- A Facile Approach to the Synthesis of Benzothiazoles from N-Protected Amino Acids
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Abstract: –A simple trituration method for the synthesis of 2-substituted benzothiazoles derived from N-protected amino acids and 2-aminothiophenol using molecular iodine as a mild Lewis acid catalyst has been proposed. The reaction occurs in one step for 20–25 min in solve-free conditions and provides the target products in excellent yields.
- Arfan, M.,Fatima, T.,Mannan, A.,Tahira, A.
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p. 292 - 297
(2020/04/21)
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- HMOX1 inducers
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The present invention is related to compounds of structure (I) as heme oxygenase 1 (HMOX 1) inducers. The present invention is also related a method of controlling the activity or the amount, or both the activity and the amount, of heme-oxygenase 1 in a mammalian subject. The definitions of the variables are provided herein.
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Page/Page column 59
(2020/09/18)
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- Amino acid conjugated antimicrobial drugs: Synthesis, lipophilicity- activity relationship, antibacterial and urease inhibition activity
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Present work describes the in vitro antibacterial evaluation of some new amino acid conjugated antimicrobial drugs. Structural modification was attempted on the three existing antimicrobial pharmaceuticals namely trimethoprim, metronidazole, isoniazid. Twenty one compounds from seven series of conjugates of these drugs were synthesized by coupling with some selected Boc-protected amino acids. The effect of structural features and lipophilicity on the antibacterial activity was investigated. The synthesized compounds were evaluated against five standard American type culture collection (ATCC) i.e. Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa and Salmonella typhi strains of bacteria. Our results identified a close relationship between the lipophilicity and the activity. Triazine skeleton proved beneficial for the increase in hydrophobicity and potency. Compounds with greater hydrophobicity have shown excellent activities against Gram-negative strains of bacteria than Gram-positive. 4-amino unsubstituted trimethoprim-triazine derivative 7b have shown superior activity with MIC = 3.4 μM (2 μg/mL) for S. aureus and 1.1 μM (0.66 μg/mL) for E. coli. The synthesized compounds were also evaluated for their urease inhibition study. Microbial urease from Bacillus pasteurii was chosen for this study. Triazine derivative 7a showed excellent inhibition with IC50 = 6.23 ± 0.09 μM. Docking studies on the crystal structure of B. pasteurii urease (PDB ID 4UBP) were carried out.
- Ullah, Atta,Iftikhar, Fatima,Arfan, Muhammad,Batool Kazmi, Syeda Tayyaba,Anjum, Muhammad Naveed,Haq, Ihsan-ul,Ayaz, Muhammad,Farooq, Sadia,Rashid, Umer
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p. 140 - 153
(2018/01/10)
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- Enantioselective Synthesis of Quaternary Δ4- and Δ5-Dehydroprolines Based on a Two-Step Formal [3+2] Cycloaddition of α-Aryl and α-Alkyl Isocyano(thio)acetates with Vinyl Ketones
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A divergent synthesis of optically active quaternary Δ4- and Δ5-dehydro prolines is developed based on the first catalytic enantioselective conjugate addition of α-substituted isocyano(thio)acetates to vinyl ketones that is general for both α-aryl and α-alkyl isocyano(thio)acetates. The new tetrasubstituted C?N stereocenter is formed without the need of any metal salt due to a bifunctional tertiary amine/squaramide catalyst, featuring a bulky polyaryl sidearm and an unusually short squaramide diamide H???H interatomic distance in the solid state.
- Odriozola, Amaiur,Oiarbide, Mikel,Palomo, Claudio
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supporting information
p. 12758 - 12762
(2017/09/25)
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- Chemo- and Diastereoselective N-Heterocyclic Carbene-Catalyzed Cross-Benzoin Reactions Using N-Boc-α-amino Aldehydes
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N-Boc-α-amino aldehydes are shown to be excellent partners in cross-benzoin reactions with aliphatic or heteroaromatic aldehydes. The chemoselectivity of the reaction and the facial selectivity on the amino aldehyde allow cross-benzoin products to be obtained in good yields and good diastereomeric ratios. The developed method is utilized as the key step in a concise total synthesis of d-arabino-phytosphingosine.
- Haghshenas, Pouyan,Gravel, Michel
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supporting information
p. 4518 - 4521
(2016/09/28)
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- Liquid chromatographic resolution of amino acid esters of acyclovir including racemic valacyclovir on crown ether-based chiral stationary phases
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Valacyclovir, a potential prodrug for the treatment of patients with herpes simplex and herpes zoster, and its analogs were resolved on two chiral stationary phases (CSPs) based on (3,3′-diphenyl-1,1′-binaphthyl)-20-crown-6 covalently bonded to silica gel. In order to find out an appropriate mobile phase condition, various mobile phases consisting of various organic modifiers in water containing various acidic modifiers were applied to the resolution of valacyclovir and its analogs. When 30% acetonitrile in water containing any of 0.05 M, 0.10 M, or 0.15 M perchloric acid was used as a mobile phase, valacyclovir and its analogs were resolved quite well on the two CSPs with the separation factors (α) in the range of 2.49～6.35 and resolutions (RS) in the range of 2.95 ～ 12.21. Between the two CSPs, the CSP containing residual silanol protecting n-octyl groups on the silica surface was found to be better than the CSP containing residual silanol groups.
- Ahn, Seong Ae,Hyun, Myung Ho
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p. 268 - 273
(2015/03/18)
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- Highly enantioselective fluorescent recognition of amino acid derivatives by unsymmetrical salan sensors
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Novel unsymmetrical salan fluorescent sensors 2a and 2b have been designed and synthesized. The chiral recognition of N-Boc-protected amino acids by 2a and 2b has been investigated. Sensor 2a possesses higher sensitivity and enantioselectivity than sensor 2b does. Job analysis and nonlinear regression results show that 2a can form a 1:1 stoichiometric complex with a N-Boc-protected amino acid. The obtained response selectivities and the association constants indicate that 2a is a highly enantioselective and sensitive fluorescent sensor toward N-Boc-protected amino acids.
- Yang, Xia,Shen, Kang,Liu, Xuechao,Zhu, Chengjian,Cheng, Yixiang
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scheme or table
p. 4611 - 4614
(2011/10/01)
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- Enantiomeric resolution of α-amino acid derivatives on two diastereomeric chiral stationary phases based on chiral crown ethers incorporating two different chiral units
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Two diastereomeric chiral stationary phases (CSPs) were applied to the liquid chromatographic resolution of various racemic a-amino methyl esters, α-amino N,N-diethylamides and α-amino N-propylamides. The CSP incorporating (R)-3,3' -diphenyl-1,1' -binaphtyl and (R,R)-tartaric acid unit as chiral barriers did not show any chiral recognition. In contrast, the CSP incorporating (R)-3,3'-diphenyl-1,1'-binaphtyl and (S,S)-tartaric acid unit as chiral barriers was found to show excellent chiral recognition especially for the two enantiomers of a-amino N-propylamides. Some of a-amino methyl esters and α-amino N,N-diethylamides were also resolved on the CSP incorporating (R)-3,3'-diphenyl-1,1'-binaphtyl and (S,S)-tartaric acid unit. From these results it was concluded that the two chiral units composing the diastereomeric CSPs can show "matched" or "mismatched" effect on the chiral recognition according to their absolute stereochemistry.
- Kim, Hee Jin,Choi, Hee Jung,Cho, Yoon Jae,Hyun, Myung Ho
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body text
p. 1551 - 1554
(2010/10/20)
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- Synthesis and solid-phase application of suitably protected γ-hydroxyvaline building blocks
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(Chemical Equation Presented) Recently, an unexpected modified residue, γ-hydroxy-D-valine (D-Hyv), was identified within ribosomally expressed polypeptide chains of four conopeptides from the venoms of Conus gladiator and Conus mus. To assemble Hyv-conta
- Cudic, Mare,Mari, Frank,Fields, Gregg B.
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p. 5581 - 5586
(2008/02/09)
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- Enzymatic removal of carboxyl protecting groups. 1. Cleavage of the tert-butyl moiety
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(Chemical Equation Presented) A recent discovery that a certain amino acid motif (GGG-(A)X-motif) in lipases and esterases determines their activity toward tertiary alcohols prompted us to investigate the use of these biocatalysts in the mild and selective removal of tert-butyl protecting groups in amino acid derivatives and related compounds. An esterase from Bacillus subtilis (BsubpNBE) and lipase A from Candida antarctica (CAL-A) were identified as the most active enzymes, which hydrolyzed a range of tert-butyl esters of protected amino acids (e.g., Boc-Tyr-OtBu, Z-GABA-OtBu, Fmoc-GABA-O tBu) in good to high yields and left Boc, Z, and Fmoc-protecting groups intact.
- Schmidt, Marlen,Barbayianni, Efrosini,Fotakopoulou, Irene,Hoehne, Matthias,Constantinou-Kokotou, Violetta,Bornscheuer, Uwe T.,Kokotos, George
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p. 3737 - 3740
(2007/10/03)
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- Chiral gelators constructed from 11-aminoundecanoic (AUDA), lauric and amino acid units. Synthesis, gelling properties and preferred gelation of racemates vs. the pure enantiomers
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A new class of efficient low molecular weight gelator molecules has been designed by combining 11-aminoundecanoic acid (AUDA), lauric acid and aromatic and aliphatic amino acid units in the same molecule. This yields a special class of fatty acid amphiphiles with core chiral centres and hydrogen bonding sites. Some of the compounds with terminal carboxylic acid and sodium carboxylate functions exhibited ambidextrous gelation properties, being able to form gels both with highly polar solvents (water, DMSO) and also with highly lipophilic solvents, including two hydrocarbon fuels. At variance with several recent observations that the enantiomers are generally more efficient gelators than the corresponding racemates, some of the racemic gelators prepared in this work were found to be capable of gelling up to 16 times larger volumes of certain solvents than the pure enantiomers. Temperature-dependent FTIR and 1H NMR studies of the gels formed by derivatives with terminal carboxylic acid groups and lipophilic solvents revealed that intermolecular hydrogen bonding between amidic and carboxylic acid units was involved in the self-assembly of gel aggregates. Additional strong stabilization of the aggregates was observed in the gelators possessing terminal sodium carboxylate groups, and this was attributed to the electrostatic and ion-dipole interactions between the sodium carboxylate groups. This additional stabilization appears to be responsible for considerably higher thermal stability of the latter gels in relation to those formed by gelators with terminal carboxylic acid groups. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.
- Caplar, Vesna,Zinic, Mladen,Pozzo, Jean-Luc,Fages, Frederic,Mieden-Gundert, Gudrun,Voegtle, Fritz
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p. 4048 - 4059
(2007/10/03)
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- Efficient electrochemical deprotection of carboxylic and amino acids from their 2-(hydroxymethyl)-1,3-dithiane (dim) esters
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formula presented Carboxylic acids and amino acids are electrochemically deprotected from their 2-(hydroxymethyl)-1,3-dithiane (Dim) esters.
- Barnhurst, Loren A.,Wan, Yongqin,Kutateladze, Andrei G.
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p. 799 - 801
(2007/10/03)
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- Direct synthesis of Boc protected (D,L)-amino acids from Boc-glycine
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Boc-glycine is easily deprotonated by lithium diisopropylamide, yielding a trianion which is trapped with an electrophile to give access to Boc-(D,L)-amino acids.
- De Nicola,Einhorn,Luche
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p. 6461 - 6464
(2007/10/02)
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- A STEREOSELECTIVE SYNTHESIS OF N-BOC-α-AMINO ALCOHOLS AND α-AMINO ACIDS
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A sterteoselective synthesis of N-Boc-α-amino alcohols and α-amino acids via the addition of Grignard reagents to the chiral electrophilic glycine equivalent α-bromo-N-Boc-glycine(-)phenylmenthylester is described.
- Ermert, Philipp,Meyer, Jsabella,Stucki, Christoph,Schneebeli, Joerg,Obrecht, Jean-Pierre
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p. 1265 - 1268
(2007/10/02)
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- Composition containing a penem or carbapenem antibiotic and the use of the same
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Administration of an N-acylated amino acid in association with a penem or carbapenem antibiotic relieves or eliminates the renal problems associated with administration of the antibiotic alone. The amino acid derivative and antibiotic may be formulated together as a composition or administered separately, either simultaneously or sequentially.
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- DIISOPROPYLETHYLAMINE ELIMINATES DIPEPTIDE FORMATION DURING THE ACYLATION OF AMINO ACIDS USING BENZOYL CHLORIDE AND SOME ALKYL CHLOROFORMATES
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Acylation of amino acids using benzoyl chloride in aqueous alkali leads to benzoylamino acids containing one percent of benzoyldipeptide.Use of diisopropylethylamine instead of sodium hydroxide as base eliminates the side reaction responsible for the contaminant.Ethoxycarbonylamino acids are advantageously prepared in the same manner using ethyl chloroformate or diethyl dicarbonate.The latter gives rise to some N-substituted dipeptide when used in aqueous alkali.The method is unsatisfactory for the benzyloxycarbonylation of amino acids.Use of 9-fluorenylmethyl chloroformate and diisopropylethylamine gives the pure derivative of leucine in moderate yield.
- Chen, Francis M. F.,Benoiton, N. Leo
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p. 1224 - 1227
(2007/10/02)
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- Composition containing a penem or carbapenem antibiotic
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Administration of an N-acylated amino acid in association with a penem or carbapenem antibiotic relieves or eliminates the renal problems associated with administration of the antibiotic alone. The amino acid derivative and antibiotic may be formulated together as a composition or administered separately, either simultaneously or sequentially. The composition may be prepared by simple mixing.
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- Aggregation Behavior of Amphiphiles Functionalized with Dipeptide Segments and Enantioselective Ester Hydrolysis in Their Bilayer Membranes
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Four amphiphiles having dipeptide segments, which consist of one histidyl residue and another amino acid residue, and the dihexadecyl moiety for the double-chain segment (N+C5AlaHis2C16, N+C5LeuHis2C16, N+C5PheHis2C16, and N+C5HisAla2C16) were synthesized, and the aggregate morphology of them was characterized by electron microscopy and differential scanning calorimetry.The amphiphiles, which have the histidyl residue bound to the dihexadecylamine component (N+C5AlaHis2C16, N+C5LeuHis2C16, and N+C5PheHis2C16) formed both multi- and single-walled aggregates in the aqueous dispersion state, while their sonicated solutions involved only single-walled vesicles.On the other hand, the amphiphile, which has the alanyl residue bound to the dihexadecylamine component (N+C5HisAla2C16) afforded tubular aggregates in the aqueous dispersion.The hydrolysis of enantiomeric esters of various hydrophobic nature, which was carried out in the single-walled vesicles, showed relatively small enantioselectivity.The reasons for such catalytic performance of the vesicles were discussed from the kinetic and mechanistic viewpoints; the kinetic analysis being carried out on the basis of the organic pseudo-phase concept.
- Murakami, Yukito,Nakano, Akio,Ikeda, Hidetsugu,Imori, Toru,Akiyoshi, Kazunari
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p. 172 - 180
(2007/10/02)
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- t-Butyl Benzotriazol-1-yl Carbonate. A New Efficient Reagent for t-Butoxycarbonylation of Amino Acids
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t-Butyl benzotriazol-1-yl carbonate, a stable crystalline compound, is found to be exceedingly effective in the t-butoxycarbonylation of amino acids.
- Kim, Sunggak,Chang, Heung
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p. 1357 - 1358
(2007/10/02)
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