The Experts below are selected from a list of 132 Experts worldwide ranked by ideXlab platform
Maurizio Maltese - One of the best experts on this subject based on the ideXlab platform.
-
zinc chloride homogeneous catalysis in the Tritylation of hydroxyl and amide bearing molecules
ChemInform, 2011Co-Authors: Maurizio Maltese, Maria Cecilia Vergari, Maria Pia DonzelloAbstract:A novel protocol based on the use of trityl acetate in the presence of catalytic amounts of zinc chloride is developed.
-
zinc chloride homogeneous catalysis in the Tritylation of hydroxyl and amide bearing molecules
Tetrahedron Letters, 2011Co-Authors: Maurizio Maltese, Maria Cecilia Vergari, Maria Pia DonzelloAbstract:Abstract A Tritylation protocol based on the transfer of the triphenylmethylcarbenium ion from trityl acetate to substrates having hydroxyls, in the presence of catalytic amounts of ZnCl2, is described. The advantages of this method are broad scope, mild conditions, and easy handling. The comparison with the procedure based on the use of equimolar mixture of TrCl and ZnCl2 in the presence of TEA shows that comparable results are obtained. However, only this method allows reactions of secondary or benzylic alcohols such as oxidation or formation of symmetric ethers to be suppressed. Both procedures are successfully extended to simple and substituted amides. Irrespective of its low solubility in acetonitrile, even asparagine can be directly tritylated on its amide group.
-
friedel crafts catalysts as assistants in the Tritylation of less reactive hydroxyls
ChemInform, 2010Co-Authors: Roberta Bernini, Maurizio MalteseAbstract:A simple and mild procedure is developed which can be used for base-sensitive functions such as esters and Fmoc-protected amino groups.
-
friedel crafts catalysts as assistants in the Tritylation of less reactive hydroxyls
Tetrahedron Letters, 2010Co-Authors: Roberta Bernini, Maurizio MalteseAbstract:Less reactive hydroxyls, such as those present in secondary alcohols and in some primary alcohols, phenols and carboxylic acids, were easily tritylated with the homogeneous assistance of equimolar quantities of chlorides of di- and trivalent metals in aprotic solvents. The metal ions allowed both high concentration of the effective reagent triphenylmethylcarbenium ion and mobilisation of the hydroxyl proton, thus giving rise to rapid, room temperature substitution reactions. The experimental conditions were so mild that other protected groups, such as alkyl- or trityl-protected carboxyls and (9-fluorenylmethoxycarbonyl)- or trityl-protected amino groups, remained unaffected.
Yuji Nishiuchi - One of the best experts on this subject based on the ideXlab platform.
-
regioselective formation of multiple disulfide bonds with the aid of postsynthetic s Tritylation
Organic Letters, 2015Co-Authors: Masayoshi Mochizuki, Shugo Tsuda, Kyoko Tanimura, Yuji NishiuchiAbstract:Disulfide bond formation performed in solution with the tert-butylthio (StBu) group was accomplished using a free peptide having only the sulfhydryl groups of Cys protected with the aid of postsynthetic S-Tritylation. This facilitated removal of the StBu group with subsequent disulfide formation without any difficulty. This strategy using the StBu group in combination with the widely used acetamidomethyl (Acm), 4-methylbenzyl/4-methoxybenzyl (Meb/Mob), and trityl (Trt) groups enables reliable and regioselective synthesis of multicystine peptides.
-
postsynthetic modification of unprotected peptides via s Tritylation reaction
Organic Letters, 2014Co-Authors: Masayoshi Mochizuki, Hajime Hibino, Yuji NishiuchiAbstract:Tritylation using trityl alcohol (Trt–OH) in 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) is a convenient and efficient procedure that can offer S-protection of the Cys located in fully unprotected peptides. The procedure simply requires Trt–OH and HFIP to selectively promote S-Tritylation in the presence of peptide nucleophilic functionalities.
-
Postsynthetic Modification of Unprotected Peptides via S‑Tritylation Reaction
2014Co-Authors: Masayoshi Mochizuki, Hajime Hibino, Yuji NishiuchiAbstract:Tritylation using trityl alcohol (Trt–OH) in 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) is a convenient and efficient procedure that can offer S-protection of the Cys located in fully unprotected peptides. The procedure simply requires Trt–OH and HFIP to selectively promote S-Tritylation in the presence of peptide nucleophilic functionalities
Maria Pia Donzello - One of the best experts on this subject based on the ideXlab platform.
-
zinc chloride homogeneous catalysis in the Tritylation of hydroxyl and amide bearing molecules
ChemInform, 2011Co-Authors: Maurizio Maltese, Maria Cecilia Vergari, Maria Pia DonzelloAbstract:A novel protocol based on the use of trityl acetate in the presence of catalytic amounts of zinc chloride is developed.
-
zinc chloride homogeneous catalysis in the Tritylation of hydroxyl and amide bearing molecules
Tetrahedron Letters, 2011Co-Authors: Maurizio Maltese, Maria Cecilia Vergari, Maria Pia DonzelloAbstract:Abstract A Tritylation protocol based on the transfer of the triphenylmethylcarbenium ion from trityl acetate to substrates having hydroxyls, in the presence of catalytic amounts of ZnCl2, is described. The advantages of this method are broad scope, mild conditions, and easy handling. The comparison with the procedure based on the use of equimolar mixture of TrCl and ZnCl2 in the presence of TEA shows that comparable results are obtained. However, only this method allows reactions of secondary or benzylic alcohols such as oxidation or formation of symmetric ethers to be suppressed. Both procedures are successfully extended to simple and substituted amides. Irrespective of its low solubility in acetonitrile, even asparagine can be directly tritylated on its amide group.
Masayoshi Mochizuki - One of the best experts on this subject based on the ideXlab platform.
-
regioselective formation of multiple disulfide bonds with the aid of postsynthetic s Tritylation
Organic Letters, 2015Co-Authors: Masayoshi Mochizuki, Shugo Tsuda, Kyoko Tanimura, Yuji NishiuchiAbstract:Disulfide bond formation performed in solution with the tert-butylthio (StBu) group was accomplished using a free peptide having only the sulfhydryl groups of Cys protected with the aid of postsynthetic S-Tritylation. This facilitated removal of the StBu group with subsequent disulfide formation without any difficulty. This strategy using the StBu group in combination with the widely used acetamidomethyl (Acm), 4-methylbenzyl/4-methoxybenzyl (Meb/Mob), and trityl (Trt) groups enables reliable and regioselective synthesis of multicystine peptides.
-
postsynthetic modification of unprotected peptides via s Tritylation reaction
Organic Letters, 2014Co-Authors: Masayoshi Mochizuki, Hajime Hibino, Yuji NishiuchiAbstract:Tritylation using trityl alcohol (Trt–OH) in 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) is a convenient and efficient procedure that can offer S-protection of the Cys located in fully unprotected peptides. The procedure simply requires Trt–OH and HFIP to selectively promote S-Tritylation in the presence of peptide nucleophilic functionalities.
-
Postsynthetic Modification of Unprotected Peptides via S‑Tritylation Reaction
2014Co-Authors: Masayoshi Mochizuki, Hajime Hibino, Yuji NishiuchiAbstract:Tritylation using trityl alcohol (Trt–OH) in 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) is a convenient and efficient procedure that can offer S-protection of the Cys located in fully unprotected peptides. The procedure simply requires Trt–OH and HFIP to selectively promote S-Tritylation in the presence of peptide nucleophilic functionalities
Ulrich S Schubert - One of the best experts on this subject based on the ideXlab platform.
-
homogeneous Tritylation of cellulose in 1 butyl 3 methylimidazolium chloride
Macromolecular Bioscience, 2007Co-Authors: Tina Erdmenger, Claudia Haensch, Richard Hoogenboom, Ulrich S SchubertAbstract:1-Alkyl-3-methylimidazolium-based ionic liquids, having chloride as a counter ion, were studied for cellulose solubility; and the influence of different alkyl chain lengths was also investigated. The alkyl chain length was incrementally varied from ethyl to decyl to determine structure-dissolution properties; a distinct odd-even effect was observed for short chain lengths. In addition, the Tritylation of cellulose was performed in 1-butyl-3-methylimidazolium chloride using pyridine as base. The influences of reaction time and the ratio of trityl chloride per cellulose monomer unit on the degree of substitution were investigated in detail by elemental analysis and 1H NMR spectroscopy. A DS of around 1 was obtained after 3 h reaction time using a six fold excess of trityl chloride.
