group can be cation stabilizing, electroneutral, or cation destabilizing, depending on the charge demands of specific cations.This is a result of a conjugative interaction of CSNMe2 with a cationic center and resultant delocalization of positive charge onto sulfur.The importance of such conjugation is a function of the amount of transition-state charge developed on the carbon bearing the CSNMe2 group.The electronic effects of the amphielectronic p-CSNMe2 group are compared to the more conventional effects of CONMe2 and the m-CSNMe2 analogues.
- Creary, Xavier,Aldridge, Timothy
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p. 4280 - 4285
(2007/10/02)
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- INDIRECT ELECTROCHEMICAL SIDE-CHAIN OXIDATION OF ALKYL AROMATIC COMPOUNDS - SELECTIVE SYNTHESIS OF METHYL BENZOATES OR ORTHOBENZOIC ACID TRIMETHYLESTERS
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The technically important side-chain oxidation of alkyl aromatic compounds to form either methyl benzoates or orthobenzoic acid trimethylesters can be performed electrochemically at low potentials in methanol solution using an undivided cell and tris(2,4-dibromophenyl)amine as redox catalyst.Under neutral or slightly acidic conditions methyl benzoates are selectively formed while under basic conditions the orthoesters are predominating.In a similar way ortho benzoic acid trimethylesters are formed selectively starting from benzaldehyde dimethylacetals.The redox catalyst is stable under the reaction conditions so that several thousand cycles can be performed without noticeable loss.
- Brinkhaus, Karl-Heinz Grosse,Steckhan, Eberhard,Degner, Dieter
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p. 553 - 560
(2007/10/02)
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