- Asymmetric carbon-carbon bond forming reactions catalysed by metal(II) bis(oxazoline) complexes immobilized using supported ionic liquids
-
A series of bis(oxazoline) metal(II) complexes has been supported on silica and carbon supports by non-covalent immobilisation using an ionic liquid. The catalytic performance of these solids was compared for the enantioselective Diels-Alder reaction between N-acryloyloxazolidinone and cyclopentadiene and the Mukaiyama-aldol reaction between methyl pyruvate and 1-methoxy-1- trimethylsilyloxypropene. In both reactions the enantioselectivity was strongly influenced by the choice of support displaying enantioselectivies (ee values) up to 40% higher than those conducted under homogeneous reaction conditions.
- Goodrich,Hardacre,Paun,Ribeiro,Kennedy,Lourenco,Manyar,De Castro, C. A. Nieto,Besnea,Parvulescu
-
-
Read Online
- Efficient α-chlorination of carbonyl containing compounds under basic conditions using methyl chlorosulfate
-
An efficient method for the α-chlorination of ketones under basic conditions is described using methyl chlorosulfate. Its applicability for the chlorination of other functional groups has also been studied and it is equally useful for the synthesis of α-chloroesters and amides. Methyl chlorosulfate is described for the first time as a positive chlorine source. Some aldol reactions which occur during the chlorination of some substrates are also reported.
- Silva, Saúl,Maycock, Christopher D.
-
supporting information
p. 1233 - 1238
(2018/02/27)
-
- Unprecedented alkylation of silicon enolates with alcohols via carbenium ion formations catalyzed by tin hydroxide-embedded montmorillonite
-
The solid acid, tin hydroxide-embedded montmorillonite, catalyzes the unprecedented alkylation of various silicon enolates with primary, secondary and tertiary benzylic alcohols as well as secondary allylic alcohols. The acid catalysis of Sn-Mont was not only higher than that of the other ion-exchanged montmorillonites (M-Mont; M?=?H, Ti, Fe and Al), but also higher than that of the typical homogeneous acid catalysts such as BF3·OEt2, TMSOTf and TfOH.
- Tandiary, Michael Andreas,Asano, Masashi,Hattori, Taiki,Takehira, Satoshi,Masui, Yoichi,Onaka, Makoto
-
supporting information
p. 1925 - 1928
(2017/04/27)
-
- Isopropylmagnesium chloride-promoted unilateral addition of Grignard reagents to β-diketones: One-pot syntheses of β-tertiary hydroxyl ketones or 3-substituted cyclic-2-enones
-
The regioselective unilateral additions of Grignard reagents to acyclic or cyclic β-diketones were effectively promoted by sub-stoichiometric amounts of i-PrMgCl to afford β-tertiary hydroxyl ketones or 3-substituted cyclic-2-enones, respectively. Also, the addition of Grignard reagents to acyclic β-diketones followed by a reaction with cyclic β-diketones in a one-pot process was put forward. The reaction mechanism was discussed in detail to explain the high regioselectivity via chemical experiments, hydrogen-deuterium exchange and mass spectrometry.
- Yuan, Rui,Zhao, Dan,Zhang, Li-Yuan,Pan, Xiang,Yang, Yan,Wang, Pei,Li, Hong-Feng,Da, Chao-Shan
-
supporting information
p. 724 - 728
(2016/01/12)
-
- One-Pot Synthesis of β,β-Disubstituted α,β-Unsaturated Carbonyl Compounds
-
TiCl4-promoted aldol reaction of ketones as aldol acceptors followed by elimination of the titanoxy group from the Ti-aldolates affords β,β-disubstituted α,β-unsaturated carbonyl compounds in a one-pot procedure. The use of additives, such as DMF, N,N,N′,N′-tetramethylethylenediamine, and pyridine, in the elimination step was found to be important.
- Sugiura, Masaharu,Ashikari, Yasuhiko,Nakajima, Makoto
-
p. 8830 - 8835
(2015/09/15)
-
- Mukaiyama aldol reactions catalyzed by a trimeric organo aluminum(III) alkoxide
-
Mukaiyama aldol reactions of enol ethers with a variety of aldehydes and ketones are efficiently catalyzed at 0-25 °C by the sterically bulky trimeric organo aluminum(III) alkoxide 1 synthesized via the reaction of 3 equiv of AlMe3 with tripodal tris(2-hydroxy-3-tert-butyl-5-methylphenyl) methane and the elimination of 3 equiv of methane. Comparisons of its catalytic properties with the less sterically hindered analogue 2, the more sterically hindered analogue 3, a monomeric aluminum near-analogue 4, and a dimeric alumatrane 5 revealed that 1 possesses superior activity.
- Kim, So Han,Yoon, Sungwoo,Kim, Youngjo,Verkade, John G.
-
p. 1193 - 1206
(2014/09/30)
-
- The mukaiyama aldol reactions for congested ketones catalyzed by solid acid of tin(IV) ion-exchanged montmorillonite
-
Tin(IV) ion-exchanged montmorillonite (Sn-Mont) was found to be an excellent solid acid catalyst for the Mukaiyama aldol reactions of congested ketones with silicon enolates from ketones as well as esters. It was disclosed that Sn-Mont was far more active than other metal ion-or proton-exchanged montmorillonites and typical homogeneous acid catalysts such as TMSOTf and BF3?OEt2.
- Takehira, Satoshi,Masui, Yoichi,Onaka, Makoto
-
supporting information
p. 498 - 500
(2014/04/17)
-
- An efficient Cu(II)-bis(oxazoline)-based polymer immobilised ionic liquid phase catalyst for asymmetric carbon-carbon bond formation
-
The asymmetric Diels-Alder reaction between N-acryloyloxazolidinone and cyclopentadiene and the Mukaiyama-aldol reaction between methylpyruvate and 1-phenyl-1-trimethylsilyloxyethene have been catalysed by heterogeneous copper(II)-bis(oxazoline)-based pol
- Doherty, Simon,Knight, Julian G.,Ellison, Jack R.,Goodrich, Peter,Hall, Leanne,Hardacre, Christopher,Muldoon, Mark J.,Park, Soomin,Ribeiro, Ana,De Castro, Carlos Alberto Nieto,Lourenco, Maria Jose,Davey, Paul
-
p. 1470 - 1479
(2014/03/21)
-
- Synthesis of silaoxazolinium salts bearing weakly coordinating anions: Structures and catalytic activities in the aldol reaction
-
The synthesis and structures of silaoxazolinium salts 2 and their application to the catalytic Mukaiyama aldol reaction are described. The reaction of (N-amidomethyl)dimethylchlorosilane (1a) or (N-amidomethyl) bis(trimethylsilyl)chlorosilane (1b) with me
- Chandra Sheker Reddy, Anugu,Chen, Zhang,Hatanaka, Tohru,Minami, Tatsuya,Hatanaka, Yasuo
-
p. 3575 - 3582
(2013/07/26)
-
- Sequential one-pot addition of excess aryl-grignard reagents and electrophiles to O-alkyl thioformates
-
The sequential addition of aromatic Grignard reagents to O-alkyl thioformates proceeded to completion within 30s to give aryl benzylic sulfanes in good yields. This reaction may begin with the nucleophilic attack of the Grignard reagent onto the carbon atom of the O-alkyl thioformates, followed by the elimination of ROMgBr to generate aromatic thioaldehydes, which then react with a second molecule of the Grignard reagent at the sulfur atom to form arylsulfanyl benzylic Grignard reagents. To confirm the generation of aromatic thioaldehydes, the reaction between O-alkyl thioformates and phenyl Grignard reagent was carried out in the presence of cyclopentadiene. As a result, hetero-Diels-Alder adducts of the thioaldehyde and the diene were formed. The treatment of a mixture of the thioformate and phenyl Grignard reagent with iodine gave 1,2-bis(phenylsulfanyl)-1,2-diphenyl ethane as a product, which indicated the formation of arylsulfanyl benzylic Grignard reagents in the reaction mixture. When electrophiles were added to the Grignard reagents that were generated insitu, four-component coupling products, that is, O-alkyl thioformates, two molecules of Grignard reagents, and electrophiles, were obtained in moderate-to-good yields. The use of silyl chloride or allylic bromides gave the adducts within 5min, whereas the reaction with benzylic halides required more than 30min. The addition to carbonyl compounds was complete within 1min and the use of lithium bromide as an additive enhanced the yields of the four-component coupling products. Finally, oxiranes and imines also participated in the coupling reaction. Into the melting pot: The addition of excess aryl Grignard reagents and electrophiles to O-alkyl thioformates gives aryl sulfanes through four-component coupling reactions (see scheme). These reactions may involve the formation of aromatic thioaldehydes and aryl-benzylic Grignard reagents as intermediates. For addition to carbonyl compounds, the use of lithium halides as an additive enhanced the efficiency of the reaction. Copyright
- Murai, Toshiaki,Morikawa, Kenta,Maruyama, Toshifumi
-
p. 13112 - 13119
(2013/10/01)
-
- Added-metal-free catalytic nucleophilic addition of Grignard reagents to ketones
-
On the basis of the investigation of the combinational effect of quaternary ammonium salts and organic bases, an added-metal-free catalytic system for nucleophilic addition reactions of a variety of Grignard reagents to diverse ketones in THF solvent has been developed to produce tertiary alcohols in good to excellent yields. By using tetrabutylammonium chloride (NBu4Cl) as a catalyst and diglyme (DGDE) as an additive, this system strongly enhances the efficiency of addition at the expense of enolization and reduction. NBu 4Cl should help to shift the Schlenk equilibrium of Grignard reagents to the side of dimeric Grignard reagents to favor the additions of Grignard reagents to ketones via a favored six-membered transition state to form the desired tertiary alcohols, and DGDE should increase the nucleophilic reactivities of Grignard reagents by coordination. This catalytic system has been applied in the efficient synthesis of Citalopram, an effective U.S. FDA-approved antidepressant, and a recyclable version of this catalytic synthesis has also been devised.
- Zong, Hua,Huang, Huayin,Liu, Junfeng,Bian, Guangling,Song, Ling
-
experimental part
p. 4645 - 4652
(2012/07/03)
-
- Ionic liquid catalysed synthesis of β-hydroxy ketones
-
Different acidic ionic liquids (ILs; namely, 1-methylimidazolium tetrafluoroborate, 1-methylimidazolium trifluoroacetate, N-methyl-2-pyrrolidone hydrogen sulfate, N,N,N-trioctyl-n-butanesulfonic acid ammonium hydrogen sulfate, 1-methyl-3-(3-sulfobutyl)imidazolium hydrogen sulfate) and basic ILs (namely, 1,1,3,3-tetramethylguanidinium lactate and choline hydroxide) were tested as catalysts for the aldol reaction. The choline hydroxide catalysed reaction gave high yield (94.3%) and selectivity of the 4-hydroxy-4-phenylbutan- 2-one after a short reaction time (15min) at 0°C. This article demonstrates the potential of choline hydroxide, which is a derivative of choline and a naturally occurring water-soluble essential nutrient, as a highly active and selective green catalyst.
- Karmee, Sanjib Kumar,Hanefeld, Ulf
-
experimental part
p. 1118 - 1123
(2012/04/17)
-
- Nucleophilic trifluoromethylation with organoboron reagents
-
Potassium trialkoxy(trifluoromethyl)borates are shown to behave as convenient reagents for nucleophilic trifluoromethylation of non-enolizable aldehydes and N-tosylimines to give CF3-substituted alcohols and N-tosylamines in good yields.
- Levin, Vitalij V.,Dilman, Alexander D.,Belyakov, Pavel A.,Struchkova, Marina I.,Tartakovsky, Vladimir A.
-
supporting information; experimental part
p. 281 - 284
(2011/02/26)
-
- Zinc(II)-catalyzed addition of grignard reagents to ketones
-
(Figure presented) The addition of organometallic reagents to carbonyl compounds has become a versatile method for synthesizing tertiary and secondary alcohols via carbon-carbon bond formation. However, due to the lack of good nucleophilicity or the presence of strong basicity of organometallic reagents, the efficient synthesis of tertiary alcohols from ketones has been particularly difficult and, thus, limited. We recently developed highly efficient catalytic alkylation and arylation reactions to ketones with Grignard reagents (RMgX: R = alkyl, aryl; X = Cl, Br, I) using ZnCl2, Me3SiCH 2MgCl, and LiCl, which effectively minimize problematic side reactions. In principle, RMgBr and RMgI are less reactive than RMgCl for the addition to carbonyl compounds. Therefore, this novel method with homogeneous catalytic ZnCl2·Me3SiCH2MgCl·LiCl is quite attractive, since RMgBr and RMgI, which are easily prepared and/or commercially available, like RMgCl, can be applied successfully. As well as ketones and aldehydes, aldimines were effectively applied to this catalysis, and the corresponding secondary amines were obtained in high yield. With regard to mechanistic details concerning β-silyl effect and salt effect, in situ-prepared [R(Me3SiCH2)2Zn] -[Li]+[MgX2]m[LiCl]n (X = Cl/Br/I) is speculated to be a key catalytic reagent to promote the reaction effectively. The simplicity of this reliable ZnCl2·Me 3SiCH2MgCl·LiCl system in the addition of Grignard reagents to carbonyl compounds might be attractive for industrial as well as academic applications.
- Hatano, Manabu,Ito, Orie,Suzuki, Shinji,Ishihara, Kazuaki
-
supporting information; experimental part
p. 5008 - 5016
(2010/10/04)
-
- Development of N,N-bis(perfluoroalkanesulfonyl)squaramides as new strong Br?nsted acids and their application to organic reactions
-
New strong Br?nsted acids derived from a squaric acid scaffold bearing different perfluoroalkanesulfonyl groups have been developed and applied to several organic reactions. These squaramides are bench-stable and exhibit much higher reactivities in several organic reactions than squaric acid itself. N,N-Bis(trifluoromethanesulfonyl)squaramide 2a was applied to the Mukaiyama aldol reaction and Mukaiyama Michael reaction. Mechanistic studies revealed that the Br?nsted acid might be the predominant catalyst through direct protonation of carbonyl compound by the acid itself rather than the silylated Br?nsted acid. The utility of this acid 2a was further extended to Hosomi-Sakurai allylation of aldehydes and a carbonyl-ene reaction. Furthermore, other squaramides 2b and c bearing longer perfluoroalkyl chains have been developed, which are also bench-stable and displayed similar reactivities with squaramide 2a in several organic reactions.
- Cheon, Cheol Hong,Yamamoto, Hisashi
-
supporting information; experimental part
p. 4257 - 4264
(2010/07/06)
-
- Zinc(ii)-catalyzed Grignard additions to ketones with RMgBr and RMgI
-
Highly efficient alkylations and arylations of ketones with Grignard reagents (RMgBr and RMgI) have been developed using catalytic ZnCl2, Me3SiCH2MgCl, and LiCl. Tertiary alcohols were obtained in high yields with high chemoselectivities, while minimizing undesired side products produced by reduction and enolization.
- Hatano, Manabu,Ito, Orie,Suzuki, Shinji,Ishihara, Kazuaki
-
scheme or table
p. 2674 - 2676
(2010/07/08)
-
- Catalytic enantioselective synthesis of sterically demanding alcohols using di(2°-alkyl)zinc prepared by the refined Charette's method
-
A highly practical, catalytic enantioselective 2°-alkyl addition to aldehydes and ketones was developed. Chiral phosphoramide ligand (1) with salt-free and solvent-free di(2°-alkyl)zinc reagents prepared from (2°-alkyl)MgCl was essential. The Royal Society of Chemistry 2010.
- Hatano, Manabu,Mizuno, Tomokazu,Ishihara, Kazuaki
-
supporting information; experimental part
p. 5443 - 5445
(2010/10/04)
-
- A new Br?nsted acid derived from squaric acid and its application to Mukaiyama aldol and Michael reactions
-
Bis-N-trifluoromethanesulfonyl squaramide was prepared as a new bench-stable strong Br?nsted acid and applied to the Br?nsted acid-catalyzed Mukaiyama aldol and Michael reactions with silyl enol ethers. The resulting Mukaiyama aldol products of aldehydes
- Cheon, Cheol Hong,Yamamoto, Hisashi
-
experimental part
p. 3555 - 3558
(2009/10/26)
-
- Efficient heterogeneous asymmetric catalysis of the Mukaiyama aldol reaction by silica- and ionic liquid-supported lewis acid copper(II) complexes of bis(oxazolines)
-
Lewis acid complexes based on copper(II) and an imidazolium-tagged bis(oxazoline) have been used to catalyse the asymmetric Mukaiyama aldol reaction between methyl pyruvate and 1-methoxy-l-trimethylsilyloxypropene under homogeneous and heterogeneous conditions. Although the ees obtained in ionic liquid were similar to those found in dichloromethane, there was a significant rate enhancement in the ionic liquid with reactions typically reaching completion within 2 min compared with only 55% conversion after 60 min in dichloromethane. However, this rate enhancement was offset by lower chemo-selectivity in ionic liquids due to the formation of 3-hydroxy-1,3- diphenylbutan-1-one as a by-product. Supporting the catalyst on silica or an imidazolium-modified silica using the ionic liquid or in an ionic liquid-diethyl ether system completely suppressed the formation of this by-product without reducing the enantioselectivity. Although the heterogeneous systems were characterised by a drop in catalytic activity the system could be recycled up to five times without any loss in conversion or ee.
- Doherty,Goodrich,Hardacre,Parvulescu,Paun
-
body text
p. 295 - 302
(2009/04/08)
-
- Polymer-supported synthesis of α- and β-hydroxyketones through the formation of 1,3-dithiane intermediates
-
The synthesis of polymer-supported 2-monosubstituted 1,3-dithianes from soluble copolymers bearing 1,3-propanedithiol groups, their lithiation, reactions with electrophiles such as aldehydes, ketones, α,β- unsaturated ketones and oxiranes, and cleavage of
- Bertini, Vincenzo,Lucchesini, Francesco,Pocci, Marco,Alfei, Silvana,Idini, Barbara
-
body text
p. 1141 - 1144
(2009/04/06)
-
- Highly alkyl-selective addition to ketones with magnesium ate complexes derived from Gignard reagents
-
(Chemical Equation Presented) A highly efficient alkyl-selective addition to ketones with magnesium ate complexes derived from Grignard reagents and alkyllithiums is described. The nucleophilicity of R in R3MgLi is remarkably increased compared to that of the original RLi or RMgX, while the basicity of R3MgLi is decreased. Furthermore, a highly R-selective addition to ketones is demonstrated using RMe2MgLi in place of R 3MgLi.
- Hatano, Manabu,Matsumura, Tokihiko,Ishihara, Kazuaki
-
p. 573 - 576
(2007/10/03)
-
- Strong counteranion effects on the catalytic activity of cationic silicon lewis acids in Mukaiyama aldol and Diels-Alder reactions
-
(Graph Presented) A toluene-coordinated silyl borate, [Et 3Si(toluene)]B(C6F5)4, demonstrated catalytic activities significantly higher than those of Me3SiOTf and Me3SiNTf2 in Mu
- Hara, Kenji,Akiyama, Ryuto,Sawamura, Masaya
-
p. 5621 - 5623
(2007/10/03)
-
- On the paradox of TiCl4 reducing power: Pinacol coupling and two-carbon homologation of carbonyl compounds
-
TiCl4/DIPEA/CH2Cl2 reducing system promotes pinacol coupling and/or reduction to alcohol of aromatic aldehydes and carbonyl compounds activated towards reduction by an electron withdrawing group. In addition, bis homologation of these substrates is observed. An inner-sphere electron transfer from TiCl4 to DIPEA accounts for the products distribution.
- Clerici, Angelo,Pastori, Nadia,Porta, Ombretta
-
p. 1825 - 1827
(2007/10/03)
-
- A high yield procedure for the Me3SiNTf2-induced carbon-carbon bond-forming reactions of silyl nucleophiles with carbonyl compounds: The importance of addition order and solvent effects
-
We demonstrate the efficiency of Me3SiNTf2 (0.3-1.0 mol%) as a strong Lewis acid catalyst for the Mukaiyama aldol and Sakurai-Hosomi allylation reactions, and that the slow addition of carbonyl compounds to a solution of acid catalys
- Ishihara,Hiraiwa,Yamamoto
-
p. 1851 - 1854
(2007/10/03)
-
- 1,3-Dimethyl-2-phenylbenzimidazoline (DMPBI)-acetic acid: An effective reagent system for photoinduced reductive transformation of α,β-epoxy ketones to β-hydroxy ketones
-
A combination of 1,3-dimethyl-2-phenylbenzimidazoline (DMPBI) and acetic acid has been utilized for photoinduced reductive transformation of α,β-epoxy ketones to β-hydroxy ketones. Study on photoreactions using several proton donors revealed that acetic acid is superior to other proton donors such as HCl, p-TsOH, MeOH, and water. 1,3-Dimethyl-2-phenylbenzimidazolium was produced in the reaction with acetic acid while N-benzoyl-N,N′-dimethyl-o-phenylenediamine was formed in aqueous solvents. When THF solutions containing aryl carbonyl possessing α,β-epoxy ketones and DMPBI and acetic acid were irradiated (λ > 280 nm), β-hydroxy ketones were isolated in good to excellent yields. Photosensitized conditions (λ > 340 nm) were employed for the reactions of alkyl carbonyl possessing α,β-epoxy ketones.
- Hasegawa,Chiba,Nakajima,Suzuki,Yoneoka,Iwaya
-
p. 1248 - 1252
(2007/10/03)
-
- Aluminum bis(trifluoromethylsulfonyl)amides: New highly efficient and remarkably versatile catalysts for C-C bond formation reactions
-
Superacid-derived aluminum catalysts R2AlNTf2 (2-5 mol%) are highly efficient and versatile and are suitable promoters for the allylation and pentadienylation of aldehydes, aldol reactions, aldol cross-coupling of ketones, and Michae
- Marx, Andreas,Yamamoto, Hisashi
-
p. 178 - 181
(2007/10/03)
-
- Reductive transformation of α β-epoxy ketones and other compounds promoted through photoinduced electron transfer processes with 1,3-dimethyl- 2-phenylbenzimidazoline (DMPBI)
-
Photoreactions of epoxy ketones, aromatic ketones, haloketones, and aromatic halides with 1,3-dimethyl-2-phenylbenzimidazoline (DMPBI) were studied. Photoinduced single-electron transfer from DMPBI to such substrates initiates the reactions, followed by radical rearrangement and reduction to finally give several reduced products in modest to good yields.
- Hasegawa, Eietsu,Yoneoka, Akira,Suzuki, Kumiko,Kato, Teru,Kitazume, Takashi,Yanagi, Kazuhiro
-
p. 12957 - 12968
(2007/10/03)
-
- Parallel recognition by virtue of differentiation between carbonyls, acetals and enones
-
'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
-
p. 8411 - 8420
(2007/10/03)
-
- The chromium Reformatsky reaction: Access to adjacent quarternary centers
-
α-Bromo ketones, -esters and -nitriles react with chromium dichloride and ketones in a Barbier-type reaction to yield the kinetic crossed aldol products with one or two new quarternary centers. The reaction does not require special activation of the reage
- Wessjohann, Ludger,Wild, Harry
-
p. 512 - 514
(2007/10/03)
-
- Reactions of Ketones with the Oxidizing System Aluminum Tri-tert-butylate-tert-Butyl Hydroperoxide
-
Oxidation of ketones containing primary, secondary, and tertiary carbon atoms at the α-position [dialkyl ketones, alkyl aryl ketones, and alkyl (aryl) benzyl ketones] with the system aluminum tri-tert-butylale-tert-butyl hydroperoxide is accompanied by cleavage of the carbon skeleton of the substrate via formation of α-hydroxy carbonyl and α-dicarbonyl compounds. The qualitative and quantitative composition of the reaction products indicates that the oxidation involves free radicals. Simultaneously, the oxidizing system adds across the carbonyl group of the substrate, which is followed by decomposition of aluminum-containing peroxides.
- Stepovik,Zaburdaeva,Dodonov
-
p. 264 - 269
(2007/10/03)
-
- Samarium(II) diiodide-mediated intermolecular aldol type reactions of phenacyl bromides with carbonyl compounds
-
Intermolecular aldol type reactions of phenacyl bromides with various carbonyl compounds mediated by samarium(II) diiodide afford β-hydroxy ketones in moderate to good yields.The addition of N,N,N',N'-tetramethylethylenediamine or diethylaluminium chlorid
- Aoyagi, Yutaka,Yoshimura, Mizue,Tsuda, Masako,Tsuchibuchi, Tomomasa,Kawamata, Saori,et al.
-
p. 689 - 692
(2007/10/02)
-
- Behavior and extension of the scope of NADH models to the reduction of non-activated ketones by a stable indolo NADH model compound in the presence of Lewis acids
-
The reduction of non-activated ketones, eg, acetophenone, by a very stable NADH model in the presence of Lewis acids (AlX3, Et2AlCl) is reported.During the reaction, a side equilibrated aldol condensation occurs.Due to the reversibility of this reaction, the overall yield in alcohol is not notably diminished.The scope of NADH models has been extended for the first time to non-activated ketones, such as dialkyl, aryl alkyl and diaryl ketones. - Keywords: NADH model / ketone reduction / Lewis acids / aldol condensation
- Berkous, Rabia,Dupas, Georges,Bourguignon, Jean,Queguiner, Guy
-
p. 632 - 635
(2007/10/02)
-
- New Effective Catalysts for Mukaiyama-Aldol and -Michael Reactions: BiCl3 - Metallic Iodide Systems
-
Metallic iodide-activated bismuth(III) chloride efficiently catalyzes the Mukaiyama-Aldol and -Michael reactions.Some examples of reactions of silyl enol ethers derived from acetophenone and cyclohexanone (1 and 2, respectively) with aldehydes, ketones, a
- Roux, Christophe Le,Gaspard-Iloughmane, Hafida,Dubac, Jacques,Jaud, Joel,Vignaux, Pierre
-
p. 1835 - 1839
(2007/10/02)
-
- Homogeneous catalysis. Transition metal based lewis acid catalysts
-
Transition metal based Lewis acids provide catalysts for the Diels-Alder and Mukaiyama reactions. These catalysts must possess an electron deficient axophilic metal center and a labile coordination position. Unlike traditional Lewis acids, those derived from transition metals can function in the presence of water and have well defined structures. It is shown how a normally electron rich ruthenium atom can be converted to a Lewis acid by incorporation of electron withdrawing ligands and ligands with hard donor atoms. This ruthenium complex, [Ru(salen)(NO)(H2O)]+, is an efficient catalyst for the Diels-Alder reaction, but in the Mukaiyama reaction, it tends to be reduced and thereby deactivated by the silyl enol ether. It is shown that the complex [TiCp*2(H2O)2]2+ (Cp* is pentamethylcyclopentadienyl) is an efficient catalyst for the Diels-Alder reaction even when water is present. Similarly, the triflato complexes [TiCp2(CF3 SO3)2] and [ZrCp2(CF3SO3)2] (Cp is cyclopentadienyl) are efficient catalysts for both the Diels-Alder and Mukaiyama reactions. All of these catalysts are effective at very low loadings of ≈ 1 mol%. Catalysis has been shown to occur via substrate-catalyst adducts and moreover these adducts are formed rapidly and reversibly as required for efficient catalysis.
- Hollis, T. Keith,Odenkirk, William,Robinson,Whelan, John,Bosnich
-
p. 5415 - 5430
(2007/10/02)
-
- Bismuth Trichloride as a New Efficient Catalyst in the Aldol Reaction and the Michael Reaction
-
In the presence of a catalytic amount of bismuth(III) trichloride (5 mol percent), silyl enol ethers react with aldehydes at room temperature in dichloromethane to give the corresponding aldols in good yields.Silyl enol ethers also have been found to reac
- Wada, Makoto,Takeichi, Eiji,Matsumoto, Takashi
-
p. 990 - 994
(2007/10/02)
-
- Exploratory Study on Photoinduced Single Electron Transfer Reactions of α,β-Epoxy Ketones with Amines
-
Photoinduced single electron transfer (SET) reactions of α,β-epoxy ketones have been studied using alkylamine electron donors.Irradiation of chalcone epoxide 1 with triethylamine (TEA) afforded β-diketone 2 and β-hydroxy ketne 3.Photoreaction of 1 with TEA in MeOH resulted in a slightly increased product ratio (3/2) compared with that in MeCN.When 1,4-diazabicyclooctane (DABCO) was used instead of TEA, a decrease in the yield of 3 was observed.Only 2 was obtained on irradiation of a solution of 1 in TEA and MeCN containing LiClO4.Studies of photoreactions of dypnone epoxide 9, benzoylisopropylethylene epoxide 12, and acrylophenone epoxide 15 indicate that the nature of β-substituent also influences the product distribution.It was also found that 1,6-bis(dimethylamino)pyrene (BDMAP) sensitizes the photoreaction of 1 in the presence of TEA to produce 2.Based on the results obtained, a reaction mechanism involving selective Cα-O bond cleavage of intermediate α,β-epoxy ketone anion radicals is proposed.
- Hasegawa, Eietsu,Ishiyama, Kenyuki,Horaguchi, Takaaki,Shimizu, Takahachi
-
p. 1631 - 1635
(2007/10/02)
-
- BISMUTH TRICHLORIDE AS A NEW EFFICIENT CATALYST IN THE ALDOL REACTION
-
In the presence of a catalytic amount of bismuth trichloride (5 molpercent), silyl enol ethers react with aldehydes at room temperature to give the corresponding aldols in good yields.
- Ohki, Hidenori,Wada, Makoto,Akiba, Kin-ya
-
p. 4719 - 4722
(2007/10/02)
-
- ENOLBORONATES: NEW PRACTICAL REAGENTS FOR REGIOSELECTIVE ALDOL CONDENSATIONS.
-
Enolboronates, new enolates directly accessible from carbonyl compounds and giving aldol products regioselectively and in good yield with aliphatic and aromatic aldehydes, are described.
- Gennari, Cesare,Colombo, Lino,Poli, Giovanni
-
p. 2279 - 2282
(2007/10/02)
-
- SYNTHESIS AND DECOMPOSITION OF E- AND Z-3,3,5-TRISUBSTITUTED 1,2-DIOXOLANES.
-
The reactions of a number of ozonides and olefins in the presence of boron trifluoride-diethyl ether gave the corresponding mixtures of (E)- and (Z)-1,2-dioxolanes in 12-70% yield. The decomposition of the E-Z isomeric 1,2-dioxolanes 3a-c was undertaken under a variety of conditions, i. e. , thermal, TiCl//4-mediated, FeSO//4-catalyzed, and LiAlH//4-mediated decompositions.
- Yoshida,Miura,Nojima,Kusabayashi
-
p. 6279 - 6285
(2007/10/02)
-