- STEREOSELECTIVE PREPARATION OF β-AMINO-ACYL IRON COMPLEXES FOR β-LACTAM SYNTHESIS
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The enolate derived from 5-C5H5)Fe(PPh3)(CO)(COCH3)> and n-butyl lithium reacts stereoselectively with imines to yield β-amino-acyl complexes which on oxidation give β-lactams.
- Broadley, Karen,Davies, Stephen G.
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- A highly efficient stereoselective synthesis of β-lactams
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An efficient strategy for a one-pot, single step synthesis of β-lactams employing an imidazolidinone based chiral auxiliary with various aldimines via asymmetric Mannich-type reaction has been described.
- Goyal, Sandeep,Pal, Anang,Chouhan, Mangilal,Gangar, Mukesh,Sarak, Sharad,Nair, Vipin A.
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- Indium-mediated facile synthesis of 3-unsubstituted β-lactams
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A simple synthesis of 3-unsubstituted β-lactams was achieved through indium-mediated reaction of imines with ethyl bromoacetate. An ultrasound-promoted synthesis of 3-unsubstituted β-lactam using ethyl bromoacetate, zinc and imines was reported. Imines obtained from arylalkylamines produced the β-lactams in higher yield than those obtained from aryl- or allylamines.
- Banik, Bimal K.,Ghatak, Anjan,Becker, Frederick F.
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- β-Lactam Formation by Ultrasound-promoted Reformatsky Type Reaction
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Ultrasound was found to promote the reaction between ethyl bromoacetate, zinc, and a Schiff base such that an excellent yield of β-lactams was obtained in a few hours at room temperature.
- Bose, Ajay K.,Gupta, Kavita,Manhas, M. S.
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- Enantioselective Synthesis of Cyclopropanone Equivalents and Application to the Formation of Chiral β-Lactams
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Cyclopropanone derivatives have long been considered unsustainable synthetic intermediates because of their extreme strain and kinetic instability. Reported here is the enantioselective synthesis of 1-sulfonylcyclopropanols, as stable yet powerful equivalents of the corresponding cyclopropanone derivatives, by α-hydroxylation of sulfonylcyclopropanes using a bis(silyl) peroxide as the electrophilic oxygen source. This work constitutes the first general approach to enantioenriched cyclopropanone derivatives. Both the electronic and steric nature of the sulfonyl moiety, which serves as a base-labile protecting group and confers crystallinity to these cyclopropanone precursors, were found to have a crucial impact on the rate of equilibration to the corresponding cyclopropanone. The utility of these cyclopropanone surrogates is demonstrated in a mild and stereospecific formal [3+1] cycloaddition with simple hydroxylamines, leading to the efficient formation of chiral β-lactam derivatives.
- Jang, Yujin,Johnson, J. Drake,Jung, Myunggi,Lindsay, Vincent N. G.,Poteat, Christopher M.,Williams, Rachel G.
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p. 18655 - 18661
(2020/08/21)
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- Copper-Catalyzed Oxidative Benzylic C(sp3)?H Cyclization for the Synthesis of β-Lactams
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β-Lactams are important structural motifs because of their ubiquity in natural products and pharmaceuticals. We report herein a Cu-catalyzed intramolecular oxidative C(sp3)?H amidation for the synthesis of β-lactams using tBuOOtBu. This method
- Nozawa-Kumada, Kanako,Saga, Satoshi,Matsuzawa, Yuta,Hayashi, Masahito,Shigeno, Masanori,Kondo, Yoshinori
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p. 4496 - 4499
(2020/04/10)
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- A Ball-Milling-Enabled Reformatsky Reaction
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An operationally simple one-jar one-step mechanochemical Reformatsky reaction using in situ generated organozinc intermediates under neat grinding conditions has been developed. Notable features of this reaction protocol are that it requires no solvent, no inert gases, and no pre-activation of the bulk zinc source. The developed process is demonstrated to have good substrate scope (39–82 % yield) and is effective irrespective of the initial morphology of the zinc source.
- Cao, Qun,Stark, Roderick T.,Fallis, Ian A.,Browne, Duncan L.
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p. 2554 - 2557
(2019/06/17)
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- Synthesis of Exclusively 4-Substituted β-Lactams through the Kinugasa Reaction Utilizing Calcium Carbide
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A new Kinugasa reaction protocol has been elaborated for the one-pot synthesis of 4-substituted β-lactams utilizing calcium carbide and nitrone derivatives. Calcium carbide is thereby activated by TBAF·3H2O in the presence of CuCl/NMI. The ease of synthesis and use of inexpensive chemicals provides rapid access of practical quantities of β-lactams exclusively substituted at position 4.
- Hosseini, Abolfazl,Schreiner, Peter R.
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supporting information
p. 3746 - 3749
(2019/05/24)
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- Microwave-mediated synthesis of 3-unsubstituted β-lactams with aqueous trimethylborane
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A new microwave-induced method for the preparation of 3-unsubstituted β-lactams is explored via aqueous trimethylborane-mediated reaction of the corresponding xanthates.
- Yadav, Ram Naresh,Banik, Indrani,Banik, Bimal Krishna
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p. 1381 - 1384
(2020/06/27)
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- Short and efficient route toward α-substituted N-arylazetidines from acetanilides via Mitsunobu reaction
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N-Arylazetidines are efficiently obtained in a three-step procedure, providing a wide diversity of derivatives on multigram scale with overall yields of 21-55%. Cheap or easily available acetanilides are used in an adapted aldolization with aldehydes, fur
- Kern, Nicolas,Hoffmann, Marie,Weibel, Jean-Marc,Pale, Patrick,Blanc, Aurélien
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p. 5519 - 5531
(2015/03/30)
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- Efficient and regioselective synthesis of 5-hydroxy-2-isoxazolines: Versatile synthons for isoxazoles, β-lactams, and γ-amino alcohols
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"Chemical Equation Presented" An efficient and highly regioselective protocol was developed for the preparation of 5-hydroxy2-isoxazolines, which have been proved to be versatile synthons for isoxazles, β-hydroxy oximes, and γ-amino alcohols. β-Lactams, commonly embedded in the skeletons of bioactive natural products, were also synthesized in two steps from β-hydroxy oximes, providing a new strategy for the synthesis of this kind of compounds.
- Tang, Shibing,He, Jinmei,Sun, Yongquan,He, Liuer,She, Xuegong
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supporting information; experimental part
p. 1961 - 1966
(2010/06/20)
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- Synthesis of β-lactams and β-aminoesters via high intensity ultrasound-promoted Reformatsky reactions
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Reformatsky reactions of an imine, an α-bromoester, zinc dust and a catalytic amount of iodine in dioxane under high intensity ultrasound (HIU) irradiation from an ultrasonic probe are explored. A series of 16 aldimines with varying electronic demands is
- Ross, Nathan A.,MacGregor, Robert R.,Bartsch, Richard A.
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p. 2035 - 2041
(2007/10/03)
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- Multiple component reactions: An efficient nickel-catalyzed Reformatsky-type reaction and its application in the parallel synthesis of β-amino carbonyl libraries
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Multiple-component condensations (MCC) where three or more reactants combine to afford a new core structure possessing the molecular features of its composite building blocks is a powerful method for the preparation of molecular diversity. We have developed an efficient, nickel-catalyzed, Reformatsky-type three-component condensation (3CC) reaction that affords β-amino carbonyl compounds. The scope of the reaction is demonstrated both in the gram and microscale settings; 15 β-amino esters, amides, and a ketone were prepared efficiently at the mmol scale, and a library of 64 β-amino carbonyl compounds was generated at the μmol scale.
- Adrian Jr., James C.,Snapper, Marc L.
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p. 2143 - 2150
(2007/10/03)
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- The synthesis of β-lactams via a one-pot Reformatsky reaction of imines promoted by Zn/Cp2TiCl2 (cat.)
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In the presence of Zn/Cp2TiCl2 (cat.) α-bromoacetates, γ-bromocrotonates or α-bromomethylacrylates react with imines in one-pot to form β-lactams, 3-vinyl-β-lactams or α-methylene-γ-lactams, respectively, at room temperature without
- Chen, Lei,Zhao, Gang,Ding, Yu
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p. 2611 - 2614
(2007/10/03)
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- Selective synthesis of β-amino esters and β-lactams by rhodium-catalyzed reformatsky-type reaction
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β-Amino esters and β-lactams are synthesized selectively from aldimines and ethyl bromoacetate by applying a simply modified rhodium-catalyzed Reformatsky-type reaction.
- Kanai, Kazuo,Wakabayashi, Hitoshi,Honda, Toshio
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- Differential effects of stereochemistry and C-4 substituents on the enantioselectivity of PLE and PPL catalysed hydrolysis of 3,4-disubstituted β-lactams
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Pig Liver Esterase (PLE) and Pig Pancreas Lipase (PPL)catalysed hydrolysis of (±) trans-3-carbethoxy and (±)cis-3-acetoxymethyl 4-substituted β-lactams revealed interesting dependence on C-3, C-4 stereochemistry and nature of C-4 substituents.
- Basak, Amit,Mahato, Tapan,Bhattacharya, Gautam,Mukherjee, Ballari
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p. 643 - 646
(2007/10/03)
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- 3-Methylidene-β-lactams as potential inhibitors of β-lactamases. Part 1: Synthesis of α-substituted derivatives from imines by Reformatzky reaction with chlorotrimethylsilane, silylation and Peterson olefination
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A new variation of the Reformatzky reaction with use of I2/zinc and chlorotrimethylsilane in THF and a shortened work-up is described allowing the synthesis of a wide variety of substituted β-lactams 3 in fairly good yield. These lactams are silylated according to the Peterson reaction yielding by reactions with appropriate carbonyl compounds E/Z-mixtures of the substituted 3-methylidene β-lactams 7, 8 and 10. The isomers are separated by CC and completely characterized by spectroscopic methods, mainly 1H NMR spectroscopy. Condensation of the 3-formyl methylidene derivative 10 with amines or malonate yields the conjugated products 11, and from the isopropylidene derivative 6 the pyridinium sulfonate 14 is prepared via 12 and 13. All methylidene β-lactams are prepared as model compounds for studying their activity against β-lactamases and for elucidating the mechanism of action.
- Guertler,Ruf,Johner,Otto
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p. 811 - 815
(2007/10/03)
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- REACTIVITY OF THE PYRIDYLTHIOSILYL ENOL ETHER - ROUTE TO Β-LACTONE AND Β-LACTAM
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A simple and facile method for β-lactone and β-lactam syntheses based on a Lewis acid promoted pyridylthiosilyl enol ether (1) addition to an aldehyde or Schiff base is described.
- Hirai, Koichi,Homma, Hiroshi,Mikoshiba, Isamu
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p. 281 - 282
(2007/10/02)
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- A New Synthesis of β-Phenylaminothioesters and β-Lactams Via Base-Induced Ring-Opening of 2-Phenyl-3-Aryl-5-Phenyl-Thioisoxazolidines
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1,3-Dipolar cycloaddition of phenyl vinyl sulfide to aryl N-phenyl, N-methyl, or N-t-butylnitrones affords 2-phenyl(or 2-methyl or 2-t-butyl)-3-aryl-5-phenylthioisoxazolidines according to the regioselectivity already known for the cycloaddition of not hi
- Nunno, Leonardo Di,Scilimati, Antonio
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p. 10965 - 10976
(2007/10/02)
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- The Reformatsky Type Reaction of Gilman and Speeter in the Preparation of Valuable β-Lactams in Carbapenem Synthesis: Scope and Synthetic Utility
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The preparation of apppropriately substituted 3-alkyl β-lactams from the Reformatsky type reaction of Gilman and Speeter is described.Treatment of Schiff bases derived from α-methylcinnamaldehyde and amines with ethyl α-bromobutyrate or ethyl α-bromoisova
- Palomo, Claudio,Cossio, Fernando P.,Arrieta, Ana,Odriozola, Jose M.,Oiarbide, Mikel,Ontoria, Jesus M.
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p. 5736 - 5745
(2007/10/02)
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- ELECTROCHEMICAL STUDIES ON Β-LACTAMS. PART 4. ELECTROACETYLATION OF Β-LACTAMS.
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Electroreduction of 3-bromo- and 3,3-dichloro-β-lactams 1 carried out at the potential of the first voltammetric peak and in the presence of acetic anhydride gives 3-acetyl-β-lactams 2.The electrosynthesis is highly stereoselective, as only the acetyl der
- Casadei, Maria Antonietta,Inesi, Achille,Moracci, Franco Micheletti,Occhialini, Donatella
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p. 6885 - 6890
(2007/10/02)
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- Electrochemical Studies on β-Lactams. Part 1. Electroreduction of 3-Halogeno-β-lactams
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The electrochemical reduction in aprotic solvents of 3-halogeno-β-lactams (1a-c) and (2a-c), with or without added proton donors or/and electrophiles, has been investigated.Without added substrates, the carbanion arising from the cleavage of the carbon-halogen bond undergoes protonation (mainly from the 'parent'molecule) and, completely, ring-opening reactions yielding the corresponding dehalogenated β-lactam and α,β-unsaturated amide.In the presence of proton donors (CH3CO2H) or electrophiles (CO2), the protonation and coupling reactions, respectively, become largely predominant, and the dehalogenated or carboxylated β-lactams are the main products.In the presence of BrCH2CH2CN the protonation reaction is preferred, and the dehalogenated β-lactam predominates over the substitution product.The high yields of 3-carboxy-β-lactams, a class of compounds not easily accessible by chemical methods, are noteworthy from a synthetic point of view.
- Casadei, Maria Antonietta,Moracci, Franco Micheletti,Inesi, Achille
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p. 419 - 424
(2007/10/02)
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- ETUDE DE CYCLOADDITIONS AUX ALLENES GEM-DIACTIVES PAR DEUX GROUPES ELECTROATTRACTEURS
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Allenes, when they have two electron-withdrawing groups on the same carbon, are closely related to ketenes and can be used as synthetic equivalents of these compounds.Several synthetic approaches are investigated, such as dehydrohalogenation reactions, and an analogue of the Wolff transposition of diazoketones.These allenes undergo readily cycloadditions with imines and diazoalkanes, leading to equivalents of β-lactams and cyclobutanones.
- Danion-Bougot, Renee,Danion, Daniel,Carrie, Robert
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p. 1953 - 1958
(2007/10/02)
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- Synthesis of β-Lactams via Ketene-Imine Cycloaddition Chiral Ketenes Bearing a 1,3-Dithiolane Ring
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The reaction of chlorides and ketenes derived from 1,3-dithiolane-2-carboxylic acid and Schiff's bases affords substituted β-lactams.Introduction of chirality into the dithiolane residue leads to diastereoface-differentiation in formation of the four-membered ring.
- Abramski, Wojciech,Belzecki, Czeslaw,Chmielewski, Marek
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p. 451 - 457
(2007/10/02)
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- Methylketene: Synthesis by Pyrolysis of Butanone and Reaction with Imines Yielding Methylated Azetidinones
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During the pyrolysis of acetone with a ketene lamp trace amounts of butanone and methylketene are produced.These compounds result from break-off reactions of radical reaction chains of acetone.Pyrolysis of butanone leads to a mixture of ketene (70percent) and methylketene (30percent).The latter reacts with imines to give methylated β-lactams.The rate of these cycloaddition reactions is several powers of ten greater than the one observed with ketene.The 8-methyl-5-azanonamdienes 7, 10, 26, and 31 are obtained in good yields when the corresponding diazepines are reacted with the pyrolysis gas of butanone.Similar experimental conditions lead to the methylated azetidinones 13, 15, 16, and 18 in moderate yields whereas the known thiazolines 19, 20, and 21 do not react at all.The action of 26 and 30 against several pathogenic bacterial strains was tested; however, no antibacterial properties could be detected.
- Streith, Jacques,Tschamber, Theophile
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p. 1393 - 1408
(2007/10/02)
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- METHYLKETENE, A MINOR BUT HIGHLY REACTIVE BYPRODUCT IN THE PYROLYSIS GAS OF ACETONE
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Methylketene was identified during the pyrolysis of acetone, and proved to be much more reactive than ketene: METHYL-β-LACTAMS were the dominant cycloaddition products when imines are reacted with the pyrolysis gas of acetone at ROOM TEMPERATURE.
- Tschamber, Theophile,Streith, Jacques
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p. 4503 - 4506
(2007/10/02)
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- Hydrolytic behavior of two β-lactams and their corresponding imidate salts. New evidence for stereoelectronic control
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The basic hydrolysis and the concurrent carbonyl-oxygen exchange of 18O-labelled N-phenyl-4-phenyl-2-azetidinone (5*) and N-2,6-dimethylphenyl-2-azetidinone (6*) have been studied. β-Lactam 5* was easily hydrolysed and showed no carbonyl-oxygen exchange with 0.1 N sodium hydroxide (dioxane - water, 9:1).Under the same conditions, β-lactam 6* gave no exchange and was found resistant to basic hydrolysis.Hydrolysis and exchange was observed when 6* was refluxed with 0.1 N and 1 N sodium hydroxide in water.The hydrolysis of the corresponding imidate salts 7 and 8 was also investigated.Under basic conditions, salt 7 gave and 8:2 mixture of ester amine 9 and β-lactam 5, while under acidic conditions the hydrochloride salt of ester amine 9 was the only product.Under basic conditions, the imidate salt 8 produced only the β-lactam 6, and under acidic conditions, a 3:7 mixture of the hydrochloride salt of 10 and β-lactam 6.Under stronger acidic conditions (>/=3 N HCl), 8 gave only the starting β-lactam 6.The results of these hydrolysis reactions are easily explained on the basis of the stereoelectronic theory for the cleavage of tetrahedral intermediates, and by taking into account that the nitrogen of tetrahedral intermediates must be either protonated under acidic conditions, or hydrogen bonded with the solvent under basic conditions in order to observe the cleavage of the C-N bond.
- Deslongchamps, Pierre,Caron, Maurice
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p. 2061 - 2068
(2007/10/02)
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