- Synthesis, experimental and theoretical photophysical study of proton transfer based oxazoline fluorophores. Potential tailor made optical sensors for enantiomeric detection in solution
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A series of oxazoline based compounds was obtained via amidation formation from salicylic acid derivatives and benzyl-protected L-threonine with good yields (50–90%). These compounds present absorption in the UV region (~300 nm) and fluorescence emission
- Santos, Fabiano S.,Zanotto, Gabriel M.,Argomedo, Luis M.Z.,Darbem, Mariana P.,Gon?alves, Paulo F.B.,Stefani, Helio A.,Rodembusch, Fabiano S.
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Read Online
- Use of remote acyl groups for stereoselective 1,2-: Cis -glycosylation with fluorinated glucosazide thiodonors
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Fluorinated glycans are valuable probes for studying carbohydrate-protein interactions at the atomic level. Glucosamine is a ubiquitous component of glycans, and the stereoselective synthesis of α-linked fluorinated glucosamine is a challenge associated with the chemical synthesis of fluorinated glycans. We found that introducing a 6-O-acyl protecting group onto 3-fluoro and 4-fluoro glucosazide thiodonors endowed them with moderate α-selectivity in the glycosylation of carbohydrate acceptors, which was further improved by adjusting the acceptor reactivity via O-benzoylation. Excellent stereoselectivity was achieved for 3,6-di-O-acyl-4-fluoro analogues. The glycosylation of threonine-derived acceptors enabled the stereoselective synthesis of the protected fluorinated analogue of α-GlcNAc-O-Thr, a moiety abundant in cell-surface O-glycans of the protozoan parasite Trypanosoma cruzi. DFT calculations supported the involvement of transient cationic species which resulted from the stabilization of the oxocarbenium ion through O-6 acyl group participation. This journal is
- ?ervenková ??astná, Lucie,Cu?ínová, Petra,Dra?ínsky, Martin,Hamala, Vojtěch,Karban, Jind?ich,Kurfi?t, Martin
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Read Online
- Synthesis, antitumor activity and in silico analyses of amino acid derivatives of artepillin C, drupanin and baccharin from green propolis
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Breast cancer has the highest incidence and mortality in females, while prostate cancer has the second-highest incidence in males. Studies have shown that compounds from Brazilian green propolis have antitumor activities and can selectively inhibit the AKR1C3 enzyme, overexpressed in hormone-dependent prostate and breast tumors. Thus, in an attempt to develop new cytotoxic inhibitors against these cancers, three prenylated compounds, artepillin C, drupanin and baccharin, were isolated from green propolis to synthesize new derivatives via coupling reactions with different amino acids. All obtained derivatives were submitted to antiproliferative assays against four cancer cells (MCF-7, MDA MB-231, PC-3, and DU145) and two normal cell lines (MCF-10A and PNT-2) to evaluate their cytotoxicity. In general, the best activity was observed for compound 6e, derived from drupanin, which exhibited half-maximal inhibitory concentration (IC50) of 9.6 ± 3 μM and selectivity index (SI) of 5.5 against MCF-7 cells. In silico studies demonstrated that these derivatives present coherent docking interactions and binding modes against AKR1C3, which might represent a possible mechanism of inhibition in MCF-7 cells.
- Rodrigues, Débora Munhoz,Portapilla, Gisele Bulh?es,Silva, Guilherme Martins,Duarte, Andressa,Rotta, Cristiana Gon?alez,da Silva, Carlos Henrique Tomich de Paula,de Albuquerque, Sérgio,Bastos, Jairo Kenupp,Campo, Vanessa Leiria
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- Stereoselective synthesis of natural and non-natural thomsen-nouveau antigens and hydrazide derivatives
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A selective glycosylation strategy enabling access to all stereochemical combinations of tumor associated Thomsen-nouveau (Tn) antigen, d-GalNAc-O-Ser/Thr, has been developed. The key component for selectivity is the phthalimide-protected d- or l-amino acid acceptors which allow access to α- or β-anomers in excellent yields (72-96%) and selectivity (~100%) when appropriate C-2 substitution is installed. The glycoamino acid intermediates were divergently converted to Tn-based carboxylates or to hydrazides by tandem Pd-C debenzylation followed by treatment with hydrazine hydrate or hydrazine hydrate treatment alone.
- Shaik, Ahmad Ali,Nishat, Sharmeen,Andreana, Peter R.
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p. 2582 - 2585
(2015/06/16)
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- Concise synthesis of α-methylene-β-hydroxy-γ-carboxy- γ-lactams
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A concise protocol for the synthesis of α-methylene-β-hydroxy- γ-carboxy-γ-lactams has been described via alkylation of amino acid derived iminoesters with α-bromomethylmethacrylate, followed by allylic hydroxylation. All the synthesized compounds have been evaluated for their cytotoxicity on multiple myeloma cancer cell lines.
- Tekkam, Srinivas,Johnson, Joseph L.,Jonnalagadda, Subash C.,Mereddy, Venkatram R.
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p. 955 - 958
(2013/08/23)
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- Total synthesis of pactamycin and pactamycate: A detailed account
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This article describes synthetic studies that culminated in the first total synthesis of pactamycin and pactamycate and, in parallel, the two known congeners, de-6-MSA-pactamycin and de-6-MSA-pactamycate, lacking the 6-methylsalicylyl moiety. Starting with l-threonine as a chiron, a series of stereocontrolled condensations led to a key cyclopentenone harboring a spirocyclic oxazoline. A series of systematic functionalizations led initially to the incorrect cyclopentanone epoxide, which was "inverted" under solvolytic conditions. Installation of the remaining groups and manipulation of the oxazoline eventually led to pactamycin, pactamycate, and their desalicylyl analogues.
- Hanessian, Stephen,Vakiti, Ramkrishna Reddy,Dorich, Stéphane,Banerjee, Shyamapada,Deschênes-Simard, Beno?t
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p. 9458 - 9472
(2013/01/15)
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- Influence of steric parameters on the synthesis of tetramates from α-amino-β-alkoxy-esters and Ph3PCCO
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α-Aminoesters react with Ph3PCCO in a domino addition-Wittig cyclization sequence affording enantiomerically pure tetramates. In the case of β-oxo functionalized α-aminoesters, e.g., esters of serine, threonine or β-hydroxyornithine the yields of this reaction depend heavily on the bulkiness of the β-OR group and on the configuration of β-carbon atom C-3. Smaller residues and 2R/3R-configured aminoesters give better yields. The alkoxycarbonyl group of the ester moiety and the residue on the N-atom are less important. These findings can be accounted for by assuming an early puckered transition state for the intramolecular ring-closing Wittig reaction. The addition of sub-stoichiometric amounts of benzoic acid or N-hydroxysuccinimide (for acid-sensitive compounds) is advantageous in some cases as it accelerates the formation of the intermediate amide ylides.
- Loke, Inga,Park, Natja,Kempf, Karl,Jagusch, Carsten,Schobert, Rainer,Laschat, Sabine
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supporting information; experimental part
p. 697 - 704
(2012/01/05)
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- Design, synthesis and the effect of 1,2,3-triazole sialylmimetic neoglycoconjugates on Trypanosoma cruzi and its cell surface trans-sialidase
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This work describes the synthesis of a series of sialylmimetic neoglycoconjugates represented by 1,4-disubstituted 1,2,3-triazole-sialic acid derivatives containing galactose modified at either C-1 or C-6 positions, glucose or gulose at C-3 position, and by the amino acid derivative 1,2,3-triazole fused threonine-3-O-galactose as potential TcTS inhibitors and anti-trypanosomal agents. This series was obtained by Cu(I)-catalysed azide-alkyne cycloaddition reaction ('click chemistry') between the azido-functionalized sugars 1-N3-Gal (commercial), 6-N 3-Gal, 3-N3-Glc and 3-N3-Gul with the corresponding alkyne-based 2-propynyl-sialic acid, as well as by click chemistry reaction between the amino acid N3-ThrOBn with 3-O-propynyl-GalOMe. The 1,2,3-triazole linked sialic acid-6-O-galactose and the sialic acid-galactopyranoside showed high Trypanosoma cruzi trans-sialidase (TcTS) inhibitory activity at 1.0 mM (approx. 90%), whilst only the former displayed relevant trypanocidal activity (IC50 260 μM). These results highlight the 1,2,3-triazole linked sialic acid-6-O-galactose as a prototype for further design of new neoglycoconjugates against Chagas' disease.
- Campo, Vanessa L.,Sesti-Costa, Renata,Carneiro, Zumira A.,Silva, Jo?o S.,Schenkman, Sergio,Carvalho, Ivone
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experimental part
p. 145 - 156
(2012/02/15)
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- Total synthesis of pactamycin
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Lest we forget: 50 years after pactamycin was first isolated from a fermentation broth of Streptomyces pactum var pactum, this highly functionalized aminocyclopentitol natural product has finally succumbed to total synthesis. The modular and stereocontrolled introduction of functional groups should lead to the synthesis of less toxic congeners that maintain the antibacterial and cytotoxic activities. Copyright
- Hanessian, Stephen,Vakiti, Ramkrishna Reddy,Dorich, Stephane,Banerjee, Shyamapada,Lecomte, Fabien,DelValle, Juan R.,Zhang, Jianbin,Deschenes-Simard, Benoait
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supporting information; experimental part
p. 3497 - 3500
(2011/05/12)
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- Serine and threonine Schiff base esters react with β-anomeric peracetates in the presence of BF3·Et2O to produce β-glycosides
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Improved procedures are reported for the glycosylation of L-serine and L-threonine utilizing activated Schiff base glycosyl acceptors, which are less expensive and more efficient alternatives to published methods. L-serine or L-threonine benzyl ester hydrochloride salts were reacted with the diarylketimine bis-(4-methoxyphenyl)-methanimine in CH3CN at rt to form the more nucleophilic Schiff bases 3a and 3b in excellent yield. These Schiff bases exhibited ring-chain tautomerism in CDCl3 as shown by 1H NMR. Schiff bases 3a and 3b, acting as glycosyl acceptors, reacted at rt with simple sugar peracetate donors with BF3·OEt 2 promotion to provide the corresponding L-serine and L-threonine O-linked glycosides in excellent yields and purities. The dipeptide ester Schiff base Ar2C = N-Ser-Val-OCH3 3e also reacted to provide β-glycosides in excellent yields, and without epimerization. With microwave irradiation the reactions were complete in 2 to 5 min. To investigate this reaction further, classical AgOTf-promoted Koenigs-Knorr reaction of D-glucopyranosyl, lactosyl, and maltosyl bromides were examined, providing the β-glycosides with yields ranging from 35% to 68%. The difference in reactivity between α- and β-carbohydrate peracetate donors was remarkable. The less configurationally stable D-xylopyranosyl tetra-acetate (a pentose) showed no selectivity (αvsβ-configuration) toward the Schiff bases. Copyright Taylor & Francis Group, LLC.
- Keyari, Charles M.,Polt, Robin
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experimental part
p. 181 - 206
(2011/04/23)
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- NOVEL PHENYLPYRROLE DERIVATIVE
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The present invention relates to a compound or a pharmacologically acceptable salt thereof having superior glucokinase activating activity, and is a compound represented by general formula (I), or pharmacologically acceptable salt thereof: [wherein, A represents, for example, an oxygen atom or sulfur atom, R1 represents, for example, a C1-C6 alkyl group, a C1-C6 alkoxy group or a C1-C6 halogenated alkyl group, A and R1 together with the carbon atom bonded thereto form a heterocyclic group that may be substituted with 1 to 3 group(s) independently selected from Substituent Group α, R2 represents a phenyl group that may be substituted with 1 to 5 group(s) independently selected from Substituent Group α or a heterocyclic group that may be substituted with 1 to 3 group(s) independently selected from Substituent Group α, R3 represents a hydroxy group or a C1-C6 alkoxy group, and Substituent Group α consists of, for example, a halogen atom, a C1-C6 alkyl group, a C1-C6 alkyl group substituted with 1 or 2 hydroxy group(s), a C1-C6 alkylsulfonyl group, and a group represented by the formula -V-NR5R6 (wherein, V represents a carbonyl group or a sulfonyl group, and R5 and R6 may be the same or different and respectively represent a hydrogen atom or a C1-C6 alkyl group, or R5 and R6 together with the nitrogen atom bonded thereto form a 4- to 6-membered saturated heterocycle that may be substituted with 1 or 2 group(s) independently selected from a C1-C6 alkyl group and a hydroxy group, and the 4- to 6-membered saturated heterocycle may further contain one oxygen atom or nitrogen atom)].
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Page/Page column 136; 137
(2010/11/03)
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- A class of novel conjugates of substituted purine and Gly-AA-OBzl: Synthesis and evaluation of orally analgesic activity
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Aimed at the chemotherapy of chronic pain two kinds of analgesic pharmacophores, substituted purine and Gly-AA-OBzl, were coupled via a five-step-reaction procedure and 19 novel conjugates N-[2-chloro-9- (tetrahydropyran-2-yl)-9H-purin-6-yl]-N-cyclopropylglycylamino acid benzylesters were provided. On mouse-tail flick model their in vivo analgesic activities were assayed. The results indicate that introducing Gly-OC2H 5 into the 6-position of the substituted purine leads to ambiguous increase of the analgesic activity, while introducing Gly-AA-OBzl into this position leads to significant increase of the analgesic activity.
- Kang, Guifeng,Zhao, Ming,Zhang, Xiaoyi,Peng, Li,Li, Chunbo,Mao, Wei,Ye, Weidong,Peng, Shiqi
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supporting information; experimental part
p. 6157 - 6160
(2010/12/19)
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- Synthesis and cytotoxic activities of β-carboline amino acid ester conjugates
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β-Carboline represents a class of compounds with potent anti-tumor activity by intercalating with DNA. To further enhance the cytotoxic potency and bioavailability of β-carboline, a series of novel β-carboline amino acid ester conjugates were designed and synthesized, and the cytotoxic activities of these compounds were tested using a panel of human tumor cell lines. In addition, the membrane permeability of these compounds was evaluated in vitro using a Caco-2 cell monolayer model. The β-carboline amino acid ester conjugates demonstrated improved cytotoxic activity compared to the parental β-carbolines. In particular, the Lys/Arg conjugates were the most potent analogs with an IC50 value of 4 and 1 μM against human cervical carcinoma cells. The low interaction energy of Arg conjugate based on molecular modeling may contribute to its enhanced cytotoxicity. Taken together, this study provided new insights into structure-activity relationships in the β-carboline amino acid ester conjugates and identified the β-carboline Lys/Arg conjugates as promising lead compounds for further in vivo biological and molecular evaluation.
- Zhao, Ming,Bi, Lanrong,Wang, Wei,Wang, Chao,Baudy-Floc'h, Michele,Ju, Jingfang,Peng, Shiqi
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p. 6998 - 7010
(2007/10/03)
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