- Evaluation of the Pharmacophoric Role of the O-O Bond in Synthetic Antileishmanial Compounds: Comparison between 1,2-Dioxanes and Tetrahydropyrans
-
Leishmaniases are neglected diseases that can be treated with a limited drug arsenal; the development of new molecules is therefore a priority. Recent evidence indicates that endoperoxides, including artemisinin and its derivatives, possess antileishmanial activity. Here, 1,2-dioxanes were synthesized with their corresponding tetrahydropyrans lacking the peroxide bridge, to ascertain if this group is a key pharmacophoric requirement for the antileishmanial bioactivity. Newly synthesized compounds were examined in vitro, and their mechanism of action was preliminarily investigated. Three endoperoxides and their corresponding tetrahydropyrans effectively inhibited the growth of Leishmania donovani promastigotes and amastigotes, and iron did not play a significant role in their activation. Further, reactive oxygen species were produced in both endoperoxide-and tetrahydropyran-Treated promastigotes. In conclusion, the peroxide group proved not to be crucial for the antileishmanial bioactivity of endoperoxides, under the tested conditions. Our findings reveal the potential of both 1,2-dioxanes and tetrahydropyrans as lead compounds for novel therapies against Leishmania.
- Ortalli, Margherita,Varani, Stefania,Cimato, Giorgia,Veronesi, Ruben,Quintavalla, Arianna,Lombardo, Marco,Monari, Magda,Trombini, Claudio
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p. 13140 - 13158
(2020/11/13)
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- Graphene-catalyzed transacetalization under acid-free conditions
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1,2- and 1,3-Diols are readily protected as cyclic acetals and ketals through a graphene-catalyzed transacetalization process. The methodology features an atom economic procedure since quasi-stoichiometric conditions have been developed. Unlike prior systems, the graphene-catalyzed transacetalization is performed under Br?nsted and Lewis acid-free conditions and without solvent. Our method has been applied to several volatile compounds that are unsuitable for complex work-up and extensive purification steps. The very unusual catalytic properties of graphene for transacetalization reactions are ascribed to molecular charge transfer between graphene and substrates.
- Nongbe, Medy C.,Oger, Nicolas,Ekou, Tchirioua,Ekou, Lynda,Yao, Benjamin K.,Le Grognec, Erwan,Felpin, Fran?ois-Xavier
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p. 4637 - 4639
(2016/09/23)
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- Phosphorus promoted SO42-/TiO2 solid acid catalyst for acetalization reaction
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A novel phosphorus modifed SO42-/TiO2 catalyst was synthesized by a facile coprecipitation method, followed by calcination. The catalytic performance of this novel solid acid was evaluated by acetalization. The results showed that the phosphorus was very effcient to enhance the catalytic activity of SO42-/TiO2. The solid acid owned high activity for the acetalization with the yields over 90%. Moreover, the solid acid could be reused for six times without loss of initial catalytic activities.
- Zhong, Shaofeng,Ou, Qiongrong,Shao, Linjun
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p. 3005 - 3008
(2015/11/27)
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- Rapid assessment of protecting-group stability by using a robustness screen
-
An experimentally simple method has been developed to rapidly establish the stability of widely utilized silyl, acetal, and carbamate protecting groups to a given set of reaction conditions. Assessment of up to twelve protecting groups in a single experiment has been demonstrated. Evaluation of this protocol in two unrelated synthetic transformations suggests that this method can be used to select appropriate protecting groups in the design of synthetic routes.
- Collins, Karl D.,Ruehling, Andreas,Lied, Fabian,Glorius, Frank
-
supporting information
p. 3800 - 3805
(2014/04/03)
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- Four acid-catalysed dehydration reactions proceed without interference
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Four acid-catalysed dehydration reactions can proceed in one pot, simultaneously and without interference, to yield one imine, one acetal (or boronic ester), one ester and one alkene, even though many other cross-products could be conceived. This advanced
- Lirag, Rio Carlo,Miljani?, Ognjen ?.
-
supporting information
p. 9401 - 9404
(2014/08/05)
-
- Facile aldolization catalyzed by ionic liquid [4-sulfbmpyrazine][BF 4]
-
The acidic functionalized ionic liquid 1-(4-sulfonic group)butyl-3- methylpyrazine tetrafluoroborate (abbreviated as [4-sulfbmpyrazine][BF 4]) was employed as the catalyst of the condensation of aromatic aldehyde and diols. The optimized condition was as follows: aromatic aldehyde (0.20 mol), diols (0.30 mol) and [4-sulfbmpyrazine][BF4] (0.60 g) were refluxed in cyclohexane (10.00 mL) for 1 h. A series of aromatic aldehydes were studied and afforded the corresponding acetals products with good yields which were from 70.3 to 96.9 %. The ionic liquid catalyst could be recycled for four times without significant loss of catalyst reactivity.
- Zou, Jianzhong,Yi, Fengping,Zhang, Lirong,Wang, Zhen
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p. 6643 - 6646
(2013/07/26)
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- Synthesis of a novel melamine-formaldehyde resin-supported ionic liquid with Bronsted acid sites and its catalytic activities
-
Bronsted acidic ionic liquid immobilized on a melamine-formaldehyde resin (AIL-MFR) was synthesized through the reaction of melamine-formaldehyde resin (MFR) with 1,4-butanesulfonate. Using PEG-2000 as the additive, the MFR can be prepared in regular microspheres with an average diameter of 3.97 μm and surface area of 9.09 m2 g-1. The AIL-MFR had high acidity of 2.93 mmol g-1, mainly from the sulfonic groups. The catalysis results showed that the AIL-MFR had high activity and stability for acetalization with excellent conversions and yields for most substrates. Furthermore, immobilization of the acidic ionic liquid on the MFR made the recycling of the catalyst convenient.
- Xing, Guiying
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p. 1369 - 1374
(2013/10/01)
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- Synthesis of novel solid acidic ionic liquid polymer and its catalytic activities
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The novel solid acidic ionic liquid polymer has been synthesized through the copolymerization of acidic ionic liquid oligomers and resorcinol- formaldehyde (RF resin). The catalytic activities were investigated through the acetalization. The results showed that the PIL was very efficient for the reactions with the average yield over 99.0%. The procedure was quite simple with just one-step to complete both the reactions. The high hydrophobic BET surface, high catalytic activities and high stability gave the PIL great potential for green chemical processes. Pleiades Publishing, Ltd., 2013.
- Liang, Xuezheng
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p. 724 - 729
(2014/01/23)
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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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experimental part
p. 7775 - 7781
(2012/09/21)
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- Polyacrylonitrile fiber mat supported solid acid catalyst for acetalization
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A novel polyacrylonitrile hybrid fiber mat supported solid acid catalyst was prepared by electrospin-ning, and its catalytic activities were carefully investigated through acetalization reactions. The results showed that this hybrid fiber mat exhibits high activity for the reactions, with average yields over 95%. Besides having catalytic activities similar to the solid acid, the heterogeneous solid acid/polyacrylonitrile mat can be reused in six runs without significant loss of catalytic activities. The large size of the hybrid fiber mat greatly facilitates recovery of the catalyst from the reaction mixture. The high and stable catalytic activities of the hybrid fiber mat hold great potential for green chemical processes and preparation of membrane reactors in the future.
- Shao, Linjun,Du, Yijun,Xing, Guiying,Lv, Weixi,Liang, Xuezheng,Qi, Chenze
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experimental part
p. 1199 - 1203
(2012/10/07)
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- Efficient and chemoselective acetalization and thioacetalization of carbonyls and subsequent deprotection using InF3 as a reusable catalyst
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An efficient and chemoselective method for preparation of acetals and dithioacetals of aldehydes and their deprotection under catalysis of InF 3 is described.
- Madabhushi, Sridhar,Mallu, Kishore Kumar Reddy,Chinthala, Narsaiah,Beeram, China Ramanaiah,Vangipuram, Venkata Sairam
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experimental part
p. 697 - 701
(2012/02/15)
-
- Catalytic enantioselective conjugate allylation of unsaturated methylidene ketones
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The use of unsaturated methylidene ketones in catalytic conjugate allylations allows a significant expansion in substrate scope and, with appropriate chiral ligands, occurs in a highly enantioselective fashion.(Figure Presented)
- Brozek, Laura A.,Sieber, Joshua D.,Morken, James P.
-
supporting information; scheme or table
p. 995 - 997
(2011/05/15)
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- Indium triflate mediated tandem acetalisation-acetal exchange reactions under solvent-free conditions
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Acyclic acetals and ketals undergo exchange reactions in the presence of catalytic quantities of indium(III) triflate and diols to generate the corresponding cyclic acetals and ketals in excellent yield. The protocol is rapid, employs mild conditions and can be adapted to employ solvent-free reaction conditions. We have further developed this methodology to encompass a tandem acetalisation-acetal exchange protocol which provides facile access to cyclic ketals from unreactive ketones also under very mild, solvent-free reaction conditions.
- Smith, Brendan M.,Graham, Andrew E.
-
experimental part
p. 6281 - 6283
(2011/12/14)
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- Acetalization of carbonyl compounds catalyzed by acidic ionic liquid immobilized on silica gel
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Imidazolium-silica heterogeneous catalyst (SG-[(CH2) 3SO3H-HIM]HSO4) was prepared by immobilization of acidic ionic liquid 1-(propyl-3-sulfonate) imidazolium hydrosulfate ([(CH2)3SO3H-HIM]HSO4) on silica-gel using tetraethoxysilane (TEOS) as silica source in this study. The properties of the samples were characterized by FT-IR, SEM and TG/DSC. The results suggested that [(CH2)3SO3H-HIM]HSO4 had been successfully immobilized on the surface of silica-gel and the immobilized ionic liquid catalyst SG-[(CH2)3SO 3H-HIM]HSO4 had good thermal stability. The original smooth surface of silica-gel was covered with [(CH2) 3SO3H-HIM]HSO4 and a rough surface of SG-[(CH2)3SO3H-HIM]HSO4 was formed, but the size of particles had no obvious change. Moreover, SG-[(CH 2)3SO3H-HIM]HSO4 exhibited high catalytic activity for a series of acetalization and could be recovered easily. After reused for 10 times in the synthesis of benzaldehyde ethanediol acetal, the catalyst could still give satisfactory catalytic activity.
- Miao, Jinmei,Wan, Hui,Shao, Yanbing,Guan, Guofeng,Xu, Bin
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experimental part
p. 77 - 82
(2011/11/07)
-
- Synthesis of a novel ionic liquid with both Lewis and Br?nsted acid sites and its catalytic activities
-
The novel ionic liquid with both Lewis and Br?nsted acid sites has been synthesized and its catalytic activities for acetalization and Michael addition were investigated carefully. The novel ionic liquid was stable to water and could be used in aqueous solution. Furthermore, the molar ratio of the Lewis and Br?nsted acid sites could be adjusted according to different reactions. The results showed that the novel ionic liquid was very efficient for the traditional acid-catalyzed reactions with good to excellent yields in short time.
- Liang, Xuezheng,Qi, Chenze
-
experimental part
p. 808 - 812
(2012/01/04)
-
- Chemoselective and chemospecific protection and deprotection of a carbonyl group using polystyrene divinylbenzene sulfonic acid
-
Chemospecific protection of one carbonyl group of two identical carbonyls of 2,2-dialkyl-1,3-cyclohexanedione and chemoselective protection of aliphatic or aromatic carbonyls in the presence of conjugated carbonyl compounds using cross-linked polystyrene divinyl benzene sulfonic acid (SPS) as a heterogeneous catalyst has been demonstrated. Copyright
- Verma, Sanjeev K.,Sathe, Manisha,Kaushik
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experimental part
p. 1701 - 1707
(2010/07/15)
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- Indium(III)trifluoromethanesulfonate as a mild, efficient catalyst for the formation of acetals and ketals in the presence of acid sensitive functional groups
-
Aldehydes and ketones, including acetophenone and benzophenone, are readily protected under mild, neutral conditions in the presence of various alcohols or orthoformates and catalytic amounts of indium(III) trifluoromethanesulfonate (0.8 mol %) under either room temperature or mild heating conditions to give the corresponding cyclic and acyclic acetals and ketals in good to excellent yields. Acid sensitive functional groups, N-Boc, THP, and TBDMS do not undergo competitive deprotection under the reported conditions.
- Gregg, Brian T.,Golden, Kathryn C.,Quinn, John F.
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p. 3287 - 3295
(2008/09/21)
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- 3,3,9,9-Tetramethyl-1,5,7,11-tetraoxaspiro[5.5]undecane as a reagent for protection of carbonyl compounds
-
3,3,9,9-Tetramethyl-1,5,7,11-tetraoxaspiro[5.5]undecane is introduced as a new, stable and chemoselective reagent for the protection of aldehydes and ketones under mild reaction condition in high yield.
- Rahimizadeh, Mohammad,Bakavoli, Mehdi,Shiri, Ali,Eshghi, Hossein,Saberi, Sattar
-
experimental part
p. 704 - 706
(2009/09/25)
-
- Sequential and tandem oxidation/acetalization procedures for the direct generation of acetals from alcohols
-
Alcohols are transformed directly into either acyclic or cyclic acetals in both tandem and sequential oxidation/acetalization processes using manganese dioxide, trialkyl orthoformates and catalytic quantities of indium triflate.
- Smith, Brendan M.,Graham, Andrew E.
-
p. 4891 - 4894
(2008/02/08)
-
- Approaches to the synthesis of enantiopure α-hydroxy-β-lactams with functionalized side chains
-
We report a synthesis of pharmaceutically important α-hydroxy (or t-butyldimethylsilyl protected α-hydroxy)-β-lactams with functionalized chains in position 4 of the azetidinone ring. A convenient and high-yielding route to these compounds was developed and optimized. Preparation and characterization of several new enantiopure title compounds with various functional groups are discussed.
- Yang, Yan,Wang, Jianmei,Kayser, Margaret
-
p. 2021 - 2029
(2008/02/11)
-
- Mesoporous aluminosilicate promoted protection and deprotection of carbonyl compounds
-
Mesoporous aluminosilicates are efficient heterogeneous catalysts for both the formation and hydrolysis of a range of acetals under mild conditions and in short reaction times.
- Robinson, Mathew W.C.,Graham, Andrew E.
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p. 4727 - 4731
(2008/02/07)
-
- Indium triflate mediated acetalization of aldehydes and ketones
-
Aldehydes and ketones are rapidly transformed into either acyclic or cyclic acetals at room temperature in high yields and in very short reaction times using catalytic quantities of indium triflate, in contrast to previous reports.
- Smith, Brendan M.,Graham, Andrew E.
-
p. 9317 - 9319
(2007/10/03)
-
- Chemoselective conversion of aromatic epoxide and 1,2-diol to 1,3-dioxane derivatives with phenyltrimethylammonium tribromide in the presence of a catalytic amount of antimony(III) bromide
-
trans-Stilbene oxide was oxidatively converted to 2-phenyl-1,3-dioxanes with phenyltrimethylammonium tribromide in the presence of various 1,3-diols and a catalytic amount of SbBr3 in DMSO at room temperature. Aromatic 1,2-diol, such as hydrobenzoin, was similarly converted to 2-aryl-1,3-dioxane derivatives under the same reaction conditions.
- Sayama, Shinsei
-
p. 4001 - 4005
(2007/10/03)
-
- An efficient procedure for protection of carbonyls in Br?nsted acidic ionic liquid [Hmim]BF4
-
Protection of carbonyls as acetals or ketals using Br?nsted acidic ionic liquid [Hmim]BF4 as catalyst as well as solvent was investigated. Satisfactory results were obtained for the protection of carbonyls as cycloacetals or ketals with diols. The product can be separated conveniently from the reaction system, and the ionic liquid can be reused after removal of water.
- Wu, Hai-Hong,Yang, Fan,Cui, Peng,Tang, Jie,He, Ming-Yuan
-
p. 4963 - 4965
(2007/10/03)
-
- Enantioselective total synthesis of epothilones A and B using multifunctional asymmetric catalysis
-
An enantioselective total synthesis of epothilones A (1) and B (2) using multifunctional asymmetric catalysis such as a cyanosilylation of an aldehyde, an aldol reaction of an unmodified ketone with an aldehyde, and a protonation in the conjugate addition of a thiol to an α,β-unsaturated thioester has been achieved. We divided 1 and 2 into fragment A, fragment B, and fragment C. A catalytic asymmetric synthesis of fragments A and B was accomplished using a catalytic asymmetric cyanosilylation as a key step. An enantiocontrolled synthesis of fragment C was achieved in two ways. One is the use of a direct catalytic asymmetric aldol reaction of an unmodified ketone with an aldehyde as a key step, and the other utilizes a catalytic asymmetric protonation in the conjugate addition of a thiol to an α,β-unsaturated thioester as a key step. Suzuki cross-coupling of fragment A with fragment C followed by Yamaguchi lactonization as key steps led to an enantiocontrolled synthesis of epothilone A (1). On the other hand, Suzuki cross-coupling of fragment B with fragment C followed by Yamaguchi lactonization accomplished an enantiocontrolled synthesis of epothilone B (2).
- Sawada, Daisuke,Kanai, Motomu,Shibasaki, Masakatsu
-
p. 10521 - 10532
(2007/10/03)
-
- Solid supported reactions and reagents XIV [1]: Envirocat EPZG as a novel catalyst for selective acetalization of aldehydes and ketones
-
Envirocat EPZG is an efficient reusable catalyst for acetalization of aldehydes and ketones. The isolation of pure products in high yields by simple filtration and evaporation of the solvent is an important feature of this method.
- Bandgar, Babasaheb P.,Gaikwad, Nandkumar B.
-
p. 719 - 722
(2007/10/03)
-
- Efficient Synthesis of Acetals Promoted by a Yttria-Zirconia Based Strong Lewis Acid Catalyst
-
A variety of carbonyl compounds react with 2,2-dimethylpropane-1,3-diol in the presence of a catalytic amount of a novel yttria-zirconia based strong Lewis acid to afford the corresponding acetals in excellent yields.
- Pals, Godwin C. G.,Keshavaraja,Saravanan,Kumar, Pradeep
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p. 426 - 427
(2007/10/03)
-
- A Novel Approach to the Synthesis of Taxol. A Synthesis of Optically Active 3,7-dibenzyloxy-4,8-di-t-butyl-dimethylsiloxy-5,5-dimethyl-6-p-methoxybenzyloxy-2-octanone by Way of Stereoselective Aldol Reactions
-
Optically active 3,7-dibenzyloxy-4,8-di-t-butyldimethylsiloxy-5,5-dimethyl-6-p-methoxybenzyloxy-2-octanone (2) has been synthesized by way of diastereoselective aldol reaction between 4-benzyloxy-5-t-butyldimethylsiloxy-2,2-dimethyl-3-p-methoxy-benzyloxypentanal (3) and ketene silyl acetal 4 using MgBr2*OEt2 as a catalyst.The chiral pentanal 3 was synthesized either by asymmetric aldol reaction of both prochiral aldehyde 5 and ketene silyl acetal 4 using a chiral Lewis acid or by diastereoselective aldol reaction between the chiral aldehyde 6 derived from L-serine andthe lithium enolate derived from methyl isobutyrate.
- Mukaiyama, Teruaki,Shiina, Isamu,Sakata, Kaku,Emura, Takayuki,Seto, Keitarou,Saitoh, Masahiro
-
p. 179 - 180
(2007/10/02)
-
- Geminal Substituent Effects. VIII. Enthalpies of Formation od Acetals
-
The standard enthalpies of combustion ΔHoc(1 or c) of the α-phenyl-substituted acetals (1) and diacetals (2) were measured calorimetrically.The enthalpies of vaporisation or sublimation ΔHvap or ΔHsub of 1-2 were obtained from the temperature function of the vapor pressure measured in a flow system, and the standard enthalpies of formation are obtained thereof: ΔH0f (l or c) and ΔHof (g) (in kJ mol-1 for 1a= -308.40+/-0.52(1), -248.94+/-0.88; 1b= -343.48+/-0.72(1), -288.5+/-1.5; 1c= -267.4+/-1.3(1), -205.3+/-1.3; 1d = -343.8+/-2.1 (c), -261.9+/-2.2; 1e = -397.02+/-0.86 ( c), -311.3+/-1.2; 1f = -414.52+/-0.80 (1), -350.68+/-0.86; 2a = -564.8+/-2.4 (c), -467.1+/-2.5; 2b = -547.6+/-1.6 (c), -414.9+/-2.7; 2c = -717.1+/-7.5 (c), -587.0+/-8.0.The results are combined into values of two strain free group increments CHPh> = -59.7 and CPh, C> = -71.3 kJ mol-1; and compared to the aliphatic series of acetals.
- Verevkin, Sergey P.,Dogan, Barbara,Haedrich, Johannes,Beckhaus, Hans-Dieter,Ruechardt, Christoph
-
-
- N-(arylmethyl)-2-(or -4)-cyanopyridinium hexafluoroantimonates as new useful catalysts for acetalization of carbonyl compounds
-
Carbonyl compounds 1 were converted to the corresponding 1,3-dioxolanes 2 and 1,3-dioxanes 4 with ethylene glycol and 2,2-dimethyl-1,3-propandiol, respectively, in the presence of 1-3 mol% of N-(benzyl, 4-methylbenzyl or 4-methoxybenzyl)-2(or -4)cyanopyridinium hexafluoroantimonates 3. The catalyst 3d was also effective for the tetrahydropyranylation.
- Lee,Lee,Takata,Endo
-
p. 368 - 370
(2007/10/02)
-
- Synthesis of Bryostatins. 1. Construction of the C(1)-C(16) Fragment
-
The synthesis of fragment AB of bryostatin 1 is described.Two aldol coupling reactions involving (i) chiral fragment A with achiral B and (ii) chiral fragment A1 with achiral A2 constitute crucial steps in which an external chiral boron reagent is used to control stereoselectivity in the creation of a new stereogenic center.This type of double asymmetric synthesis, although rarely precedented, provides a powerful means of stereocontrol over the fragment assembly.
- Blanchette, Mary A.,Malamas, Michael S.,Nantz, Michael H.,Roberts, John C.,Somfai, Peter,et al.
-
p. 2817 - 2825
(2007/10/02)
-
- A FACILE CLEAVAGE OF BENZYLIDENE ACETALS WITH DIISOBUTYLALUMINUM HYDRIDE
-
Benzylidene acetals of 1,2- and 1,3-glycols are easily cleft by diisobutylaluminum hydride in a toluene solution at 0 deg C - room temperature to give the corresponding monobenzyl ethers of the glycols.In general the reaction proceeds excellently in regioselective manner depending on the stereochemical environment.
- Takano, Seiichi,Akiyama, Masashi,Sato, Seiji,Ogasawara, Kunio
-
p. 1593 - 1596
(2007/10/02)
-
- REACTION OF CYCLIC ACETALS WITH 1,3-DIOXANIUM SALTS
-
The products from reaction of 1,3-dioxacycloalkanes with 1,3-dioxanium tetrafluoroborates are a new pair of compounds, i.e., 1,3-dioxacycloalkanium tetrafluoroborate and 1,3-dioxane.The reaction is reversible and takes place by a transacetalization mechanism.
- Chalova, O. B.,Kurmaeva, E. S.,Kantor, E. A.,Kiladze, T. K.,Rakhmankulov, D. L.
-
p. 1434 - 1437
(2007/10/02)
-
- Aldehydes, tert. Amines or Acetales from Amidacetales and Grignard-Compounds
-
Amidacetales 1 or -mercaptales 9 respectively react with Grignard-agents dependent on molar ratio by exchange of methoxy- or methylthio group via not isolable O,N- or S,N-acetales to the corresponding aldehydes 4 or the tert. amines 3.Starting from bicyclic amidacetales 6 aldehydes or bis-β-hydroxyethylamines 8 are formed.By quarternisation of the amidacetal-nitrogen followed by reaction with Grignard-agents the corresponding O,O-acetales are formed.
- Walther, H.,Haase, L.,Gross, H.,Costisella, B.,Keitel, I.
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p. 902 - 908
(2007/10/02)
-