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455 results on '"Volonterio, Alessandro"'

6. Dendrimeric Guanidinoneomycin for Cellular Delivery of Bio‐macromolecules

Author

Sganappa, Aurora, Wexselblatt, Ezequiel, Bellucci, Maria Cristina, Esko, Jeffrey D, Tedeschi, Gabriella, Tor, Yitzhak, and Volonterio, Alessandro

Subjects
1.1 Normal biological development and functioning, Underpinning research, Generic health relevance, Aminoglycosides, Animals, Biotin, CHO Cells, Carbocyanines, Cell Survival, Cricetinae, Cricetulus, Dendrimers, Drug Carriers, Endocytosis, cellular uptake, dendrimers, drug delivery, guanidinium-rich transporters, guanidinoglycosides, PAMAM, Medicinal and Biomolecular Chemistry, Biochemistry and Cell Biology, Organic Chemistry
Abstract

We present the synthesis of polymeric amino- and guanidinoglycosides prepared by tethering neomycin and guanidinoneomycin to PAMAM dendrimers of generations 2 and 4. The ability of these conjugates to promote cellular uptake of high-molecular-weight cargo is discussed, together with their cytotoxicity and mechanisms of entry. We demonstrate that the presence of multiple guanidinoneomycin carriers on the PAMAM surface plays an important role in promoting cellular uptake of the dendrimers, maintaining the heparan sulfate specificity and negligible cytotoxicity typical of monomeric guanidinoglycoside molecular transporters.

Published
2017

20. Multi-Component Sequential Synthesis of Dihydroorotic Acid-Based Amphiphilic Molecules.

Author

Sani, Monica, Bellucci, Maria Cristina, and Volonterio, Alessandro

Subjects
COMBINATORIAL chemistry, MOLECULES, CATIONIC lipids
Abstract

An efficient multicomponent sequential process, which occurs in mild condition has been exploited for the synthesis of systematically modified amphiphilic molecules where the cationic head is tethered to a lipophilic tail through a dihydroorotic acid linker. The process is operatively simple, high yielding, and flexible. Such a strategy could impact combinatorial synthesis of wide libraries of amphiphilic molecules to be tested as transfection agents and/or as antimicrobials. [ABSTRACT FROM AUTHOR]

Published
2022
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28. Synthesis of 1,3,5-trisubstituted hydantoins by regiospecific domino condensation/aza-Michael/O->N acyl migration of carbodiimides with activated alpha,beta-unsaturated carboxylic acids

Author

Volonterio, Alessandro, Zanda, Matteo, and Ramirez de Arellano, Carmen

Subjects
Carboxylic acids -- Chemical properties, Chemical synthesis -- Research, Biological sciences, Chemistry
Abstract

A general, straight-forward method is developed for the preparation of 1,3,5-trisubstituted hydantoins in excellent yields by means of a new domino reaction between carboiimides and activated alpha,beta-unsaturated carboxylic acids that take place under very mild conditions. Both the regio- and chemoselectivity of the process are good, the nature of reactants, reaction parameters like the solvent, and the optional use of a base of a base promoter having strong effects are studied in detail.

Published
2005

31. Stereoselective Mannich-type reaction of an acyclic ketimine with a substituted chlorotitanium enolate: efficient approach to D-erythro-alpha-trifluoromethyl-beta-hydroxyaspartic units

Author

Bravo, Pierfrancesco, Fustero, Santos, Guidetti, Maurizia, Volonterio, Alessandro, and Zanda, Matteo

Subjects
Chemistry, Organic -- Research, Amino acids -- Research, Ring formation (Chemistry) -- Research, Biological sciences, Chemistry
Abstract

Research has been conducted on the synthesis of D-erythro-alpha-Tfm-beta-hydroxyaspartic units to investigate a streoselective Mannich-type reaction of the chlorotitanium enolate of (alpha-benzyloxy)acetyl 2-oxazolidinone with N-Cbz-imine of ethyl trifluoropyruvate. The use of 2-oxazolidinone ring system as a chiral auxiliary is analyzed.

Published
1999

33. (R)-trifluoro- and difluoropyruvaldehyde N,S-ketals: chiral synthetic equivalents of beta-trifluoro and beta-difluoro alpha-amino aldehydes

Author

Volonterio, Alessandro, Vergani, Barbara, Crucianelli, Marcello, Zanda, Matteo, and Bravo, Piefrancesco

Subjects
Stereochemistry -- Research, Alcohols -- Research, Amino compounds -- Research, Aldehydes -- Research, Biological sciences, Chemistry
Abstract

A study was conducted to characterize a technique to stereochemically determine chiral nonracemic gamma-tri- and gamma-difluoro beta-amino alcohols. Tri and difluoro-pyruvaldehyde N,S-ketals were utilized as the starting materials in the study. Results indicated that fluoropyruvaldehyde N,S-ketals can be utilized as chiral nonracemic electrophilic building blocks for the stereoselective synthesis of gamma-fluoro beta-amino alcohols.

Published
1998

34. Preparation of (R)-fluoropyruvaldehyde N,S-ketals by highly stereospecific tandem pummerer rearrangement/1,2-p-tolylthio group migration of (R)-alpha-(fluoroalkyl)-beta-sulfinylenamines

Author

Volonterio, Alessandro, Zanda, Matteo, Bravo, Pierfrancesco, Fronza, Giovanni, Cavicchio, Giancarlo, and Crucianelli, Marcello

Subjects
Organic compounds -- Synthesis, Nuclear magnetic resonance -- Analysis, Amines -- Research, Aldehydes -- Research, Biological sciences, Chemistry
Abstract

A tandem sequential process that enhances the yields of fluoropyruvaldehyde N,S-ketals and ee from alpha-(fluoroalkyl)-beta-sulfinylenamines is developed. This process is characterized by a 1,2 migration of the p-tolylthio group preceded by a Pummerer reaction. Nuclear magnetic resonance spectroscopic analysis revealed the stability of imines in the reaction process.

Published
1997

46. New fluorinated peptidomimetics through tandem aza-Michael addition to [alpha]-trifluoromethyl acrylamide acceptors: synthesis and conformational study in solid state and solution

Author

Fustero, Santos, Chiva, Gema, Piera, Julio, Sanz-Cervera, Juan F., Volonterio, Alessandro, Zanda, Matteo, and de Arellano, Carmen Ramirez

Subjects
Fluorocarbons -- Chemical properties, Fluorocarbons -- Structure, Peptides -- Chemical properties, Peptides -- Structure, Acrylamide -- Structure, Acrylamide -- Chemical properties, Biological sciences, Chemistry
Abstract

A range of partially modified retro (PMR) [psi][NHC[H.sub.2]] peptide mimetics containing hydrolytically stable C[H.sub.2]CH(C[F.sub.3])CO unit are prepared. The conformational study of the newly prepared peptidomimetics has shown a [beta]-turn-like conformation for the structures both in the solid state and in solution.

Published
2009

47. Multicomponent, one-pot sequential synthesis of 1,3,5- and 1,3,5,5-substituted barbiturates

Author

Volonterio, Alessandro and Zanda, Matteo

Subjects
Barbiturates -- Chemical properties, Electrophiles -- Chemical properties, Substitution reactions -- Analysis, Biological sciences, Chemistry
Abstract

A general and straightforward one-pot sequential synthesis of 1,3,5-trisubstituted barbiturates in very mild conditions in the presence of an electrophile to obtain 1,3,5,5-tetrasubstituted barbiturates is reported. The selective N'-deprotection of 1,3,5,5-tetrasubstituted barbiturates lead to corresponding 1,5,5-trisubstituted barbiburates.

Published
2008

48. One-step synthesis of O-benzyl hydroxamates from unactivated aliphatic and aromatic esters

Author

Gissot, Arnaud, Volonterio, Alessandro, and Zanda, Matteo

Subjects
Hydrolysis -- Analysis, Biological sciences, Chemistry
Abstract

A simple and high yielding one-step method for the synthesis of hydroxamate derivatives is developed directly from a broad range of unactivated esters and the anion of O-benzyl-hydroxylamine generated in situ. The method was successfully used with enolizable esters, including chiral alpha-amino acid esters and peptides, with no trace of racemization/epimerization at the alpha carbon detected.

Published
2005

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