- Unprecedented stereoselectivity in the Staudinger reaction with polycyclic aromatic imines
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Cycloaddition of imines derived from polycyclic aromatic amines with acid chloride (or equivalent) in the presence of triethylamine at -78°C to room temperature unexpectedly produced trans-β-lactams. (C) 2000 Elsevier Science Ltd.
- Banik,Becker
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Read Online
- Stereoselective synthesis of-lactams under diverse conditions: Unprecedented Observations
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ferent reaction conditions have been used for this study. It is important to note that the stereochemistry of the-lactam formation reaction depends on the conditions of the experiments, structures of the imines and acid chlorides, order of addition of the
- Das, Aparna,Bose, Ajay K.,Banik, Bimal Krishna
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p. 917 - 925
(2020/12/04)
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- Microwave-induced cycloaddition of imines with acid chlorides in absence of a tertiary amine: Unprecedented synthesis of β-lactams in dimethylformamide
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Synthesis β-lactams in N,N-dimethylformamide proceeds through cycloaddition of acid chlorides with imines in a domestic microwave oven in the absence of a tertiary base. This is an unprecedented observation.
- Yadav, Ram Naresh,Chavez, Ashlee,Banik, Bimal Krishna
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p. 1365 - 1367
(2020/06/27)
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- Synthesis and biological evaluation of novel larotaxel analogues
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Taxoids are a class of successful drugs and have been successfully used in chemotherapy for a variety of cancer types. However, despite the hope and promises that these taxoids have engendered, their utility is hampered by some clinic limitations. Extensive structure-activity relationship (SAR) studies of toxoids have been performed in many different laboratories. Whereas, SAR studies that based on the new-generation toxoid, larotaxel, have not been reported yet. In view of the advantages in preclinical and clinical data of larotaxel over former toxoids, new taxoids that strategicly modified at the C3’/C3′-N and C2 positions of larotaxel were designed, semi-synthesized, and examined for their potency and efficacy in vitro. As a result, it has been shown that the majority of these larotaxel analogues are exceptionally potent against both drug-sensitive tumor cells and tumor cells with drug resistance arising from P-glycoprotein over expression. Further in vivo antitumor efficacies investigations revealed A2 might be a potent antitumor drug candidate for further preclinical evaluation.
- Ren, Sumei,Wang, Yujie,Wang, Junfei,Gao, Dingding,Zhang, Minmin,Ding, Ning,Li, Yingxia
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supporting information
p. 692 - 710
(2018/07/29)
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- Paclitaxel Biosynthesis: Adenylation and Thiolation Domains of an NRPS TycA PheAT Module Produce Various Arylisoserine CoA Thioesters
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Structure-activity relationship studies show that the phenylisoserinyl moiety of paclitaxel (Taxol) is largely necessary for the effective anticancer activity. Several paclitaxel analogues with a variant isoserinyl side chain have improved pharmaceutical
- Muchiri, Ruth,Walker, Kevin D.
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p. 1415 - 1425
(2017/03/23)
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- A mild and selective reduction of β-lactams: Rh-catalyzed hydrosilylation towards important pharmacological building blocks
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Four-membered N-heterocyclic compounds exhibit a broad range of pharmacological activities. Herein, we report a useful rhodium-catalyzed protocol for the activation of phenylsilane to reduce tertiary β-lactams. Reaction with the tertiary amides was select
- Bornschein, Christoph,Lennox, Alastair J. J.,Werkmeister, Svenja,Junge, Kathrin,Beller, Matthias
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supporting information
p. 1915 - 1919
(2015/03/18)
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- Stereospecific novel glycosylation of hydroxy β-lactams via iodine-catalyzed reaction: A new method for optical resolution
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Glycosylation of racemic and optically active α-hydroxy β-lactams by reaction with a few glycal derivatives in the presence of catalytic amounts of iodine has provided stereospecific formation of α-glycosides. This method has been extended for the prepara
- Banik, Bimal K.,Manhas, Maghar S.
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p. 10769 - 10779
(2013/01/15)
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- A new enzymatic strategy for the preparation of (2R,3S)-3-phenylisoserine: a key intermediate for the Taxol side chain
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Burkholderia cepacia lipase PS-IM catalysed the hydrolysis of racemic ethyl 3-amino-3-phenyl-2-hydroxypropionate with excellent enantioselectivity (E >200), when the reaction was performed with added H2O as a nucleophile, in iPr2O, at 50 °C. The hydrolysis of the less reactive enantiomeric ethyl 3-amino-3-phenyl-2-hydroxypropionate with 18% HCl afforded the corresponding enantiomerically pure (2R,3S)-3-amino-3-phenyl-2-hydroxypropionic acid hydrochloride, a key intermediate for the Taxol side chain.
- Forro, Eniko,Fueloep, Ferenc
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scheme or table
p. 637 - 639
(2010/08/03)
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- Arthrobacter sp.: a lipase of choice for the kinetic resolution of racemic arylazetidinone precursors of taxanoid side chains
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The native strain of Arthrobacter sp. (MTCC 5125) bearing a lipase has been found to be the most effective in the kinetic resolution of racemic arylazetidinones for producing cis-(3R,4S)-3-acetoxy-1-(4-methoxyphenyl)-4-phenyl-2-azetidinone, cis-(3R,4S)-3-
- Anand, Naveen,Kapoor, Munish,Ahmad, Khursheed,Koul, Surrinder,Parshad, Rajinder,Manhas, Kuldip S.,Sharma, Rattan L.,Qazi, Ghulam N.,Taneja, Subhash C.
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p. 1059 - 1069
(2008/01/07)
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- Reductive ring opening of 2-azetidinones promoted by sodium borohydride
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Variously substituted 2-azetidinones 3 and 4 were reacted with sodium borohydride in aqueous isopropanol giving 3-aminopropan-1,2-dioles 5 and 7. Reaction extent was dependent upon the substitution pattern in the 3- and 4-positions of the 2-azetidinone ri
- Del Buttero, Paola,Molteni, Giorgio,Roncoroni, Maurizio
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p. 2209 - 2211
(2007/10/03)
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- N-Methylthio β-lactam antibacterials: Effects of the C 3/C4 ring substituents on anti-MRSA activity
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N-Thiolated β-lactams are a new family of antibacterials that inhibit the growth of Staphylococcus bacteria. Unlike other β-lactam drugs, these compounds retain their full antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA) strains and operate through a different mode of action. The structural features, which give these lactams their biological activity, have not yet been completely defined. Earlier efforts in our laboratory established that the N-organothio substituent is essential for antimicrobial activity while other groups at C3 and C4 on the lactam ring play a more subtle role. In this present study, we investigate these effects by varying the polar and steric nature of the ring substituents at these two centers. From the data presented herein, it appears that there is a need to balance the lipophilic character of the C3/C4 groups to obtain an optimal anti-MRSA activity. The structure-bioactivity profiles more closely relate to the compound's ability to penetrate the bacterial cell membrane to sites of action within the cytoplasm rather than to any specific non-bonding interactions with a biological target. Based on these results, a model for the compounds' mode of action is presented.
- Turos, Edward,Coates, Cristina,Shim, Jeung-Yeop,Wang, Yang,Leslie, J. Michelle,Long, Timothy E.,Reddy, G. Suresh Kumar,Ortiz, Alex,Culbreath, Marci,Dickey, Sonja,Lim, Daniel V.,Alonso, Eduardo,Gonzalez, Javier
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p. 6289 - 6308
(2007/10/03)
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- An efficient and simple procedure for the preparation of α-keto-β-lactams
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The methods for the preparation of α-keto-β-lactams described in the literature are generally specific for a particular target molecule and lack generality. A short route to several of these compounds has been developed and is described in this communication. The protocol based on an efficient cyclization procedure followed by hydrolysis and oxidation allows preparation of α-keto-β-lactams 5a-g with sensitive substituents. Wiley-VCH Verlag GmbH, 2000.
- Mihovilovic, Marko D.,Feicht, Anton,Kayser, Margaret M.
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p. 585 - 590
(2007/10/03)
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- Enantiopure α-hydroxy-β-lactams via stereoselective glycosylation
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Stereospecific glycosylation via the Ferrier rearrangement catalyzed by iodine has been used to obtain both enantiomers of a trans 4-aryl-3-hydroxy-2-azetidinone. Unexpectedly, a rhamnal derivative had to be employed for this reaction since a glucal derivative failed to work. This synthesis complements our previously described preparation of the corresponding cis isomers by the same methodology. Thus, convenient access has become available to all four homochiral stereoisomers of α-hydroxy-β-lactams some of which are synthons for Taxol and analogs.
- Banik, Bimal K.,Manhas, Maghar S.,Bose, Ajay K.
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p. 5077 - 5080
(2007/10/03)
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- Synthesis of 3-acetoxyazetidin-2-ones and 3-hydroxyazetidin-2-ones with antifungal and antibacterial activity
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The synthesis of a series of 3-acetoxyazetidin-2-ones 3a-n and 3-hydroxyazetidin-2-ones 6a-j is reported together with the antibacterial and antifungal evaluation of these compounds. An additional series of 3-acetoxyazetidin-2-ones 11a-h which possess a free carboxylic acid group on the N-1 aryl ring were obtained by treatment of suitably substituted Schiff bases 10a-h with acetoxyacetyl chloride. The novel bicyclic structures 7-acetoxy-6-phenyl-5-thia-1-azabicyclo[4.2.0]octan-8-one 13 and 7-hydroxy-6-phenyl-5-thia-1-azabicyclo[4.2.0]octan-8-one 14 were also obtained. Many of the compounds displayed antifungal activity in vitro when evaluated against the pathogenic fungi Cryptococcus neoformans, Candida albicans, Candida tropicalis, Candida parapsilosis, Candida glabrata, and Trichosporon cutaneum, while 3-acetoxyazetidin-2-ones 11a-h containing a free carboxylic acid group on the N-1 aryl ring displayed antibacterial activity against Staphylococcus aureus, Proteus vulgaris, Pseudomonas aeruginosa, Bacillus subtilis, Klebsiella aerogenes and Escherischia coli.
- Walsh,Meegan,Prendergast,Al Nakib
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p. 989 - 1000
(2007/10/03)
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- Optically active aminoalcohol promoted addition of 2-pyridylthioester boron enolates to imines: Enantioselective one-pot synthesis of β-lactams
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The enolates derived from 2-pyridylthioesters by treatment with BCl3·Me2S and enantiomerically pure aminoalcohols react with aromatic and heteroaromatic imines to afford β-lactams in a convenient one-pot procedure and in up to 78% e.
- Annunziata, Rita,Benaglia, Maurizio,Cinquini, Mauro,Cozzi, Franco,Molteni, Valentina,Raimondi, Laura
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p. 8941 - 8952
(2007/10/02)
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- Synthesis of β-lactams by condensation of the tin enolates of 2-pyridylthioesters with imines. A comparison between titanium and tin enolates
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Addition of triethylamine to a mixture of 2-pyridylthioesters and SnCl4 or SnBr4 affords the corresponding tin(IV) enolates that add to imines to give β-lactams in fair to good yields and with various degree of trans/cis stereoselectivity. Examples of highly diastereofacially selective reactions carried out on a chiral thioester and on a chiral imine are also reported. The results are compared with those obtained in the condensations promoted by TiCl4 and TiBr4.
- Annunziata, Rita,Benaglia, Maurizio,Cinquini, Mauro,Cozzi, Franco,Raimondi, Laura
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p. 5821 - 5828
(2007/10/02)
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- Highly stereoselective synthesis of α-hydroxy β-amino acids through β-lactams: Application to the synthesis of the taxol and bestatin side chains and related systems
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Formation of α-hydroxy β-lactams, followed by chemical elaboration at C4 and further β-lactam cleavage afforded functionalised α-hydroxy β-amino acids or their derivatives in a highly stereoselective manner.
- Palomo,Arrieta,Cossio,Aizpurua,Mielgo,Aurrekoetxea
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p. 6429 - 6432
(2007/10/02)
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