| 1. |
- Ax, Anna, et al.
(author)
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Synthesis of a small library of non-symmetric cyclic sulfamide HIV-1 protease inhibitors
- 2010
-
In: Tetrahedron. - : Elsevier BV. - 0040-4020 .- 1464-5416. ; 66:23, s. 4049-4056
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Journal article (peer-reviewed)abstract
- A set of 11 non-symmetric cyclic sulfamide HIV-1 protease inhibitors were synthesized and evaluated. The use of a key microwave-assisted silver(I) oxide mediated selective mono N-benzylation reaction enabled fast and straightforward synthesis. The K-i values of the new inhibitors ranged between 0.28 mu M and >20 mu M.
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| 2. |
- Barbion, Julien, et al.
(author)
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Stereoselective functionalization of pyrrolidinone moiety towards the synthesis of salinosporamide A
- 2012
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In: Tetrahedron. - : Elsevier BV. - 0040-4020 .- 1464-5416. ; 68:32, s. 6504-6512
-
Journal article (peer-reviewed)abstract
- An important feature of the synthesis of salinosporamide A. a potent proteasome inhibitor, is the establishment of the quaternary stereocenter at C3. A new route has been developed based on the methylation of a functionalized pyrrolidinone. Direct methylation reaction led to the unwanted diastereomer: however, by means of a Corey-Chaykovsky reaction followed by LiAlH4 epoxide opening, the desired alcohol was obtained. The pyrrolidinone was elaborated through a key allylation reaction between a tertiary allyltitanium reagent and an aldehyde bearing a spiroketal moiety in alpha-position.
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| 3. |
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| 4. |
- Blach, Philippe, et al.
(author)
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Recyclable process for sustainable adipic acid production in microemulsions
- 2010
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In: Tetrahedron. - : Elsevier BV. - 0040-4020. ; 66:35, s. 7124-7128
-
Journal article (peer-reviewed)abstract
- Adipic acid is an important industrial intermediate for the manufacture of nylon-6,6. We propose a recyclable and environmentally friendly process for the oxidation of cyclohexene by hydrogen peroxide in microemulsions. These organized nano-structured media have been formulated in using the molecular economy principle. The main interests of the present work are the easy recovery of pure adipic acid and the reuse of the reaction media, what are promising for developing a future green industrial process.
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| 5. |
- Cai, Shengyun, et al.
(author)
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Photo-stable substituted dihydroindolo[2,3-b]carbazole-based organic dyes : tuning the photovoltaic properties by optimizing the pi structure for panchromatic DSSCs
- 2014
-
In: Tetrahedron. - : Elsevier BV. - 0040-4020 .- 1464-5416. ; 70:43, s. 8122-8128
-
Journal article (peer-reviewed)abstract
- Three dihydroindolo[2,3-b]carbazole (DDC) donor based organic dyes (DDC6-DDC8) with long conjugated systems were successfully synthesized and characterized by optical, electrochemical, computational analysis, and photovoltaic methods. It was found that the elongated pi system as well as the high molar extinction coefficients (4.2-5.3 M-1 cm(-1)) sufficiently reinforced the light harvesting ability with the IPCE response of one dye DDC8 extended to 850 nm, which resulted in large J(sc) of these dyes based devices (high as 16.41 mA cm(-2)). The attached alkyl chains suppress the dark current to some extent, resulting the DDC6 and DDC7 devices in high V-oc, while DDC8 displayed low V-oc, because BTD in DDC8 could attract the iodine ion, which could accelerate the charge recombination. Among the three dyes, DDC7 displayed the best performance with an eta value 6.53% under 4 mu m thick scattering layer (condition 1+1), which was boosted to 7.49% under 8 mu m thick scattering layer (condition 1+2). The photo-stability measurements indicated that all the three dyes are fairly photo-stable.
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| 6. |
- Claerhout, Stijn, et al.
(author)
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Synthesis of functionalized furopyrazines as restricted dipeptidomimetics
- 2012
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In: Tetrahedron. - : Elsevier BV. - 0040-4020 .- 1464-5416. ; 68:14, s. 3019-3029
-
Journal article (peer-reviewed)abstract
- Herein, an efficient synthetic approach to a furopyrazine scaffold with four points of diversity, starting from 2(1H)-pyrazinones, with dipeptomimetic properties, is presented. R-groups corresponding to amino acid side chains were introduced during the 2(1H)-pyrazinone and subsequent furopyrazine formation. The furopyrazine scaffold was further functionalized with an amino- and a carboxy-terminus resulting in a conformationally restricted dipeptidomimetic scaffold. The carboxy-terminus was introduced via a chemoselective vinylation of the 7-position followed by oxidative cleavage, while the amino-terminus was obtained via Buchwald-Hartwig amidation of the 2-position of the scaffold. The versatility of the synthetic method was demonstrated by the synthesis of a small library of diversely substituted furopyrazines having various amino acid side chains on the four points of diversity. Evaluation with an X-ray structure of the scaffold and computational analysis supports the exploitation of the furopyrazine scaffold as a restricted dipeptide mimic, which can mimic the two central residues of a beta-turn.
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| 7. |
- Engström, Karin, et al.
(author)
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Kinetic resolution of diarylmethanols using a mutated variant of lipase CALB
- 2012
-
In: Tetrahedron. - : Elsevier BV. - 0040-4020 .- 1464-5416. ; 68:37, s. 7613-7618
-
Journal article (peer-reviewed)abstract
- An enzymatic kinetic resolution of diarylmethanols via acylation has been developed. This was achieved by the use of a mutated variant of CALB that accepts larger substrates compared to the wild type. By the use of diarylmethanols with two differently sized aryl groups, enantioselective transformations were achieved. A larger size-difference led to a higher enantioselectivity. In addition, substrates with electronically different aryl groups, such as phenyl and pyridyl, also gave an enantioselective reaction. The highest E value was observed with a substrate where steric and electronic effects were combined.
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| 8. |
- Escobar, Zilma, et al.
(author)
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Synthesis of poinsettifolin A
- 2014
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In: Tetrahedron. - : Elsevier BV. - 0040-4020. ; 70:47, s. 9052-9056
-
Journal article (peer-reviewed)abstract
- A synthesis of poinsettifolin A (1), a prenylated flavonol isolated from Dorstenia poinsettifolia, is described. Two routes starting from quercetin were explored, and 1 could be prepared if a prenyl group first was incorporated at C-6 of the protected quercetin followed by a condensation with citral at C-8. The key synthetic steps are a Mitsunobu reaction, an europium (III)-catalysed Claisen rearrangement coupled with cross-metathesis, and a benzopyran-forming geranylation. The two geranylated 3,5,3',4'-tetrahydroxyflavonols prepared, 1 and 3, were assayed for antileishmanial activity against Leishmania amazonensis and Leishmania braziliensis, and found to be active. Compound 3 showed cytotoxic activity against leukaemia and lung cancer cells while 1 lacked cytotoxicity. (C) 2014 Elsevier Ltd. All rights reserved.
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| 9. |
- Fourniere, Viviane, et al.
(author)
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Synthesis of the Lewis b pentasaccharide and a HSA-conjugate thereof
- 2010
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In: Tetrahedron. - : Elsevier BV. - 0040-4020 .- 1464-5416. ; 66:39, s. 7850-7855
-
Journal article (peer-reviewed)abstract
- Helicobacter pylori, a gastric pathogen, binds to various blood group antigens, including the Lewis types, present in the gastric tissue and a relation between the presentation of the ligands and the overall strength of binding has been assumed. Synthetic Lewis b tetra- and hexasaccharide conjugates are available but not the analogous pentasaccharide. An efficient synthesis of the amino spacer equipped Lewis b pentasaccharide, 3-aminopropyl alpha-L-fucopyranosyl-(1 -> 2)-beta-D-galactopyranosyl-(1 3)-[alpha-L-fucopyranosyl-(1 -> 4)]-2-acetamido-2-deoxy-beta-D-glucopyranosyl-(1 -> 3)-beta-D-galactopyranoside, is presented to enable further investigation of the carbohydrate recognition process of H. pylori.
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| 10. |
- Fridén-Saxin, Maria, 1979, et al.
(author)
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Proline-mediated formation of novel chroman-4-one tetrahydropyrimidines
- 2012
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In: Tetrahedron. - : Elsevier BV. - 0040-4020. ; 68:35, s. 7035-7040
-
Journal article (peer-reviewed)abstract
- Novel tricyclic N-benzylated chroman-4-one tetrahydropyrimidine derivatives have been prepared through a multi-component reaction between various 2-substituted chroman-4-one derivatives, N-methylenebenzylamine and a catalytic amount of proline under mild reaction conditions. The tricyclic structure of 1a was determined by NMR spectroscopy and confirmed by X-ray crystallography. An additional product, 2a, was isolated from the reaction mixture and its structure and conformation were determined by a combination of theoretical (Monte Carlo conformational search) and NMR-based (NOE and (3)J(HH) couplings) conformational analysis. The NMR analysis revealed one preferred geometry for 1a and 2a in CHCl3 solution. (C) 2012 Elsevier Ltd. All rights reserved.
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| 11. |
- Fyrner, Timmy, et al.
(author)
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Synthesis of tri-, penta-, and hepta-saccharides, functionalized with Orthogonally N-Protected Amino residues at the reducing and non-reducing ends
- 2012
-
In: Tetrahedron. - : Elsevier BV. - 0040-4020 .- 1464-5416. ; 68:33, s. 6712-6720
-
Journal article (peer-reviewed)abstract
- The synthesis of four bifunctionalized orthogonally N-protected oligosaccharides derived from lactose and mannose, intended as cross-linking derivatives, is described. The amino sugar at the non-reducing end is derivatized with an N-Boc-protected glycine moiety, and further connected to either a mannose (1→6) disaccharide or (1→3) lactose units (one, two or three) resulting in tri-, penta-, or heptasaccharides. All of the synthesized oligosaccharides have an Nbenzyloxycarbonyl-aminoethyl residue at the reducing end. The fully orthogonal N-Boc/N-Cbz protection group pattern enables further conjugation/derivatization and results in a hydrophilic cross-linking molecule. It was found that the order of the final synthetic steps were crucial to avoid acyl migration. A suitable amide coupling protocol has been applied to introduce the NBoc-protected glycine moiety in alcoholic solvent. The synthesized oligosaccharides will provide a model system to investigate the influence of length, structure and flexibility. The function of the cross-linked substituents thereby provide valuable insights into the role as a spacer molecule.
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| 12. |
- Hammer, Stephan C., et al.
(author)
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Stereoselective Friedel-Crafts alkylation catalyzed by squalene hopene cyclases
- 2012
-
In: Tetrahedron. - : Elsevier Ltd.. - 0040-4020 .- 1464-5416. ; 68:Copyright (C) 2013 American Chemical Society (ACS). All Rights Reserved., s. 7624-7629
-
Journal article (peer-reviewed)abstract
- In org. synthesis the Friedel-Crafts alkylation is of eminent importance, as it is a key reaction in many synthetic routes. A general access to enzymic Friedel-Crafts alkylations would be very beneficial due to the high selectivity of biocatalysts. We used designed polyprenyl Ph ethers to specifically address this reaction by using squalene hopene cyclases as catalysts. Polycyclic products with arom. rings constituting important biol. active compds. were obtained. Our results demonstrate that squalene hopene cyclases can be utilized for Friedel-Crafts alkylations and reveal the potential of these enzymes for chiral Bronsted acid catalysis.
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| 13. |
- Hao, Yan, et al.
(author)
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Engineering of highly efficient tetrahydroquinoline sensitizers for dye-sensitized solar cells
- 2012
-
In: Tetrahedron. - : Elsevier. - 0040-4020 .- 1464-5416. ; 68:2, s. 552-558
-
Journal article (peer-reviewed)abstract
- Four novel tetrahydroquinoline dyes by inserting isophorone and/or thiophene moieties as pi bridge between the electron donating unit of substituted tetrahydroquinoline and the electron withdrawing unit of cyano carboxylic acid have been synthesized and successfully applied to dye-sensitized solar cells. Among them, DSCs sensitized by HYTIC, which shows the simplest molecular structure, exhibit improved efficiency of 7.0%. This by now is the highest efficiency for the reported tetrahydroquinoline sensitizers and comparable to the performance of N719-sensitized solar cells under the conditions employed here. (C) 2011 Elsevier Ltd. All rights reserved.
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| 14. |
- Hertzberg, Robin, et al.
(author)
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Enantioenriched ω-bromocyanohydrin derivatives. Improved selectivity by combination of two chiral catalysts
- 2012
-
In: Tetrahedron. - : Elsevier BV. - 0040-4020 .- 1464-5416. ; 68:37, s. 7680-7684
-
Journal article (peer-reviewed)abstract
- Highly enantioenriched (R)-4-bromo-1-cyanobutyl acetate and (R)-5-bromo-1-cyanopentyl acetate were prepared by acetylcyanation of 4-bromobutanal and 5-bromopentanal, respectively, catalyzed by (S,S)-[(4,6-bis(t-butyl)salen)Ti(Ό-O)] 2 and triethylamine followed by enzymatic hydrolysis of the minor enantiomer. A cyclic procedure employing the same two chiral catalysts provided inferior results due to a slowly reached steady state and, in reactions with the former substrate, to ring-closure of the free cyanohydrin formed as an intermediate in the reaction. Hydrolysis of the acylated cyanohydrins followed by AgClO 4-promoted cyclization provided (R)-2-cyanotetrahydrofuran and (R)-2-cyanotetrahydropyran in essentially enantiopure form.
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| 15. |
- Jalalian, Nazli, 1982-, et al.
(author)
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Design and asymmetric synthesis of chiral diaryliodonium salts
- 2010
-
In: Tetrahedron. - : Elsevier BV. - 0040-4020 .- 1464-5416. ; 66:31, s. 5793-5800
-
Journal article (peer-reviewed)abstract
- The application of chiral hypervalent iodine reagents in asymmetric synthesis is highly desirable, as the reagents are metal-free, environmentally benign and employed under mild conditions. Three chiral diaryliodonium salts have been designed to provide chemoselectivity and asymmetric induction in asymmetric alpha-phenylation of carbonyl compounds. The synthetic routes to the selected targets are detailed herein, together with a structural investigation into the diastereoselectivity of the alkylation process.
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| 16. |
- Lahmann, Martina, et al.
(author)
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Transformations of chromanol and tocopherol and synthesis of ascorbate conjugates
- 2011
-
In: Tetrahedron. - : Elsevier BV. - 0040-4020 .- 1464-5416. ; 67:9, s. 1654-1664
-
Journal article (peer-reviewed)abstract
- alpha-Tocopherol and as a model compound pentamethylchromanol could be transferred into simple and more complex 5a-ether derivatives including galactopyranose as well as ascorbic acid conjugates. Following elaboration of a glucopyranoside spacer element this could be used for tethering the vitamin E and the vitamin C components to give novel conjugates for subsequent biostudies concerning their proposed synergism of antioxidant properties in tissues.
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| 17. |
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| 18. |
- Lega, Matteo, et al.
(author)
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Expanding the scope of the elpaN-type library : glucose-derived bis(pyridine-2-carboxamide) ligands (elpaN-Py) for molybdenum-catalyzed asymmetric allylic alkylations
- 2013
-
In: Tetrahedron. - : Elsevier BV. - 0040-4020 .- 1464-5416. ; 69:20, s. 4061-4065
-
Journal article (peer-reviewed)abstract
- The elpaN-Py family of ligands, which represents a subset of the elpaN-type library based on a-glucose, is described. The ligands are structural analogs of the privileged bis(pyridine-2-carboxamides) derived from trans-1,2-diaminocyclohexane, and differ for the type of substitution in the coordinating functions present in positions 1 and 2. Their ability to induce high enantioselectivity in asymmetric allylic alkylations promoted by molybdenum under microwave irradiation has been successfully demonstrated, starting from both a linear (ee up to 99%) and a branched substrate (ee up to 96%). The multifunctional nature of the sugar scaffold was exploited for the preparation of a polar ligand, through deprotection of the hydroxyl groups in positions 3, 4 and 6. In this version, it was possible to verify the performance in catalysis in alternative solvents, such as ionic liquids and water.
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| 19. |
- Maldonado, Matias Funes, et al.
(author)
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Synthesis and arylation of unprotected sulfonimidamides
- 2012
-
In: Tetrahedron. - : Elsevier BV. - 0040-4020 .- 1464-5416. ; 68:36, s. 7456-7462
-
Journal article (peer-reviewed)abstract
- Herein we evaluate different methodologies for the synthesis of unprotected sulfonimidamides. Three different procedures that allow orthogonal deprotection of the imine nitrogen under acidic, nucleophilic, and basic conditions were established. Moreover, we present a highly efficient methodology for functionalization of the imine nitrogen through Pd-catalyzed C-N arylation. RuPhos ligand was shown to allow short reaction time, excellent yields, and allowed coupling of both aryl halides and heteroaryl bromides.
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| 20. |
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| 21. |
- Mesas-Sanchez, Laura, et al.
(author)
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Kinetic resolution of 2-hydroxy-2-aryl-ethylphosphonates by a non-enzymatic acylation catalyst
- 2014
-
In: Tetrahedron. - : Elsevier. - 0040-4020 .- 1464-5416. ; 70:24, s. 3807-3811
-
Journal article (peer-reviewed)abstract
- Optically pure hydroxyphosphonates are widely used as derivatizable compounds that can be incorporated into a variety of synthetic strategies for the preparation of other high value organic products. A non-enzymatic kinetic resolution procedure to obtain chiral 2-hydroxy-2-arylethylphosphonates from the easily available racemic counterparts is described. A range of 2-hydroxy-2-arylethylphosphonates was efficiently resolved employing a planar-chiral DMAP derived catalyst with good selectivities (up to S=68). The chiral hydroxyphosphonates were isolated in good yields and high enantiomeric excess (>94% ee).
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| 22. |
- Mesas-Sánchez, Laura, et al.
(author)
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Non-enzymatic kinetic resolution of 1,2-azidoalcohols using a planar-chiral DMAP derivative catalyst
- 2013
-
In: Tetrahedron. - : Elsevier BV. - 0040-4020 .- 1464-5416. ; 69:2, s. 753-757
-
Journal article (peer-reviewed)abstract
- Optically pure 1,2-azidoalcohols are widely used as precursors for other high value organic products. A non-enzymatic kinetic resolution procedure for the stereoselective synthesis of chiral 1,2-azidoalcohols from the readily available racemic counterparts has been developed, employing a planar-chiral DMAP derivative catalyst. Following this procedure, a range of aromatic 1,2-azidoalcohols was obtained in good selectivities (up to S=45) and high enantiomeric excess (up to 99% ee).
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| 23. |
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| 24. |
- Napolitano, C., et al.
(author)
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Synthesis, kinase activity and molecular modeling of a resorcylic acid lactone incorporating an amide and a trans-enone in the macrocycle
- 2012
-
In: Tetrahedron. - : Elsevier BV. - 0040-4020 .- 1464-5416. ; 68:27-28, s. 5533-5540
-
Journal article (peer-reviewed)abstract
- Details for the synthesis of a resorcylic acid lactone (RAL) incorporating a trans-enone and an amide in the macrocyclic ring are provided herein. The sequence included the assembly of three fragments by esterification, olefination, and lactamization. The RAL with the lactam was less potent as an inhibitor of kinases than other RALs investigated. The biological results were rationalized by docking and molecular dynamics simulations of the lactam bound to human ERK2 and comparison with hypothemycin. (c) 2012 Elsevier Ltd. All rights reserved.
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| 25. |
- Nilsson, Jakob, et al.
(author)
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Lactam analogues of galiellalactone
- 2012
-
In: Tetrahedron. - : Elsevier BV. - 0040-4020. ; 68:16, s. 3336-3341
-
Journal article (peer-reviewed)abstract
- A synthetic route to lactam analogues of the fungal STAT3 inhibitor galiellalactone is presented. The synthesis involves a one-pot tosylamide amide coupling/intramolecular Michael addition and an introduction of an alpha,beta-unsaturation, regioselectively directed by the tosyl functionality. An iodolactonization of the octahydroindolizine 9 and a re-opening of the lactone were employed for introducing an iodo substituent, facilitating the preparation of 8-substituted analogues (e.g., 4) using a Suzuki cross-coupling. (C) 2012 Elsevier Ltd. All rights reserved.
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| 26. |
- Nkambule, Comfort M., et al.
(author)
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Efficient regioselective protection of myo-inositol via migration facile protecting group
- 2011
-
In: Tetrahedron. - : Elsevier BV. - 0040-4020 .- 1464-5416. ; 67:3, s. 618-623
-
Journal article (peer-reviewed)abstract
- A cis-1,2-cyclohexanediol, 1,4,5,6-tetra-O-benzyl-myo-inositol, was selectively protected at the axial C2-hydroxyl via acid-mediated rearrangement of the corresponding 1,2-orthoacetate, or via the base-induced migration of a protecting group that had previously been easily installed with complete regioselectivity at the adjacent equatorial hydroxyl. Esters 4a-6a were synthesized in high yields (75-82%) while sulfonate 7a and silyl ether 8a were obtained in 85 and 31% yields, respectively. The migration of the esters induced by DBU results in equilibrium between regioisomers favouring the C2 protected isomer, but NaH induced migration of sulfonyl and silyl groups results in complete migration from equatorial to axial hydroxyl groups.
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| 27. |
- Norrehed, Sara, 1982-, et al.
(author)
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Conformational restriction of flexible molecules in solution by a semirigid bis-porphyrin molecular tweezer
- 2013
-
In: Tetrahedron. - : Elsevier BV. - 0040-4020 .- 1464-5416. ; 69:34, s. 7131-7138
-
Journal article (peer-reviewed)abstract
- A semirigid bis-porphyrin molecular clip with a glycoluril backbone has been synthesized. The clip provides an adaptable molecular cavity for binding of diamines. Binding constants for diamines of 104–107 M−1 are orders of magnitude higher than those for monoamines of 103 M−1, indicating a preference to bidentate binding. NMR studies confirmed that binding of bidentate guests occurs inside the clip. Short- and medium-size acyclic molecular guests are locked into a single, extended conformation, and also guests with longer flexible chains exhibit considerably less conformational mobility than when free in solution. The size of the cavity adapts to the guest size, as indicated by modelling studies and self diffusion constants of the complexes.
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| 28. |
- Pettersson, Birgitta, et al.
(author)
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Synthetic studies towards 1,5-benzodiazocines
- 2013
-
In: Tetrahedron. - : Elsevier BV. - 0040-4020 .- 1464-5416. ; 69:12, s. 2647-2654
-
Journal article (peer-reviewed)abstract
- Anthranilonitrile reacted with phenylmagnesium bromide to yield a dianion, which when heated (similar to 120 degrees C) yielded the condensation product 2-(2-aminophenyl)-2,4-dipheny1-1,2-dihydroquinazoline 8. This heterocycle, when treated with palladium acetate, was converted into 6,12-diphenyldibenzo[b,f][1,5] diazocine 9. Methylmagnesium bromide and anthranilonitrile, under similar conditions directly gave a nitrogen-bridged diazocine, whose structure was determined by X-ray crystallography and also proven to be an analogue of Troger's base. Acid-induced condensation of 2-amino-3-methoxybenzaldehyde gave the trimeric product 45 rather than a dibenzo[b,f][1,5]diazocine.
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| 29. |
- Redwan, Itedale Namro, 1981, et al.
(author)
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Investigation, optimization and synthesis of sulfamoyloxy-linked aminoacyl-AMP analogues
- 2012
-
In: Tetrahedron. - : Elsevier BV. - 0040-4020 .- 1464-5416. ; 68, s. 1507-1514
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Journal article (peer-reviewed)abstract
- Aminoacyl-tRNA synthetases (aaRSs) constitute a family of enzymes that transfer amino acids to their corresponding tRNA molecules to form aminoacyl-tRNAs and have been validated as potential drug targets. Sulfamoyloxy-linked aminoacyl-AMP analogues are potent inhibitors of aaRSs. In this article, we report the synthesis of several new sulfamoyl analogues of aa-AMP that up to now have been difficult or even impossible to prepare with current synthetic strategies. The developed synthetic strategy relies on performing the synthesis under neutral conditions followed by global deprotection using catalytic hydrogenation affording the desired 5′-O-(N-aminoacyl)sulfamoyladenosine compounds. © 2011 Elsevier Ltd. All rights reserved.
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| 30. |
- Redwan, Itedale Namro, 1981, et al.
(author)
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Synthesis and photophysical characterization of 1-and 4-(purinyl) triazoles
- 2013
-
In: Tetrahedron. - : Elsevier BV. - 0040-4020. ; 69:42, s. 8857-8864
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Journal article (peer-reviewed)abstract
- Fluorescent adenine mimetics are useful tools for studying DNA, RNA and enzyme functions. Herein we describe the synthesis of eight 1-(purinyl)triazoles and two 4-(purinyl)triazoles utilizing the 1,4-regioselective copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction as the key step. The fluorescence properties of five of the synthesized 1-(purinyl)triazoles are also presented. The five measured compounds displayed low quantum yields. The results, when compared to previously published data, suggest a high influence of the substitution pattern of the triazole on the fluorescence properties.
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| 31. |
- Suresh, Surisetti, et al.
(author)
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Synthesis of antimalarial compounds fosmidomycin and FR900098 through N- or P-alkylation reactions
- 2013
-
In: Tetrahedron. - : Elsevier BV. - 0040-4020 .- 1464-5416. ; 69:3, s. 1183-1188
-
Journal article (peer-reviewed)abstract
- Two straightforward and convenient routes for the synthesis of the antimalarial agents FR900098 and fosmidomycin are described. In the key steps N- or P-alkylation reactions are used. The best overall yields of FR900098 and fosmidomycin in 15 mmol scale are 83% and 68%, respectively. These routes utilize readily available materials and avoid harsh conditions.
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| 32. |
- Ying, Weijiang, et al.
(author)
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Synthesis and photovoltaic properties of new [1,2,5]thiadiazolo[3,4-c]pyridine-based organic Broadly absorbing sensitizers for dye-sensitized solar cells
- 2014
-
In: Tetrahedron. - : Elsevier BV. - 0040-4020 .- 1464-5416. ; 70:25, s. 3901-3908
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Journal article (peer-reviewed)abstract
- In this paper, by introducing [1,2,5]thiadiazolo[3,4-c]pyridine (PT) as an auxiliary acceptor into the molecular design of organic sensitizers, we have synthesized four new dyes (PT1 -P14) for dye-sensitized solar cells (DSSCs) with triphenylamine or N,N-diphenylthiophen-2-amine as the donor units and thiophene or benzene as the pi-bridges, respectively. All the structures, optical and electrochemical properties were fully characterized. Nanocrystalline TiO2 dye-sensitized solar cells were also fabricated using these dyes. Among them, PT2-based DSSCs showed the highest overall conversion efficiency of 6.11% with V-oc=668 mV, J(sc)=12.61 mA cm(-2) and a fill factor (FF)=0.74 after a chenodeoxycholic acid (CDCA) treatment under standard illumination condition (100 mW cm(-2) simulated AM 1.5 solar light).
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| 33. |
- Zhang, Qi, et al.
(author)
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Synthesis of C-11 linked active ester derivatives of vitamin D3 and their conjugations to 42-residue helix–loop–helix peptides
- 2010
-
In: Tetrahedron. - : Elsevier. - 0040-4020 .- 1464-5416. ; 66:25, s. 4577-4586
-
Journal article (peer-reviewed)abstract
- Derivatives of vitamin D3 carrying an 8-carbon linker at C-11 terminating in an active ester were synthesized from commercial vitamin D3 using a disassembly- ereassembly strategy. Vitamin D3 was cleaved at the C6-C7 double bond and the ‘upper’ fragment was converted, via a series of reactions, to derivatives substituted at C-11 with an 8-carbon linker terminating in an ethyl ester. Reassembly with modified ‘lower’ fragments using Horner-Wittig olefination followed by linker ester hydrolysis and reesterification with p-nitrophenol gave C-11 substituted p-nitrophenyl esters. These vitamin D derivatives were conjugated to 42-amino acid helix-loop-helix peptides by reaction of their p-nitrophenyl esters with lysyl side-chain amino groups on the peptides. The vitamin D-peptide conjugates, being potential specific binder candidates forvitamin D-binding protein, were characterized by mass spectroscopy and CD measurements.
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| 34. |
- Zhang, Yan, et al.
(author)
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Asymmetric synthesis of 1,3-oxathiolan-5-one derivatives through dynamic covalent kinetic resolution
- 2014
-
In: Tetrahedron. - : Elsevier BV. - 0040-4020 .- 1464-5416. ; 70:24, s. 3826-3831
-
Journal article (peer-reviewed)abstract
- The asymmetric synthesis of 1,3-oxathiolan-5-one derivatives through an enzyme-catalyzed, dynamic covalent kinetic resolution strategy is presented. Dynamic hemithioacetal formation combined with intramolecular, lipase-catalyzed lactonization resulted in good conversions with moderate to good enantiomeric excess (ee) for the final products. The process was evaluated for different lipase preparations, solvents, bases, and reaction temperatures, where lipase B from Candida antarctica (CAL-B) proved most efficient. The substrate scope was furthermore explored for a range of aldehyde structures, together with the potential access to nucleoside analog inhibitor core structures.
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| 35. |
- Zhou, Haitao, et al.
(author)
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New cyano-substituted organic dyes containing different electrophilic groups : aggregation-induced emission and large two-photon absorption cross section
- 2014
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In: Tetrahedron. - : Elsevier BV. - 0040-4020 .- 1464-5416. ; 70:39, s. 7050-7056
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Journal article (peer-reviewed)abstract
- Three aggregation-induced emission active dyes (3a-c) were synthesized and their one- and two-photon absorption properties have been investigated. They were all found to be weakly fluorescent in THF solution, while they exhibited dramatic fluorescence enhancement in water/THF mixtures. The solid fluorescence of 3a-c was recorded and their fluorescence quantum efficiency (Phi(F)) values were determined to be 8.0%, 8.1%, and 16.4%, respectively. Moreover, the two-photon absorption (2PA) cross-sections (sigma) of 3a-c were measured and 3a showed the highest value of 702 GM. The excellent aggregation-induced emission and 2PA properties provide a promising alternative for biophotonic materials.
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| 36. |
- Öberg, Christopher, et al.
(author)
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Synthesis of 3-amido-3-deoxy-beta-D-talopyranosides: all-cis-substituted pyranosides as lectin inhibitors
- 2011
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In: Tetrahedron. - : Elsevier BV. - 0040-4020. ; 67:47, s. 9164-9172
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Journal article (peer-reviewed)abstract
- 3-Deoxy-3-amino-beta-D-talopyranosides have been synthesized for the first time. The amines were obtained from galactopyranosides through 2,3-anhydrogulosides that were opened to idosides followed by an oxidation/reductive amination sequence. From the amines, 11 corresponding 3-deoxy-3-arylamido-beta-talopyranosides have been synthesized and evaluated as inhibitors against galectin-1, -2, -3, -4C, -4N, -7, -8N and -9N. The synthesized talosamides showed selectivity for Galectin-4C with three of the mono-saccharides having dissociation constants at around 100 mu M against the lectin, which is more than two orders of magnitude better than methyl beta-galactoside and significantly better than the previous best galectin-4C monosaccharide inhibitor. (C) 2011 Elsevier Ltd. All rights reserved.
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