- Divergent Rearrangements of Vinylcyclopropane into Skipped Diene and Cyclopentene: Mechanism, Scope, and Limitations
-
Vinylcyclopropanes are versatile intermediates in organic synthesis which undergo various rearrangements. We report a new rearrangement of vinylcyclopropane into skipped diene. A detailed mechanistic study revealed that this transformation involves regioselective ring-opening of the cyclopropane ring followed by 1,2-migration of one of the cyclopropane substituents. Interestingly, our investigations showed that skipped diene is the kinetic product of the process but formation of a more stable cyclopentene is also accessible. The fundamental understanding of the processes involved enabled the development of divergent methodologies allowing to obtain cyclopentene or skipped diene from vinylcyclopropane in a selective and controlled manner.
- Delbrassinne, Arnaud,Richald, Maximilien,Janssens, Julien,Robiette, Rapha?l
-
supporting information
p. 2862 - 2868
(2021/06/11)
-
- Ball-Milling-Enabled Reactivity of Manganese Metal**
-
Efforts to generate organomanganese reagents under ball-milling conditions have led to the serendipitous discovery that manganese metal can mediate the reductive dimerization of arylidene malonates. The newly uncovered process has been optimized and its mechanism explored using CV measurements, radical trapping experiments, EPR spectroscopy, and solution control reactions. This unique reactivity can also be translated to solution whereupon pre-milling of the manganese is required.
- Bolt, Robert R. A.,Browne, Duncan L.,Howard, Joseph L.,Khan, Adam,Magri, Giuseppina,Morrill, Louis C.,Nicholson, William I.,Richards, Emma,Seastram, Alex C.
-
supporting information
p. 23128 - 23133
(2021/09/20)
-
- Protic Ionic Liquid as Reagent, Catalyst, and Solvent: 1-Methylimidazolium Thiocyanate
-
We propose a new concept of the triple role of protic ionic liquids with nucleophilic anions: a) a regenerable solvent, b) a Br?nsted acid inducing diverse transformations via general acid catalysis, and c) a source of a nucleophile. The efficiency of this strategy was demonstrated using thiocyanate-based protic ionic liquids for the ring-opening of donor-acceptor cyclopropanes. A wide variety of activated cyclopropanes were found to react with 1-methylimidazolium thiocyanate under mild metal-free conditions via unusual nitrogen attack of the ambident thiocyanate ion on the electrophilic center of the three-membered ring affording pyrrolidine-2-thiones bearing donor and acceptor substituents at the C(5) and C(3) atoms, respectively, in a single time-efficient step. The ability of 1-methylimidazolium thiocyanate to serve as a triplex reagent was exemplarily illustrated by (4+2)-annulation with 1-acyl-2-(2-hydroxyphenyl)cyclopropane, epoxide ring-opening and other organic transformations.
- Andreev, Ivan A.,Ratmanova, Nina K.,Augustin, André U.,Ivanova, Olga A.,Levina, Irina I.,Khrustalev, Victor N.,Werz, Daniel B.,Trushkov, Igor V.
-
supporting information
p. 7927 - 7934
(2021/03/03)
-
- A facile, efficient and solvent-free titanium (IV) ethoxide catalysed knoevenagel condensation of aldehydes and active methylenes
-
Titanium ethoxide has been employed as a novel and efficient reagent for the Knoevenagel condensation of aldehydes with active methylenes such as diethyl malonate and ethyl cyanoacetate under solvent free conditions to afford substituted olefins in high to excellent yields. The reaction is suitable for a variety of aromatic, aliphatic and heteroaromatic aldehydes with various active methylenes. Parallel to this, microwave irradiation has been utilized to achieve improved reaction rates and enhanced yields. Herein, we illustrated a convenient method for the preparation of α,β-unsaturated compounds using both conventional and microwave irradiation methods. An efficient and solvent free Knoevenagel condensation between aldehydes and active methylenes was developed using titanium ethoxide. The procedure proved to be successful with a wide range of substrates such as aromatic, aliphatic and heterocyclic aldehydes and various active methylenes to afford substituted olefins. The reaction was also carried out under microwave irradiation to accomplish the corresponding olefins with improved reaction rates, yields and cleaner reaction profiles.We have developed an efficient and novel methodology for the synthesis of olefinic compounds by Knoevenagel condensation under solvent-free conditions using titanium ethoxide, for the first time, as a reagent as well as a solvent. This method is appropriate for the synthesis of a variety of aromatic aldehydes containing various electron-donating and withdrawing groups, aliphatic and heteroaromatic aldehydes. The significant advantages offered by this methodology could be applied to various active methylenes in order to offer the corresponding Knoevenagel products. Thus, we believe that this method delivers high conversions, cleaner reaction profiles under solvent-free reaction conditions and shorter reaction times, all of which make it a very useful and attractive approach for the preparation of a wide range of substituted olefins.
- Ramaiah, Manjunatha M.,Shivananju, Nanjunda Swamy,Shubha, Priya Babu
-
p. 107 - 115
(2020/02/04)
-
- Co-Polymeric Nanosponges from Cellulose Biomass as Heterogeneous Catalysts for amine-catalyzed Organic Reactions
-
Heterogeneous catalysts prepared from biomass waste sources are attracting increasing interest. The reasons rely on the possibility of combining the virtuous approach of circular economy with the consolidated advantages of heterogeneous catalysis, namely the recycling of the system and the possibility to drive selectivity towards desired products. Herein we report a highly porous cellulose-based nanosponge (CNS) and its use as a recoverable catalyst for Henry and Knoevenagel reactions, two classical amino-catalyzed transformations. The material is obtained by cross-linking between TEMPO-oxidized cellulose nanofibers (TOCNF) and branched polyethyleneimine 25 kDa (bPEI) in the presence of citric acid. CNS have been developed as sorbent materials for water remediation but their use as heterogeneous catalysts was never investigated. The fully characterized micro- and nano-porous system guarantees a complete penetration of CNS, allowing reagents to diffuse within. Indeed, by modulating reaction conditions (catalyst loading, temperature, solvent, microwave versus conventional heating, relative ratio of reagents) it was possible to drive selectivity towards the desired products, while maintaining high efficiency in terms of conversion. The catalyst could be re-used several times without losing in catalytic efficiency. In most cases the products’ distribution is quite different from homogeneous conditions, this much more emphasizing the importance of this heterogeneous solution.
- Riva, Laura,Punta, Carlo,Sacchetti, Alessandro
-
p. 6214 - 6222
(2020/10/02)
-
- Programmed Sequential Additions to Halogenated Mucononitriles
-
Dihalomucononitriles were synthesized and their reactivity evaluated to assess their ability to function as linchpin reagents. Bis(2-chloroacrylonitrile) and bis(2-bromoacrylonitrile) were synthesized from 2,1,3-benzothiadiazole and undergo conjugate addition/elimination reactions with both nitrogen (40-95% yield) and carbon nucleophiles (72-93% yield). Secondary amines undergo monosubstitutions, while carbon nucleophiles are added twice. The sequence of addition of the nucleophiles could be controlled to give mixed addition products. The multicomponent coupling products could then be converted to natural product like motifs using intramolecular cyclization reactions.
- Zahara, Adam J.,Hinds, Elsa M.,Nguyen, Andrew L.,Wilkerson-Hill, Sidney M.
-
supporting information
p. 8065 - 8069
(2020/11/02)
-
- Solvent-Free FeCl3-Assisted Electrophilic Fluorine-Catalyzed Knoevenagel Condensation to Yield α,β-Unsaturated Dicarbonyl Compounds and Coumarins
-
A highly environmentally friendly procedure was developed for the Knoevenagel condensation of aromatic aldehydes with diethyl malonate in the presence of FeCl3 and N-fluorobenzenesulfonimide as a source of electrophilic fluorine under solvent-free conditions. The scope of the reaction was explored using commercially available substrates. The reaction with substituted salicylaldehydes afforded the corresponding coumarin derivatives which attract interest due to their potential medicinal importance.
- Yang, Lu,Zhu, Jiang,Xie, Fukai,Peng, Xiaoshi,Lin, Bin,Liu, Yongxiang,Cheng, Maosheng
-
p. 1053 - 1060
(2019/09/06)
-
- [3+2] cycloadditions: Part XXXIV: Further investigations of cycloadditions of C,N-diaryl- and C-aryl-N-methyl nitrones to α,β-unsaturated esters
-
Investigations of [3+2] cycloadditions of C,N-diaryl and C-aryl-N-methyl nitrones as three atom components (TAC) to substituted methyl E-cinnamates and diethyl arylidene malonates have been further investigated. [3+2] Cycloadditions of cinnamates yielded mixtures of cycloadducts, the major products being the 3,4-trans-4,5-trans-2,3,5-triaryl-4-carbomethoxy products originating from the endo-carbonyl-exo-aryl meta channel approach of the cinnamate component. [3+2] Cycloadditions to diethyl arylidene malonates furnished single cycloadducts-3,5-trans-2-methyl-3,5-diaryl-4,4-dicarbethoxy isoxazolidines by a endo-aryl meta channel approach of the 2π-component.
- Sengupta, Sumana,Banerji, Avijit
-
p. 2777 - 2784
(2019/11/21)
-
- Metal free biomimetic deaminative direct C-C coupling of unprotected primary amines with active methylene compounds
-
An unprecedented direct C-C coupling reaction of unprotected primary amines with active methylene compounds is reported. The reaction involves a biomimetic deamination of amines which was achieved under conditions free of metallic reagents and strong oxidizing agents. A wide range of primary amines was reacted with different active methylene compounds to provide structurally diverse trisubstituted alkenes and dihydropyridines. A kinetic study revealed an activation barrier of 10.1 kcal mol-1 for the conversion of a key intermediate of the reaction.
- Ghosh, Santanu,Jana, Chandan K.
-
supporting information
p. 10153 - 10157
(2019/12/26)
-
- Highly Chemo- and Diastereoselective Dearomative [3 + 2] Cycloaddition Reactions of Benzazoles with Donor-Acceptor Oxiranes
-
A Sc(OTf)3-catalyzed dearomative [3 + 2] cycloaddition of benzazoles with donor-acceptor oxiranes through chemoselective C-C bond cleavage of oxiranes was developed under mild conditions. This reaction provides an efficient method to construct benzazolo[3,2-c]oxazole compounds in good yields and with high diastereoselectivity. The reaction has a general substrate scope, and the donor-acceptor oxiranes with electron-donating and electron-withdrawing groups on the aromatic ring afforded the desired cycloadducts.
- Zhang, Shan-Shan,Wang, Dong-Chao,Xie, Ming-Sheng,Qu, Gui-Rong,Guo, Hai-Ming
-
supporting information
p. 8026 - 8029
(2019/01/14)
-
- Decarboxylative Giese-Type Reaction of Carboxylic Acids Promoted by Visible Light: A Sustainable and Photoredox-Neutral Protocol
-
We describe herein a transition-metal-free method for the decarboxylative generation of radicals from carboxylic acids and their 1,4-addition to Michael acceptors. The Fukuzumi catalyst (9-mesitylene-10-methylacridinium perchlorate, [Acr-Mes]ClO4) enabled this transformation under visible-light irradiation at room temperature with CO2 as the only byproduct. The scope and limitations of this protocol were examined by using a range of Michael acceptors (15 examples) and carboxylic acids (18 examples). The use of 3-hydroxypivalic acid in this protocol allowed the straightforward formation of a diastereomerically pure δ-lactone. Moreover, when a homoallylic acid was used, a radical cascade reaction took place with the formation of three C–C bonds.
- Ramirez, Nieves P.,Gonzalez-Gomez, Jose C.
-
supporting information
p. 2154 - 2163
(2017/04/24)
-
- Synthesis of monosubstituted 1,1-dicarbonyl ester 1,3-dienes
-
The synthesis of various electron-deficient 1,1-dicarbonyl ester 1,3-dienes substituted in position 2 or 3 of the diene moiety has been developed. Georg Thieme Verlag Stuttgart. New York.
- Rousseau, Olivier,Delaunay, Thierry,Robiette, Rapha?l
-
supporting information
p. 519 - 522
(2014/03/21)
-
- Knoevenagel condensation of diethylmalonate with aldehydes catalyzed by immobilized bovine serum albumin (BSA)
-
Knoevenagel condensation between aldehydes and diethylmalonate is catalyzed efficiently by bovine serum albumin (BSA) immobilized covalently on an epoxy-functionalized polymeric support, Immobead IB-350. The reaction is carried out conveniently at room temperature in DMSO in which aliphatic, heterocyclic and aromatic aldehydes react efficiently. After extraction with heptane and treatment with Candida antarctica lipase CAL B, the products are obtained in >95% purity and 85-89% yield. The solvent DMSO, unreacted diethylmalonate and immobilized BSA were easily recovered. Immobilized BSA and recovered DMSO were recycled 5 times without any appreciable loss in yield.
- Ramesh, Perla,Shalini, Basetty,Fadnavis, Nitin W.
-
p. 7368 - 7373
(2014/02/14)
-
- Design and synthesis of 6-oxo-1,4,5,6-tetrahydropyrimidine-5-carboxylate derivatives as neuraminidase inhibitors
-
A series of 6-oxo-1,4,5,6-tetrahydropyrimidine-5-carboxylate derivatives were prepared to evaluate their ability of inhibiting neuraminidase (NA) of influenza A virus. All the compounds were synthesized in good yields starting from aldehyde by using a suitable synthetic strategy, which showed moderate inhibitory activity against influenza A NA. Compound 6g exhibited the strongest inhibitory activity against influenza virus A NA (IC50 = 17.64 μM), which indicated pyrimidine ring could be used as a core structure to design novel influenza NA inhibitors.
- Lou, Jun,Yang, Xiaoyan,Rao, Zhigang,Qi, Wenwen,Li, Jinhui,Wang, Haiyu,Li, Yuxi,Li, Jinping,Wang, Zhiming,Hu, Xianming,Liu, Peng,Hong, Xuechuan
-
p. 466 - 473
(2014/07/21)
-
- Synthesis of nitrogen heterocycles via α-aminoalkyl radicals generated from α-silyl secondary amines under visible light irradiation
-
We have succeeded in the visible light-mediated synthetic use of α-aminoalkyl radicals derived from α-silyl secondary amines toward addition to α,β-unsaturated carbonyl compounds. The resulting γ-aminocarbonyl compounds are converted into γ-lactams and pyrroles in a one-pot process. This journal is the Partner Organisations 2014.
- Nakajima, Kazunari,Kitagawa, Mai,Ashida, Yuya,Miyake, Yoshihiro,Nishibayashi, Yoshiaki
-
supporting information
p. 8900 - 8903
(2014/08/05)
-
- Asymmetric michael addition of N-tert-butanesulfinyl imidate with α,β-unsaturated diesters: Scope and application to the synthesis of indanone derivatives
-
An additive-free and highly diastereoselective Michael addition reaction of an N-tert-butanesulfinyl imidate to α,β-unsaturated diesters has been developed using LDA as a base with good to excellent yields. The utility of this chemistry is further demonstrated by the asymmetric synthesis of 3-substituted indanone derivatives 8a, 8d, 8e, and 8i with high enantiomeric excess, which are potential building blocks for preparing biologically active lead compounds.
- Wang, Jinfang,Zhou, Yu,Zhang, Lei,Li, Zeng,Chen, Xianjie,Liu, Hong
-
supporting information
p. 1508 - 1511
(2013/06/27)
-
- Nickel(ii)-catalyzed enantioselective 1,3-dipolar cycloaddition of azomethine imines with alkylidene malonates
-
We demonstrated an asymmetric 1,3-dipolar cycloaddition of azomethine betaines with alkylidene malonates by using a chiral N,N'-dioxide- NiII complex as a catalyst. Both aromatic- and aliphatic-substituted alkylidene malonates were found to be suitable for the reaction. A range of transpyrazolone derivatives was exclusively obtained with excellent yields (up to 99% yield) and good enantioselectivities (up to 97% ee) under mild reaction conditions. The reaction could be carried out on a gram scale with the good results being maintained. Control experiments were performed to elucidate the specific diastereoselectivity of the reaction. The formation of single trans isomers was dominated by secondary orbital interactions between the ester groups of the dipolarophile and the azomethine imine. On the basis of the experimental results and previous reports, a possible catalytic model was assumed.
- Li, Jiangting,Lian, Xiangjin,Liu, Xiaohua,Lin, Lili,Feng, Xiaoming
-
supporting information
p. 5134 - 5140
(2013/07/05)
-
- Determination of thermodynamic affinities of various polar olefins as hydride, hydrogen atom, and electron acceptors in acetonitrile
-
A series of 69 polar olefins with various typical structures (X) were synthesized and the thermodynamic affinities (defined in terms of the molar enthalpy changes or the standard redox potentials in this work) of the polar olefins obtaining hydride anions, hydrogen atoms, and electrons, the thermodynamic affinities of the radical anions of the polar olefins (X ?-) obtaining protons and hydrogen atoms, and the thermodynamic affinities of the hydrogen adducts of the polar olefins (XH?) obtaining electrons in acetonitrile were determined using titration calorimetry and electrochemical methods. The pure Ci - 'C π-bond heterolytic and homolytic dissociation energies of the polar olefins (X) in acetonitrile and the pure Ci - 'C π-bond homolytic dissociation energies of the radical anions of the polar olefins (X?-) in acetonitrile were estimated. The remote substituent effects on the six thermodynamic affinities of the polar olefins and their related reaction intermediates were examined using the Hammett linear free-energy relationships; the results show that the Hammett linear free-energy relationships all hold in the six chemical and electrochemical processes. The information disclosed in this work could not only supply a gap of the chemical thermodynamics of olefins as one class of very important organic unsaturated compounds but also strongly promote the fast development of the chemistry and applications of olefins.
- Cao, Ying,Zhang, Song-Chen,Zhang, Min,Shen, Guang-Bin,Zhu, Xiao-Qing
-
p. 7154 - 7168
(2013/08/23)
-
- Chiral-Zn(NTf2)2-complex-catalyzed diastereo- and enantioselective direct conjugate addition of arylacetonitriles to alkylidene malonates
-
Chiral N,N′-dioxide/Zn(NTf2)2 complexes were demonstrated to be highly effective in the direct asymmetric conjugate addition of arylacetonitriles to alkylidene malonates under mild conditions. A wide range of substrates were tolerated to afford their corresponding products in moderate-to-good yields with high diastereoselectivities (82:18->99:1 d.r.) and enantioselectivities (81-99 % ee). The reactions performed well, owing to the high Lewis acidity of the metal triflimidate and a ligand-acceleration effect. The N,N′-dioxide also benefited the deprotonation process as a Bronsted base. The catalytic reaction could be performed on the gram-scale with retention of yield, diastereoselectivity, and enantioselectivity. The products that contained functional groups were ready for further manipulation. In addition, a possible catalytic model was proposed to explain the origin of the asymmetric induction. Copyright
- Yao, Jingjing,Liu, Xiaohua,He, Peng,Zhu, Yin,Lian, Xiangjin,Lin, Lili,Feng, Xiaoming
-
supporting information
p. 16424 - 16430
(2013/12/04)
-
- Catalytic, enantio- and diastereoselective synthesis of γ-butyrolactones incorporating quaternary stereocentres
-
A new, highly enantio- and diastereoselective catalytic asymmetric formal cycloaddition of aryl succinic anhydrides and aldehydes which generates paraconic acid (γ-butyrolactone) derivatives is reported.
- Manoni, Francesco,Cornaggia, Claudio,Murray, James,Tallon, Sean,Connon, Stephen J.
-
supporting information; experimental part
p. 6502 - 6504
(2012/07/31)
-
- Synthesis of novel 2, 5-dihydrofuran derivatives and evaluation of their anticancer activity
-
According to metal-catalyzed [3 + 2] cycloaddition reaction, we synthesized a series of novel 2, 5-dihydrofuran derivatives and evaluated their in vitro anti-cancer activities via MTT method. The bioassay showed that the majority of the resultant compounds exerted anti-tumor effect against four human cancer cell lines to various extents, which supported the rationale of the design. Compounds 9e and 10g showed the highest activity with broad anti-cancer spectrum, which were good candidates for further evaluation.
- Zhang, Yikai,Zhong, Hanyu,Wang, Tiantian,Geng, Dongping,Zhang, Mingfeng,Li, Ke
-
scheme or table
p. 69 - 80
(2012/03/26)
-
- A systematic study on Knoevenagel reaction and Nazarov cyclization of less reactive carbonyl compounds using rare earth triflates and its applications
-
A systematic study of Knoevenagel reaction and Nazarov cyclization was made on variety of less reactive carbonyl compounds such as β-ketoesters, 1,3-diketones and cyclic active methylene compounds using Yb(OTf)3 as the catalyst. Recycling study confirms reusability of the catalyst without much loss of activity.
- Ilangovan,Muralidharan,Maruthamuthu
-
experimental part
p. 1000 - 1006
(2012/02/05)
-
- Solvent-free Knoevenagel condensation over iridium and platinum hydroxyapatites
-
The Knoevenagel condensation between various aldehydes (benzaldehyde, p-methoxybenzaldehyde and 1-naphthaldehyde) and esters (ethylcyanoacetate, ethylacetoacetate and diethylmalonoester) was carried out under solvent-free condition in the presence of iridium or platinum hydroxyapatites as a catalyst.
- Pillai,Singh,Jonnalagadda
-
experimental part
p. 536 - 539
(2011/10/31)
-
- First bovine serum albumin-promoted synthesis of enones, cinnamic acids and coumarins in ionic liquid: An insight into the role of protein impurities in porcine pancreas lipase for olefinic bond formation
-
During studies on exploiting the catalytic promiscuity of crude porcine pancreas lipase (PPL) in ionic liquid for C=C bond formations, bovine serum albumin (BSA) was found to be competing for these reactions. After a detailed investigation, we establish that these transformations are possible by unspecific protein catalysis rather than catalytic promiscuity of "PPL" - a first insight into the role of protein impurities in crude enzyme. Thus, a novel and highly efficient, environmentally friendly approach involving synergistic catalysis by bovine serum albumin-1-butyl-3- methylimidazolium bromide (BSA-[bmim]Br) has been developed for the synthesis of (E)-α,β-unsaturated compounds including a one-pot cascade synthesis of cinnamic acids and coumarins via aldol, Knoevenagel and Knoevenagel-Doebner condensations.
- Sharma, Nandini,Sharma, Upendra K.,Kumar, Rajesh,Katoch, Nidhi,Kumar, Rakesh,Sinha, Arun K.
-
scheme or table
p. 871 - 878
(2011/06/19)
-
- Synthesis and anti-tumor activity of novel ethyl 3-aryl-4-oxo-3,3a,4,6- tetrahydro-1H-furo[3,4-c]pyran-3a-carboxylates
-
A series of ethyl 3-aryl-4-oxo-3,3a,4,6-tetrahydro-1H-furo[3,4-c]pyran-3a- carboxylates were prepared through the metal-catalyzed domino reaction of alkylidene malonates and 1,4-butynediol under a one-pot reaction condition at room temperature. Their in vitro anti-proliferative activities were subsequently evaluated in A549, QGY and HeLa cells. The majority of the compounds showed potent anti-tumor activity against HeLa cells. In particular, compound 3l was the most potent compound with IC50 value of 5.4 μM. For the first time, the X-ray structure of the anti-tumor ethyl 3-aryl-4-oxo-3,3a,4,6- tetrahydro-1H-furo[3,4-c]pyran-3a-carboxylates is determined.
- Wang, Tiantian,Liu, Jia,Zhong, Hanyu,Chen, Huan,Lv, Zhiliang,Zhang, Yikai,Zhang, Mingfeng,Geng, Dongping,Niu, Chunjuan,Li, Yongmei,Li, Ke
-
scheme or table
p. 3381 - 3383
(2011/06/24)
-
- Solvent-free knoevenagel condensation over cobalt hydroxyapatite
-
The Knoevenagel condensation between various aldehydes (benzaldehyde, 1-naphthaldehyde, p-bromobenzaldehyde and p-methoxybenzaldehyde) and esters (ethylcyanoacetate, ethylacetoacetate and diethylmalonoester) was carried out under solvent free condition in the presence of cobalt hydroxyapatite (CoHAp), as a catalyst. Good to excellent yields (35-96%) were obtained. The catalyst is found to be superior over fluorapatite and several other heterogeneous catalysts. The catalyst can be recycled at least 3 times. Copyright
- Pillai, Manoharan Karuppiah,Singh, Sooboo,Jonnalagadda, Sreekanth B.
-
experimental part
p. 3710 - 3715
(2010/12/25)
-
- Asymmetric cyanation of activated olefins with ethyl cyanoformate catalyzed by a modular titanium catalyst
-
"Chemical Equation Presented" Asymmetric cyanation of a class of easily available olefins with a favorable cyanide source ethyl cyanoformate (CNCOOEt) was realized by an interesting modular catalyst. High yields and ee values were obtained for a range of substrates under solvent-free and mild reaction conditions. The products obtained could be easily transformed to the enantioenriched useful intermediates 5,6, and pharmaceutically Important γ-aminobutyric acid 7.
- Wang, Jun,Li, Wei,Liu, Yanling,Chu, Yangyang,Lin, Lili,Liu, Xiaohua,Feng, Xiaoming
-
supporting information; experimental part
p. 1280 - 1283
(2010/06/15)
-
- An effcient protocol for accessing β-Amino dicarbonyl compounds through aza-Michael reaction
-
β-Amino dicarbonyl compounds comprise a class of useful ligands on the coordination chemistry. In view of their importance, an effcient and facile method for the synthesis of β-amino dicarbonyl compounds has been developed, exploring the aza-Michael addition reactions in an aqueous medium. It was possible to achieve good to excellent yields, along with regioselectivity, the substituted diethyl 2-(phenylmethyl)malonates that were easily isolated without any chromatographic purifcation. The correct confguration of two of these β-amino dicarbonyl compounds were confrmed by X-ray crystallography. A complementary mechanism of this aza-Michael protocol is proposed to explain the results obtained.
- Meskini, Ihssan,Toupet, Loi?c,Daoudi, Maria,Kerbal, Abdelali,Bennani, Brahim,Dixneuf, Pierre H.,Chohan, Zahid H.,Leite, Ana Cristina Lima,Hadda, Taibi Ben
-
experimental part
p. 1129 - 1135
(2010/10/21)
-
- First example of organocatalysis by polystyrene-supported PAMAM dendrimers: Highly efficient and reusable catalyst for knoevenagel condensations
-
This paper describes the first use of polystyrene-supported poly(amidoamine) (PAMAM) dendrimers as heterogeneous basic organocatalysts for carbon-carbon bond formation. Polystyrene-supported PAMAM dendrimers of first, second and third generations have been used as reusable base catalysts in Knoevenagel condensations of carbonyl compounds with active methylene compounds. The reactions proceed in short periods of time and with 100% selectivity. This novel catalyst eliminates the use of aromatic and halogenated solvents, as well as complex purification processes. The catalysts can be recycled ten times. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
- Krishnan, G. Rajesh,Sreekumar, Krishnapillai
-
supporting information; experimental part
p. 4763 - 4768
(2009/05/07)
-
- Sc(OTf)3-catalyzed smooth tandem [3+2] cycloaddition/ring opening of donor-acceptor cyclopropane 1,1-diesters with enol silyl ethers
-
Catalyzed by Lewis acids, donor-acceptor cyclopropane 1,1-diesters reacted with enol silyl ethers to afford 1,6-dicarbonyl compounds in moderate to excellent yields. This supplied a mild carbon-carbon bond-forming method from the ring opening of cyclopropanes. A smooth tandem [3+2] cycloaddition/ring opening process has been clearly proved by an independent experiment.
- Fang, Jie,Ren, Jun,Wang, Zhongwen
-
supporting information; body text
p. 6659 - 6662
(2009/04/07)
-
- The Knoevenagel reaction in water catalyzed by zwitterionic liquids
-
Three hydroxyl functionalized zwitterionic liquids (ZILs) were found to be novel recyclable catalysts for the Knoevenagel condensation between aldehydes or ketones and active methylene compounds in aqueous medium. Both aldehydes and ketones gave satisfactory results. The products could simply be separated from the catalysts/water, and the catalysts could be recycled six times without noticeably decreasing the catalytic activity.
- Fang, Dong,Fei, Zheng-Hao,Liu, Zu-Liang
-
experimental part
p. 799 - 803
(2009/09/28)
-
- Determination of the electrophilicity parameters of diethyl benzylidenemalonates in dimethyl sulfoxide: Reference electrophiles for characterizing strong nucleophiles
-
The second-order rate constants of the reactions of nine substituted diethyl benzylidenemalonates 1a-i with the carbanions 2a-e have been determined spectrophotometrically in dimethyl sulfoxide (DMSO). Product studies show that the nucleophiles attack regioselectively at the electrophilic C=C double bond of the Michael acceptors to form the carbanionic adducts 4. The correlation log k(20°C) = s(N+E) allows the determination of the electrophilicity parameters E for the electrophiles 1a-i from the rate constants determined in this work and the previously published N and s parameters for the nucleophiles 2a-e. The electrophilicities E for compounds 1a-i cover a range of six units (-17.7> E >-23.8) and correlate excellently with Hammett's substituent constants σp. The title compounds are roughly ten orders of magnitude less reactive than analogously substituted benzylidene Meldrum's acids, their cyclic analogues. Due to their low reactivities, compounds 1a-i are suitable reference electrophiles for determining the reactivities of highly reactive nucleophiles, such as carbanions with 16N30.
- Kaumanns, Oliver,Lucius, Roland,Mayr, Herbert
-
supporting information; experimental part
p. 9675 - 9682
(2009/09/29)
-
- A convenient synthesis of the (E)-monoacetates of 2-alkylidenepropane-1,3- diols
-
Various kinds of 3-substituted (E)-2-(hydroxymethyl)prop-2-enyl acetates were conveniently obtained in excellent yields by the regiospecific acetylation of 2-alkylidenepropane-1,3-diols with 10 equivalents of vinyl acetate in the presence of 50% w/w porcine pancreatic lipase (PPL) type II; the starting materials or (Z)-monoacetate or diacetate byproducts were generally not present. Georg Thieme Verlag Stuttgart.
- Miura, Tsuyoshi,Okazaki, Kenjiro,Ogawa, Kyoko,Otomo, Erika,Umetsu, Satoe,Takahashi, Mauko,Kawashima, Yuya,Jyo, Yuki,Koyata, Naka,Murakami, Yasuoki,Imai, Nobuyuki
-
body text
p. 2695 - 2700
(2009/04/04)
-
- Unprecedented reaction between ethyl α-cyanocinnamate and o-phenylenediamine: Development of an efficient method for the transfer hydrogenation of electronically depleted olefins
-
A reaction between ethyl α-cyanocinnamate and o-phenylenediamine under thermal conditions yielded 2-cyano-3-phenyl-propionic acid ethyl ester, 2-phenyl benzimidazole, and ethyl cyanoacetate. The mechanistic revelations led to the development of a simple and efficient transfer-hydrogenation process from the in situ generated benzimidazolines to activated olefins under solventless and catalyst-free conditions. Georg Thieme Verlag Stuttgart.
- Kumar, Satish,Kapoor, Kamal K.
-
p. 2809 - 2814
(2008/02/13)
-
- A facile experimental method to determine the hydride affinity of polarized olefins in acetonitrile
-
(Chemical Equation Presented) Choosing a suitable hydride reducing agent and thermodynamic analysis of reduction mechanisms is facilitated by experimental hydride affinities ΔHH-A, which are reported herein for 28 polarized olefins 1 in acetonitrile (see scheme). The method should also be applicable to ketones, aldehydes, and imines.
- Zhu, Xiao-Qing,Zhang, Min,Liu, Qiao-Yun,Wang, Xiao-Xiao,Zhang, Jian-Yu,Cheng, Jin-Pei
-
p. 3954 - 3957
(2007/10/03)
-
- An Efficient Knoevenagel Condensation Catalyzed by LaCl3.7H 2O in Heterogeneous Medium
-
Knoevenagel condensation was carried out in absence of solvent with a mild Lewis acid Lanthanum(III) chloride, to prepare substituted alkenes. A systematic study of the reaction to establish the generality of the method has been undertaken with various aldehydes and active methylene compounds.
- Narsaiah, A. Venkat,Nagaiah
-
p. 3825 - 3832
(2007/10/03)
-
- Organic Reactions in Ionic Liquids: Knoevenagel Condensation Catalyzed by Ethylenediammonium Diacetate
-
The moisture and air stable ionic liquids 1-butyl-3-methylimidazonium tetrafluoroborate [bmim]BF4 and 1-butyl-3-methylimidazonium hexafluorophosphate [bmim]PF6 were used as 'green' recycle alternatives to volatile organic solvents (VOCs) for ethylenediammonium diacetate (EDDA) catalyzed Knoevenagel condensation between aldehydes or ketones with active methylene compounds. Both aldehydes and ketones gave satisfactory results. The ionic liquids containing catalyst EDDA were recycled several times with no decrease in yields and reaction rates. In the case of 2-hydroxybenzaldehyde, the reactions led to the formation of 3-substituted coumarins under standard reaction conditions.
- Su, Ce,Chen, Zhen-Chu,Zheng, Qin-Guo
-
p. 555 - 559
(2007/10/03)
-
- Amidocarboxylic acid derivatives
-
Amidocarboxylic acid derivatives of the formula: wherein R1 represents a hydrogen atom, etc.; R2 represents an alkylene group; R3 represents a hydrogen atom, etc.; R4 represents a hydrogen atom, etc.; X represents a substituted or unsubstituted aryl group, etc.,; Y represents an oxygen atom, etc.; Z represents an alkylene group, etc.; and W represents an alkyl group, etc.; and pharmacologically acceptable salts thereof and pharmacologically acceptable esters thereof are useful as the active ingredient of pharmaceutical compositions. They may be used to treat specified diseases, including diabetes mellitus, hyperlipemia, arteriosclerosis, hypertension, etc.
- -
-
-
- Lewis acidic ionic liquids for the synthesis of electrophilic alkenes via the Knoevenagel condensation
-
1-Butyl-3-methylimidazolium chloroaluminate, [bmim]Cl·AlCl3, N = 0.67 and 1-butylpyridinium chloroaluminate, [bpy]Cl·AlCl3, N = 0.67 ionic liquids were found to work well as the Lewis acid catalyst and solvent in the Knoevenagel condensations of benzaldehyde and substituted benzaldehydes with diethyl malonate to give benzylidene malonates. The benzylidene malonates subsequently underwent Michael additions with diethyl malonate. The extent of Michael product formed during the reaction was found to vary with the Lewis acidity and the molar proportion of ionic liquid. The influence of Lewis acidity of the ionic liquid on the Knoevenagel and Michael products is demonstrated. In the case of 2-hydroxyarylaldehydes, the reactions led to the formation of 3-ethoxycarbonyl coumarins under ambient conditions.
- Harjani, Jitendra R,Nara, Susheel J,Salunkhe, Manikrao M
-
p. 1127 - 1130
(2007/10/03)
-
- Compositions comprising a dibenzoylmethane derivative, a 1,3,5-triazine derivative and a dialkyl benzalmalonate, and methods of use therefor
-
The present invention relates to novel cosmetic and/or dermatological compositions comprising, in a cosmetically and/or dermatologically acceptable support, i) a dibenzoylmethane derivative, in particular 4-tert-butyl-4'-methoxydibenzoylmethane, ii) at least one specific 1,3,5-triazine derivative, and iii) at least one dialkyl benzalmalonate. These compositions are particularly photostable. The invention also relates to the use of these compositions in the cosmetic and/or dermatological fields, in particular, as a sunscreen.
- -
-
-
- Three partners of a one pot palladium-mediated synthesis of various tetrahydrofurans
-
Substituted furans are obtained in a one step procedure from addition of allylic alkoxides to Michael accepters followed by a palladium catalysed cyclisation involving iodo-aryl compounds.
- Cavicchioli,Sixdenier,Derrey,Bouyssi,Balme
-
p. 1763 - 1766
(2007/10/03)
-
- Application of microwave irradiation techniques for the Knoevenagel condensation
-
The reaction rate of Knoevenagel condensation can be dramatically enhanced by irradiating the reaction mixture containing an aldehyde, diethyl malonate, P2O5, piperidine, and chlorobenzene with a commercial microwave oven. Six Knoevenagel condensation products were synthesized within 5-15 min in good yields.
- Kim, Jae-Kon,Kwon, Pan-Suk,Kwon, Tae-Woo,Chung, Sung-Kee,Lee, Jae-Wook
-
p. 535 - 542
(2007/10/03)
-
- Clay-mediated Synthesis of gem-Bis(alkoxycarbonyl) Alkenes under Microwave Irradiation
-
Diethyl and dimethyl malonate react selectively with aldehydes to afford alkenes within a few minutes, by adsorption on acidic clay (Montmorillonite K10) in a solvent-free reaction under microwave irradiation in a domestic oven.
- Ayoubi, Sahar Abdallah-El,Texier-Boullet, Francoise
-
p. 208 - 209
(2007/10/03)
-
- Knoevenagel condensation catalyzed by a Mexican bentonite using infrared irradiation
-
Diethyl malonate undergoes condensation with aromatic aldehydes without solvents, in the presence of a Mexican bentonite using infrared irradiations as the energy source, to give the benzylidenemalonate compounds in fair yield.
- Delgado,Tamariz,Zepeda,Landa,Miranda,Garcia
-
p. 753 - 759
(2007/10/02)
-
- A novel class of enkephalinase inhibitors containing a C-terminal sulfo group
-
A new series of sulfonic acids were synthesized and tested for their enkephalinase inhibitory activity. Among them, the most potent was N-(2- benzyl-3-mercaptopropionyl)metanilic acid 10i with an IC50 value of 0.27 nM. Several other analogues (10a,b,j,n,o,gg,hh) showed the inhibitory activity comparable to or greater than thiorphan (IC50 = 2.6 nM), a C- terminal carboxyl-containing inhibitor of enkephalinase. Thus compounds containing a C-terminal sulfo group, instead of the C-terminal carboxyl group, were found to show a remarkably high level of inhibition of enkephalinase. The analgesic activity of 10b, (S)-10b, and (R)-10b was also evaluated by the phenylbenzoquinone writhing test.
- Mimura,Nakamura,Nishino,Sawayama,Komiya,Deguchi,Kita,Nakamura,Matsumoto
-
p. 602 - 608
(2007/10/02)
-
- A novel olefination of carbonyl compounds with dibromo-malonate promoted by dibutyl telluride
-
α,β-Unsaturated malonic esters are conveniently synthesized from the reaction of dibromomalonate with carbonyl compounds promoted by dibutyl telluride in excellent yields. A possible mechanism involving twice halophilic attacks of dibutyl telluride is proposed. This methodology provides a facile route to α,β-unsaturated malonic esters and represents an alternative to the Knoevenagel reaction.
- Zhou,Shi,Huang
-
p. 1027 - 1037
(2007/10/02)
-
- α,β-Unsaturated esters from the tri-n-butylarsine-promoted reaction of bromomalonic esters with aldehydes
-
A convenient synthesis of α,β-unsaturated esters (in 68-96percent yields) from the reaction of a bromomalonic ester with aldehydes promoted by tri-n-butylarsine is descriebed.A mechanism involving halophilic attack of tri-n-butylarsine leading to the formation of a salt followed by reaction with carbonyl compounds is proposed.This methodology provides a convenient route to α,β-unsaturated esters and represents an alternative to the Knoevenagel reaction.
- Shen, Yanchang,Yang, Baozhen
-
-
- Synthesis of 3-Aryl-1-tetralones
-
A new method for the synthesis of 3-aryl-1-tetralones is presented.The tetralones synthesised have been characterised by elemental analysis and soectral data.
- Selvaraj, S.,Rajendran, A. S.,Arumugam, N.
-
p. 1047 - 1049
(2007/10/02)
-
- SYNTHESE RADICALAIRE D'ANALGESIQUES POTENTIELS: ARYL-4 PIPERIDINES SUBSTITUEES EN 2 ET BENZOMORPHANES
-
The synthesis of a series of 3-aryl 5-hexenyl amines and the cyclisations of the corresponding N-chloroamines are described.When the ring closure results from the amino radical addition to the ethylenic double bond, 2-chloromethyl 4-phenyl piperidines are obtained.These compounds lead by intramolecular Friedel-Crafts reaction to varied substituted 6,7-benzomorphanes.When the phenyl ring is substituted with a methoxyl group, the cyclisation proceeds via homolytic aromatic substitution and 4-allyl tetrahydroquinolines are formed.
- Stella, L.,Raynier, B.,Surzur, J. M.
-
p. 2843 - 2854
(2007/10/02)
-