- Acid catalyzed rearrangement of vinyl and ketene acetals
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Substituted vinyl and ketene acetals undergo smooth oxygen-to-carbon rearrangement with a catalytic amount of TMSOTf to afford chain-extended ketones or esters, respectively. The developed procedure has been applied to the stereoselective synthesis of C-glycosides from the corresponding anomeric vinyl ethers.
- Maziarz, Elzbieta,Furman, Bart?omiej
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p. 1651 - 1658
(2014/02/14)
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- Mesoporous aluminosilicate-catalyzed Mukaiyama aldol reaction of aldehydes 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 aldehydes and acetals with silyl enol ethers or ketene silyl acetals to give the corresponding aldol adducts in moderate to high yields. The remarkable high catalytic activity of Al-MCM-41 over amorphous silica-alumina and aluminum-free mesoporous silicate was observed in the reaction. The solid acid catalyst could be recovered easily by filtration and the recovered catalyst was reusable in the same reactions without a significant loss of catalytic activity.
- Ito, Suguru,Tanuma, Kenji,Matsuda, Kohei,Hayashi, Akira,Komai, Hirotomo,Kubota, Yoshihiro,Asami, Masatoshi
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p. 8498 - 8504
(2014/12/11)
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- Strong Lewis acid air-stable cationic titanocene perfluoroalkyl(aryl) sulfonate complexes as highly efficient and recyclable catalysts for C-C bond forming reactions
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A series of strong Lewis acid air-stable titanocene perfluoroalkyl(aryl) sulfonate complexes Cp2Ti(OH2)2(OSO 2X)2·THF (X = C8F17, 1·THF; X = C4F9, 2·H2O· THF; X = C6F5, 3) were successfully synthesized by the treatment of Cp2TiCl2 with C8F 17SO3Ag, C4F9SO3Ag and C6F5SO3Ag, respectively. In contrast to well-known titanocene bis(triflate), these complexes showed no change in open air over three months. TG-DSC analysis showed that 1·THF, 2·H 2O·THF and 3 were thermally stable at 230 °C, 220°C and 280°C, respectively. Conductivity measurements showed that these complexes underwent ionic dissociation in CH3CN solution. X-ray analysis results confirmed that 2·H2O·THF and 3 were cationic. ESR spectra showed that the Lewis acidity of 1·THF (1.06 eV) was higher than that of Sc3+ (1.00 eV) and Y3+ (0.85 eV). UV/Vis spectra showed a significant red shift due to the strong complex formation between 10-methylacridone and 2·H2O·THF. Fluorescence spectra showed that the Lewis acidity of 2 (λem = 477 nm) was higher than that of Sc3+ (λem = 474 nm). These complexes showed high catalytic ability in various carbon-carbon bond forming reactions. Moreover, they show good reusability. Compared with 1·THF, 2·H2O·THF and 3 exhibit higher solubility and better catalytic activity, and will find broad applications in organic synthesis. This journal is the Partner Organisations 2014.
- Li, Ningbo,Wang, Jinying,Zhang, Xiaohong,Qiu, Renhua,Wang, Xie,Chen, Jinyang,Yin, Shuang-Feng,Xu, Xinhua
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supporting information
p. 11696 - 11708
(2014/07/22)
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- Intermolecular gold(I)-catalyzed alkyne carboalkoxylation reactions for the multicomponent assembly of β-alkoxy ketones
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A new gold(I)-catalyzed multicomponent synthesis of β-alkoxy ketones from aldehydes, alcohols, and alkynes is described. This atom economical synthesis was achieved through the use of the gold complex (SPhos)AuNTf 2 as a catalyst, and allows for the preparation of a diverse array of β-alkoxy ketone products. Mechanistic studies illustrate that these reactions proceed via gold(I)-catalyzed hydrolysis of the alkyne to an aryl ketone, which then undergoes an aldol reaction with an oxocarbenium ion generated in situ from the aldehyde and alcohol components.
- Schultz, Danielle M.,Babij, Nicholas R.,Wolfe, John P.
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p. 3451 - 3455
(2013/03/13)
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- An alternative approach to direct aldol reaction based on gold-catalyzed methoxyl transfer
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A mild and catalyzed alternative to the direct aldol reaction has been developed based on the gold-catalyzed methoxy group transfer from dimethyl acetals to terminal alkynes. Due to the simultaneous activation of the acetals, this aldol approach is only functional for acetals but not aldehydes. A ligand effect from the gold complex has also been observed. Copyright
- Zhang, Moran,Wang, Yunxia,Yang, Yang,Hu, Xiangdong
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experimental part
p. 981 - 985
(2012/06/30)
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- Cationic iridium complex is a new and efficient Lewis acid catalyst for aldol and Mannich reactions
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A cationic iridium complex [Ir(cod)2]SbF6 was found to be a new and efficient Lewis acid catalyst for Mukaiyama aldol and Mannich reactions. Aldehydes react smoothly with silyl enol ethers to give β-siloxy ketones in the presence of 0.5 mol % of [Ir(cod)2]SbF6. The reaction of N-alkyl arylaldimines with ketene silyl acetals in the presence of 5 mol % [Ir(cod)2]SbF6/P(OPh)3 gave β-amino esters. After Mannich reaction was complete, stirring of the reaction mixture for 24 h led to cyclization to give β-lactam. The reaction of N-aryl benzaldimine with silyl enol ether derived from acetophenone gave a tetrahydroquinoline derivative as a single diastereomer.
- Onodera, Gen,Toeda, Takayuki,Toda, Nou-No,Shibagishi, Daigo,Takeuchi, Ryo
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experimental part
p. 9021 - 9031
(2011/01/04)
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- Mesoporous aluminosilicate-catalyzed Sakurai allylation and Mukaiyama aldol reaction of acetals
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In the presence of a catalytic amount of mesoporous aluminosilicate (Al-MCM-41), both allyltrimethylsilane and silyl enol ether reacted with various acetals under mild reaction conditions to afford the corresponding homoallyl ethers and β-alkoxy ketones,
- Ito, Suguru,Hayashi, Akira,Komai, Hirotomo,Kubota, Yoshihiro,Asami, Masatoshi
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experimental part
p. 4243 - 4245
(2010/09/07)
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- Organotin perfluorooctanesulfonates as air-stable Lewis acid catalysts: Synthesis, characterization, and catalysis
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The reactions of 1,3-dichloro-1,1,3,3-tetrabutyldistannoxane and di-alkyltin dihalides with silver perfluoro-octanesulfonate provided the corresponding sulfonates as hydrates. The number of water molecules (n) of hydration was dependent on the conditions. The distannoxane derivative was identified as n from 0.5 to 6, while in the hydrated mononuclear species and DMSO complexes n varied widely from 4 to 13. 119Sn NMR spectroscopy and conductivity measurements indicated the ionic dissociation of these compounds in solution. These compounds exhibited unusually high solubility in polar organic solvents. The ionic dissociation together with facile hydration probably causes the unusual solubility. The Lewis acidity of these compounds was found to be high among organotin derivatives on the basis of ESR spectra of Superoxide/ metal-ion complexes. In contrast to well-known organotin Inflates, these compounds suffered no hydrolysis upon storage in open air. The high catalytic activity of the distannoxane 1 was exemplified for various carboncarbon bond-forming reactions, such as Mukaiyama-aldol as well as -Michael reactions and allylation of aldehydes.
- An, De Lie,Peng, Zhihong,Orita, Akihiro,Kurita, Akinobu,Man-E, Sumiyo,Ohkubo, Kei,Li, Xingshu,Fukuzumi, Shunichi,Otera, Junzo
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p. 1642 - 1647
(2007/10/03)
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- A unique catalyst effects the rapid room-temperature cross-coupling of organozinc reagents with carboxylic acid fluorides, chlorides, anhydrides, and thioesters
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We have identified a catalyst capable of effecting the rapid, room-temperature cross-coupling between acid fluorides and diorganozinc reagents. The use of acid fluorides as electrophilic partners allows this reaction to tolerate epimerizable functionality as well as β leaving groups. The same catalyst is also capable of cross-coupling acid chlorides, acyl cyanides, anhydrides, thioesters, and pyridyl esters. Noteworthy is the ability of the reaction to successfully transfer both groups from the organometalic fragment. Copyright
- Zhang, Yongda,Rovis, Tomislav
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p. 15964 - 15965
(2007/10/03)
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- Selective aldol reactions of acetals on mesoporous silica catalyst
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Mukaiyama-aldol reactions of carbonyl compounds with silyl enol ethers were well catalyzed on siliceous mesoporous materials (MCM-41). The reactivity of acetals was much higher than that of aldehyde. The reactions proceeded selectively at 273-298 K on the
- Ishitani, Haruro,Iwamoto, Masakazu
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p. 299 - 301
(2007/10/03)
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- Single-pass reaction column system with super br?nsted acid-loaded resin
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Various acid-promoted reactions gave the desired products in high yields by passing a solution of reactants through a reaction column packed with polystyrene-bound super Br?nsted acid (1) just once. Polar and nonpolar organic solvent-swellable 1 is much superior to Nafion SAC-13 (2) as a Br?nsted acid-loaded resin packed in the column.
- Ishihara, Kazuaki,Hasegawa, Aiko,Yamamoto, Hisashi
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p. 1296 - 1298
(2007/10/03)
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- Chemoselective aldol reaction of silyl enolates catalyzed by Mgl2 etherate
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(matrix presented) Mukaiyama-type aldol coupling of typical silyl enolates 2-4 with aryl or vinyl aldehydes and acetals was realized in the presence of 1-5 mol % of MgI2 etherate (1) in a mild, efficient, and highly chemoselective manner. Iodid
- Li, Wei-Dong Z.,Zhang, Xing-Xian
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p. 3485 - 3488
(2007/10/03)
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- Reformatsky-type reaction of α-haloketones promoted by titanium tetraiodide
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Titanium(IV) tetraiodide induces a Reformatsky-type reaction of α-iodoketones with carbonyl compounds to give β-hydroxy ketones in good to high yields.
- Shimizu, Makoto,Kobayashi, Fumiko,Hayakawa, Ryuuichirou
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p. 9591 - 9595
(2007/10/03)
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- Polymer-supported dicyanoketene acetal as a π-acid catalyst: Monothioacetalization and carbon-carbon bond formation of acetals
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Polymeric dicyanoketene acetals (DCKA) were synthesized by copolymerization of styrene and divinylbenzene or ethylene glycol dimethacrylate. These novel polymers could be used successfully as recyclable π-acid catalysts in monothioaCetalization or carbon-carbon bond forming reaction of acetals.
- Tanaka, Nobuyuki,Miura, Tsuyoshi,Masaki, Yukio
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p. 1010 - 1016
(2007/10/03)
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- Polymer-supported acid catalyst in the carbon-carbon bond formation of acetals with silylated nucleophiles
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Polymeric dicyanoketene acetal (DCKA), which was synthesized by co- polymerization of styrene monomer bearing dicyanoketene acetal functionality and ethylene glycol dimethacrylate, was found to be an effective and recyclable catalyst in the carbon-carbon bond formation of acetals with silylated nucleophiles.
- Tanaka, Nobuyuki,Masaki, Yukio
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p. 1277 - 1279
(2007/10/03)
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- Parallel recognition by virtue of differentiation between carbonyls, acetals and enones
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'Parallel recognition', a new concept for compacting synthetic processes in which different transformations are performed simultaneously on separate reaction sites, has been advance. Ketones/α,β-enones and aldehydes/acetals are able to react selectively w
- Chen, Jian-Xie,Sakamoto, Katsumasa,Orita, Akihiro,Otera, Junzo
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p. 8411 - 8420
(2007/10/03)
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- Bismuth(III) Triflate: A Water-Stable Equivalent of Trimethylsilyl Triflate for the Catalysis of Mukaiyama Aldol Reactions
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Bismuth tris-trifluoromethanesulfonate (1) has been found to be an efficient catalyst for the Mukaiyama aldol-type reactions.The catalytic activity of this catalyst is higher than the one previously reported for the rare earth triflates M(OTf)3 (M = Sc, L
- Roux, C. Le,Ciliberti, L.,Laurent-Robert, H.,Laporterie, A.,Dubac, J.
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p. 1249 - 1251
(2007/10/03)
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- Catalytic Activity of Tetracyanoethylene in the Reactions of Aldehydes, Ketones and Acetals with Silylated Nucleophiles
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Tetracyanoethylene catalyses the reactions of aldehydes, ketones and acetals with silylated carbon and hydrogen-nucleophiles to promote carbon-carbon bond formation and reduction under neutral conditions.
- Miura, Tsuyoshi,Masaki, Yukio
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p. 1659 - 1660
(2007/10/02)
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- Photorearrangement and electron transfer photooxidation of 1-acetoxy-1,2-diphenylcyclopropane
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Direct irradiation of the title compound 4 in hexane led to 1,3-diphenyl-1,4-pentanedione (5) in 75 % yield. This is explained through carbonyl-oxygen bond cleavage (process iii), to afford a cyclopropyloxy radical (I) which rearranges to a β-carbonyl radical (II) prior to in cage recombination. In methanol, the solvent addition product 6 was obtained as byproduct. It formation is rationalized by means of the symmetrical cationic intermediate IV, on the basis of deuterium incorporation to C(1) and C(3) in MeOD. Photosensitization by acetone resulted exclusively in trans to cis isomerization, via the diradical III (process i). Finally electron transfer activation by means of cerium(IV) ammonium nitrate (CAN) or excited triphenylpyrylium tetrafluoroborate (TPT) gave rise to chalcone (7) or the β-functionalized ketones 8 or 9. These products must arise from a common cationic precursor (V), after cleavage of the central carbon-carbon bond (process i) in the radical cation 4+. From the preparative point of view, the obtention of diketone 5 in 75% yield by photolysis of 4 in hexane is exploitable, since it constitutes a synthetic equivalent of the addition of acyl anions or acyl radicals to enones.
- Algarra, Felipe,Baldovi, Maria V.,Garcia, Hermenegildo,Miranda, Miguel A.,Primo, Jaime
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p. 10897 - 10902
(2007/10/02)
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- TELLURIUM TETRACHLORIDE AS A MILD DEPROTECTION REAGENT FOR ACETALS AND THIOACETALS
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On treatment with tellurium tetrachloride in dichloromethane at room temperature, acetals and thioacetals are easily cleaved to regenerate original carbonyl compounds in good yields.
- Tani, Hiroyuki,Inamasu, Tokuo,Masumoto, Kazunori,Tamura, Rui,Shimizu, Hiroshi,Suzuki, Hitomi
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p. 261 - 266
(2007/10/02)
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- Reversal Phenomena of the Preferential Activation of Aldehydes to the Corresponding Acetals under Non-Basic Conditions. The Chemoselective Aldol Reaction of Aldehydes with t-Butyldimethylsilyl Enol Ethers Using TBSCl-InCl3 as a Catalyst
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In the presence of a catalytic amount of t-butyldimethylsilyl chloride (TBSCl) and indium(III) chloride (InCl3), aldehydes smoothly react with t-butyldimethylsilyl enol ethers to afford the corresponding aldol adducts in good yields whereas acetals do not
- Mukaiyama, Teruaki,Ohno, Takashi,Han, Jeong Sik,Kobayashi, Shu
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p. 949 - 952
(2007/10/02)
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- Efficient Activation of Acetals, Aldehydes, and Imines toward Silylated Nucleophiles by the Combined Use of Catalytic Amounts of 2 and TMS-CN under Almost Neutral Conditions
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In the presence of catalytic amount of a transition metal compound such as 2, Co(acac)2, or NiCl2, trimethylsilyl cyanide smoothly reacts with acetals to form α-methoxy carbonitriles in good yields.In the coexistence of catalytic amounts of Rh
- Soga, Tsunehiko,Takenoshita, Haruhiro,Yamada, Masaaki,Mukaiyama, Teruaki
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p. 3122 - 3131
(2007/10/02)
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- Efficient Activation of Acetals toward Nucleophiles with 2 Catalyst. New Method for the Preparation of Aldols from Acetals and Silyl Enol Ethers by the Combined Use of Catalytic Amounts of 2 and Trimethylsilyl Cyanide
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In the presence of a catalytic amount of 2, di-μ-chloro-bis(1,5-cyclooctadiene)dirhodium, trimethylsilyl cyanide smoothly reacts with acetals derived from aliphatic, unsaturated and aromatic aldehydes to form the corresponding α-cyano derivativ
- Mukaiyama, Teruaki,Soga, Tsunehiko,Takenoshita, Haruhiro
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p. 1273 - 1276
(2007/10/02)
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- Crossed aldol-type reactions catalyzed by rhodium complexes
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Crossed aldol-type reactions of enol trimethylsilyl ethers with aldehydes and ketones are smooth when carried out with a catalytic amount of a rhodium complex, Rh4(CO)12 or X (X=PF6 and ClO4; COD=cycloocta-1,5-diene, DPPB=1,4-bis(diphenylphosphino)butane), under neutral conditions.A suitable catalyst enables the isolation of three different types of aldol reaction product, β-trimethylsiloxy ketones, β-hydroxy ketones, and α,β-unsaturated ketones.Rh4(CO)12 and ClO4 also catalyze the reaction of enol trimethylsilyl ethers with acetals or ketals, whereas PF6 does not.When ClO4 is used as the catalyst, this type of aldol reaction is extended to the one-pot synthesis of trisubstituted furans from enol trimethylsilyl ether and α-trimethylsiloxy acetal.
- Sato, Susumu,Matsuda, Isamu,Izumi, Yusuke
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p. 223 - 238
(2007/10/02)
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- Electrogenerated Acid-Catalyzed Reactions of Acetals, Aldehydes, and Ketones with Organosilicon Compounds, Leading to Aldol Reactions, Allylations, Cyanations, and Hydride Additions
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Exquisite use of electrogenerated acid (EG acid) in the silicon-mediated acid-catalyzed reactions; e.g., aldol reactions, allylations, cyanations, and hydride additions is described.The aldol reaction of acetals 1 with enol trimethylsilyl ethers 3 and 1,2-bis(trimethylsiloxy)alkenes 4 gives the corresponding adducts 5 and 6, respectively.The reaction proceeds smoothly with EG acid derived from perchlorate salts such as LiClO4, n-Bu4NClO4, and Mg(ClO4)2 in dichloromethane using platinum electrodes.The amount of electricity required to complete the reaction implies a cationic process which is mediated by the trimethylsilyl moiety.This aldol reaction is further developed with unprotected carbonyl compounds 2 with 3, giving the trimethylsilyl ethers of the adducts 7.Further utility of this EG acid as a catalyst for a chain reaction is exemplified by the successful application in the following conversions: (1) The allylation of acetals 1 with allyltrimethylsilane (8) to give 9, (2) the cyanation of acetals 1 and unmasked 2 with trimethylsilyl cyanide (10) to give 11, 12, and 13, and (3) the hydride addition of acetals 1 with triethylsilane (14) to give 15.
- Torii, Sigeru,Inokuchi, Tsutomu,Takagishi, Sadahito,Horike, Hirofumi,Kuroda, Hideki,Uneyama, Kenji
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p. 2173 - 2188
(2007/10/02)
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- Stereoselective Cross-Aldol Reactions of Silyl Enol Ethers with Acetals Catalyzed by Iodotrimethylsilane
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Iodotrimethylsilane catalyzes effectively erythroselective aldol type condensation of silyl enol ethers with acetals.
- Sakurai, Hideki,Sasaki, Koshi,Hosomi, Akira
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p. 3195 - 3196
(2007/10/02)
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