- A Facile Approach to the Synthesis of Benzothiazoles from N-Protected Amino Acids
-
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.
-
p. 292 - 297
(2020/04/21)
-
- Synthesis and anti-tumor activity evaluation of novel 7-fluoro-4-(1-piperazinyl) quinolines
-
Background: Three series of new 7-fluoro-4-(1-piperazinyl) quinolines (I1~I6, II1~II2 and IV1~IV4) were synthesized. Their anti-tumor activity was evaluated in vitro against three human carcinoma cell lines, namely SGC-7901 cells, BEL-7402 cells and A549 cells expressing high levels of EGFR by Methyl Thiazolyl Terazolium (MTT) assay. Methods: Three series of quinoline derivatives were synthesized, characterized and evaluated for their in vitro anti-tumor activities. Results and Discussion: Structures of the newly synthesized compounds were confirmed by spectral analysis. The preliminary bioassay indicated that compounds I1, I10 and II1 exhibited better anti-tumor activity than the rest of the target compounds and gefitinib against A549 cell based assay, which demonstrated that compounds I1, I10 and II1 are potential agents for cancer therapy. Results suggested that the substitutes on piperazinyl influenced anti-tumor activities remarkably. Conclusion: These results are useful for discovering more potent novel anti-tumor compounds and further studies are ongoing.
- Liu, Dan,Xue, Aiqi,Liu, Zhixin,Zhang, Yi,Peng, Penghui,Wang, Haifeng
-
p. 663 - 669
(2019/06/24)
-
- Tertiary-butoxycarbonyl (Boc) – A strategic group for N-protection/deprotection in the synthesis of various natural/unnatural N-unprotected aminoacid cyanomethyl esters
-
A number of cyanomethyl esters of natural/unnatural aminoacids with un-protected amino functionality were synthesized because of their synthetic and medicinal importance. Critical N-Boc deprotection methods in the presence of labile (hydrolytic sensitivity) cyanomethyl functionality were screened thoroughly and it was found that readily available 4M HCl in 1,4-dioxane solution (2–4 equiv); acetonitrile, 0 °C, 2–4 h was a suitable condition. This condition was generalized and successfully applied to a variety of alkyl, alkynyl, aryl, heteroaryl, benzyl, azido, spiro amino acid cyanomethylesters irrespective of the nature of the amine (primary or secondary) and the distance between the amine and ester group to achieve final deprotected amino esters with high yield, and purity compared to other commonly known N-protecting groups (Cbz, Fmoc, Ac, Bn, Bz etc.). It was also demonstrated that N-Boc protected aminoacid cyanomethylesters are stable enough to carry out further functionalization compared to N-unprotected counterparts.
- Karmakar, Ananta,Basha, Mushkin,Venkatesh Babu,Botlagunta, Murali,Malik, Noormohamed Abdul,Rampulla, Richard,Mathur, Arvind,Gupta, Arun Kumar
-
supporting information
p. 4267 - 4271
(2018/11/03)
-
- Amino acid conjugated antimicrobial drugs: Synthesis, lipophilicity- activity relationship, antibacterial and urease inhibition activity
-
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
-
p. 140 - 153
(2018/01/10)
-
- Visible Light Photorelease of Carboxylic Acids via Charge-Transfer Excitation of N-Methylpyridinium Iodide Esters
-
Iodide contrast sensitization to direct irradiation of charge transfer salts incurs carboxylic acid release via visible light absorption. The photochemical reduction of N-methyl-4-pyridinium iodide esters to release carboxylic acids is examined using 1H NMR analysis. Photolysis reactions are carried out under mild, biphasic solvent conditions using a household LED lamp. Carboxylic acid release is reported in high yields, and the viability of this method for synthetic chemistry is demonstrated through a macroscale reaction.
- Kunsberg, David J.,Kipping, Allison H.,Falvey, Daniel E.
-
p. 3454 - 3457
(2015/07/28)
-
- Iron-catalyzed oxidative C - H/C - H cross-coupling: An efficient route to α-quaternary α-amino acid derivatives
-
Fully loaded: A coordinating activation strategy has been developed to furnish α-quaternary α-amino acids through the iron(III)-catalyzed oxidative functionalization of α-C(sp3) - H bonds of α-tertiary α-amino acid esters. The reaction exhibits a broad substrate scope for both α-amino acids and nucleophiles (Nu) as well as good functional-group tolerance (see scheme, DTBP=di-tert-butyl peroxide, DCE=1,2-dichloroethane). Copyright
- Li, Kaizhi,Tan, Guangying,Huang, Jingsheng,Song, Feijie,You, Jingsong
-
supporting information
p. 12942 - 12945
(2014/01/06)
-
- Enantiomeric resolution of α-amino acid derivatives on two diastereomeric chiral stationary phases based on chiral crown ethers incorporating two different chiral units
-
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
-
body text
p. 1551 - 1554
(2010/10/20)
-
- Kinetic resolution of racemic carboxylic acids by an L-histidine-derived sulfonamide-induced enantioselective esterification reaction
-
(Chemical Equation Presented) The direct and catalytic kinetic resolution of racemic carboxylic acids bearing a Bronsted base such as O-protected α-hydroxy carboxylic acids and N-protected α-amino acids has been accomplished through an L-histidine-derived sulfonamide-induced enantioselective esterification reaction with tert-butyl alcohol for the first time. Highly asymmetric induction [S(kfast/kslow) = up to 56] has been achieved under the equilibrium between a chiral catalyst and two diastereomeric acylammonium salts through an intramolecular hydrogen-bonding interaction.
- Ishihara, Kazuaki,Kosugi, Yuji,Umemura, Shuhei,Sakakura, Akira
-
supporting information; experimental part
p. 3191 - 3194
(2009/05/27)
-
- Useful reagents for introduction of Boc and Fmoc protective groups to amines: Boc-DMT and Fmoc-DMT
-
New amino-protecting reagents, Boc-DMT and Fmoc-DMT, were prepared, and found to be useful for the introduction of Boc and Fmoc groups into amines. Both the reagents can protect various amines including amino acids in good yield in aqueous media. Since the reagents are neither unstable nor irritating, they are practically useful. Georg Thieme Verlag Stuttgart.
- Hioki, Kazuhito,Kinugasa, Mizuho,Kishimoto, Michiko,Fujiwara, Miho,Tani, Shohei,Kunishima, Munetaka
-
p. 1931 - 1933
(2007/10/03)
-
- Enzymatic removal of carboxyl protecting groups. 1. Cleavage of the tert-butyl moiety
-
(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
-
p. 3737 - 3740
(2007/10/03)
-
- Chiral gelators constructed from 11-aminoundecanoic (AUDA), lauric and amino acid units. Synthesis, gelling properties and preferred gelation of racemates vs. the pure enantiomers
-
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
-
p. 4048 - 4059
(2007/10/03)
-
- ARYLGLYCINE DERIVATIVES FOR USE AS GLYCINE TRANSPORT INHIBITORS
-
The present invention relates to compounds of Formula (I) and salts solvates and hydrates thereof. The invention further relates to pharmaceutical compositions containing said compounds and methods of treating neurological and neuropsychistric disorders using said compounds.
- -
-
-
- Efficient electrochemical deprotection of carboxylic and amino acids from their 2-(hydroxymethyl)-1,3-dithiane (dim) esters
-
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.
-
p. 799 - 801
(2007/10/03)
-
- Protecting Groups that can be Removed through Photochemical Electron Transfer: Mechanistic and Product Studies on Photosensitized Release of Carboxylates from Phenacyl Esters
-
Photolysis of electron-donating photosensitizers in the presence of various phenacyl esters (PhCOCH2-OCOR) results in C-O bond scission leading to the formation of acetophenone (PhCOCH3) and the corresponding carboxylic acid (RCO2H). Preparative experiments showed that the carboxylic acids are generated in high or quantitative isolated yields. It is argued that this reaction is initiated by a photoinduced electron transfer from the excited state sensitizer to the phenacyl ester. The latter process forms the anion radical of the phenacyl ester which in turn undergoes rapid C-O bond scission leading to the phenacyl radical and the corresponding carboxylate anion. This mechanism is supported by the following observations. (1) The phenacyl esters quench fluorescence from the sensitizers. (2) Analysis of the redox potentials of the sensitizer excited states and the substrates shows that the proposed electron transfer step is exergonic by 15-20 kcal/mol. (3) The byproducts are indicative of the proposed ion radical intermediates. In particular N-methylaniline is detected when N4Y-dimethylaniline is used as a sensitizer. (4) Competing processes are observed in phenacyl esters whose acid components are themselves labile to single-electron transfer. For example, phenacyl 4-bromophenylacetate showed bromide elimination in competition with deprotection.
- Banerjee, Anamitro,Falvey, Daniel E.
-
p. 6245 - 6251
(2007/10/03)
-
- Direct synthesis of Boc protected (D,L)-amino acids from Boc-glycine
-
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
-
p. 6461 - 6464
(2007/10/02)
-
- t-Butyl Benzotriazol-1-yl Carbonate. A New Efficient Reagent for t-Butoxycarbonylation of Amino Acids
-
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
-
p. 1357 - 1358
(2007/10/02)
-
- PEPTIDE BOND FORMATION BY INTERMOLECULAR AMINOLYSIS OF D-GLUCOPYRANOSYL ESTERS OF AMINO ACIDS
-
The reaction of HO-protected and -unprotected D-glucopyranosyl esters of N-acylamino acids (Gly, Ala, Phe) with glycine and phenylalanine methyl esters in N,N-dimethylformamide at 38 deg C and dichloromethane at 40 deg C, respectively, led to repture of the C-1 ester bond and formation of the corresponding N-acyldipeptide methyl ester.The relative reactivity of the C-1 ester bond toward aminolysis was greatly influenced by the structure of the amino acid nucleophile, the nature of the aglycon side-chain group, and the anomeric configuration of the D-glucopyranosyl ester involved.Evidence for a substantially lower acylating efficiency of the ester at C-2, as compared to that at C-1, was obtained by aminolysis of two fully acetylated 2-O-(acylaminoacyl)-β-D-glucopyranoses.Treatment of 1-O-(glycylglycylglycyl)-β-D-glucopyranose with phenylalanine methyl ester in N,N-dimethylformamide led to parallel hydrolysis and intermolecular aminolysis, to give the tripeptide and tetrapeptide methyl ester.
- Horvat, Stefica,Keglevic, Dina
-
-