Wang Resin (wang + resin)

Distribution by Scientific Domains

Selected Abstracts

Synthesis of tritium labelled delta sleep-inducing peptide

Matthieu Giraud
Abstract The ,,, -dehydro precursor of the delta sleep-inducing peptide (DSIP) for tritiation was prepared prior to tritiation using a 3+6 fragment coupling strategy on a solid support. The first fragment, ,,, -dehydrotripeptide, was prepared in solution in five steps in 79% overall yield while the second fragment was obtained by a step by step peptide synthesis on a Wang resin using an Fmoc strategy. The ,,, -dehydrotripeptide was coupled to the fragment linked to the resin, followed by a deprotection/cleavage step to yield the ,,, -dehydro-DSIP, 7. Catalytic reduction of unsaturated DSIP using tritium gas and palladium oxide as catalyst gave [3H]DSIP having a specific activity of 1.184 TBq/mmol(32 Ci/mmol). Copyright © 2001 John Wiley & Sons, Ltd. [source]

Chemistry of ,-hydroxymethylserine: problems and solutions,

Marcin Stasiak
Abstract Further improvements related to the synthesis of peptides containing HmS are presented. Efficient synthetic protocols have been developed to synthesize "difficult" sequences containing a C -terminal HmS residue, MeA,HmS or consecutive HmS. Preparative methods for orthogonal N - and/or C -protected HmS(Ipr) derivatives are described. Their compatibility with standard solution or solid-phase peptide chemistry protocols allows synthetic flexibility toward HmS-containing peptides. In the synthesis of the sterically hindered dipeptides with the C -terminal HmS(Ipr) residue, HATU proves the highest efficiency, as compared with the fluoride and PyBroP/DMAP coupling methods. The HATU method also outperforms the fluoride activation in the solid-phase assembly of HmS homosequence. Specific protocols are described to overcome an undesired cyclization to diketopiperazines that occurs during the removal of Fmoc from dipeptides with the C -terminal HmS(Ipr) or HmS residues, thus precluding their C , N elongation. The successful protocols involve: (i) the 2 + 1 condensation using mixed anhydride activation yielding the desired product with the highest optical integrity or (ii) use of the 2-chlorotrityl resin as a solid support sterically suppressing the undesired cleavage due to diketopiperazine formation. The latter approach allows the mild conditions of peptide cleavage from solid support, preserving the isopropylidene protection and minimizing the undesired N , O -acyl migration that was observed under prolonged acid treatment used for cleaving the HmS peptide from the Wang resin. Copyright © 2008 European Peptide Society and John Wiley & Sons, Ltd. [source]

Comparative evaluation of four trityl-type amidomethyl polystyrene resins in Fmoc solid phase peptide synthesis

Christos Zikos
Abstract Four trityl-type (i.e. non-substituted trityl-, o-Cl-trityl-, o-F-trityl- and p-CN-trityl-) amidomethyl polystyrene resins were evaluated comparatively, in terms of the stability of the trityl-ester bond in slightly acidic dichloromethane solutions, and the p-CN-trityl-amidomethyl polystyrene resin was found to be the most stable of them. The above resins were applied, in parallel with Wang benzyl-type resin, well known for its stability in mild acidic conditions, to the Fmoc solid phase synthesis of the 43-amino acid residue long bioactive peptide thymosin beta-4. Independent of their differences in acid sensitivity, the resins seemed to function equally well under the conditions used, since pure thymosin beta-4 was obtained with a final yield of approximately 30% from each resin. The trityl-type amidomethyl polystyrene resins were also applied, in parallel with the Wang resin, to the Fmoc solid phase synthesis of a bioactive peptide containing proline at its C -terminus, i.e. the N -terminal tetrapeptide of thymosin beta-4, AcSDKP. In this case, the best yield (87%) was obtained with the o-Cl-trityl-amidomethyl polystyrene resin, which may be the resin of choice, of those studied, for the Fmoc solid phase peptide synthesis. Copyright © 2003 European Peptide Society and John Wiley & Sons, Ltd. [source]

Practical syntheses of [1,3,5]-triazine dendritic molecules on solid supports

Suzanne J. Dilly
Abstract A practical and divergent synthesis of supported [1,3,5]-triazine dendritic molecules on Wang resin, PEGA resin, SynPhase‘ Lanterns, and silica gel is described. The alkylamine linkers used allow derivatization with functionality for both synthetic (e.g., supported reagent and scavenger activity) and chemical biology applications. The use of supported intermediates allows differentiation of symmetric linkers without the need for protecting group chemistry. The synthetic route uses inexpensive, readily available starting materials in a straightforward and scaleable strategy. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2248,2259, 2006 [source]

Rapid Screening of New Polymer-Supported Palladium (II) Bis(3,4,5,6-tetrahydropyrimidin-2-ylidenes),

Monika Mayr
Abstract Summary: The synthesis of two 1,3-diaryl-3,4,5,6-tetrahydropyrimidin-2-ylidene-based N -heterocyclic carbene- (NHC) derived palladium complexes, Pd(5-hydroxy-1,3-bis-(2,4,6-trimethylphenyl)-3,4,5,6-tetrahydropyrimidin-2-ylidene) (Ag2Br2Cl4) (10) and Pd(5-(bicyclo[2.2.1]hept-5-ene-2-carbonyloxy)-1,3-bis-(2,4,6-trimethylphenyl)-3,4,5,6-tetrahydropyrimidin-2-ylidene) (Ag2Br2Cl4) (11) is described. 10 was supported on a PS-DVB and a Wang resin, respectively, to yield catalysts 12 and 13, while 11 was used for the synthesis of a ring-opening metathesis precipitation polymerization-derived support 14. All supports were tested for their activity in Heck-type reactions using a combinatorial approach. Structure of polymer supported Pd-catalysts. [source]

Synthesis of cyclooctapeptides: constraints analogues of the peptidic neurotoxin, ,-agatoxine IVB,an experimental point of view

Ewelina Minta
Abstract ,-AGA IVB is an important lead structure when considering the design of effectors of glutamate release inducting P/Q-type calcium channels. The best route to achieve the analogues possessing the three-dimensional arrangement corresponding to the native binding loop was the introduction of constraint by ring formation via side chain to side chain lactamization for suitably protected Lys and Glu residues. Since tryptophane residue located at position 14 of this neuropeptide has been suggested as essential for binding, analogues in which this amino acid was replaced by aza-tryptophane and alanine were synthesized. The synthesis was carried out on various acid-labile resins (BARLOS chlorotrityl, Rink amide, PEG-based or Wang resins), by Fmoc strategy. In this paper, we describe optimization of the peptide cyclization with various protecting groups, and on resin or in solution cyclization experimental parameters. Copyright © 2007 European Peptide Society and John Wiley & Sons, Ltd. [source]