Giovanni Valle

University of Padua

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Claudio Toniolo

University of Padua

Marco Crisma

University of Padua

Paolo Ganis

University of Padua

Fernando Formaggio

University of Padua

Sandro Calogero

Ca' Foscari University of Venice

Ottorino De Lucchi

Università Iuav di Venezia

Gian Maria Bonora

University of Trieste

Umberto Russo

Ospedale Santa Chiara

Marino Basato

University of Padua

Alessandro Gambaro

University of Padua

Cooperative Institutions

University of Padua

135

Istituto di Chimica Biomolecolare

Centre National de la Recherche Scientifique

University of Naples Federico II

University of Florence

University of Bologna

National Interuniversity Consortium of Materials Science and Technology

Institute of Molecular Science and Technologies

Università di Camerino

National Research Council

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Structural versatility of peptides from C^α,α-disubstituted glycines. Preferred conformation of the C^α,α-dibenzylglycine residue

Journal of the Chemical Society. Perkin transactions II (1990)

Giovanni Valle Marco Crisma Gian Maria Bonora Claudio Toniolo Francesco Lelj

The preferred conformation of the Cα,α-dibenzylglycine residue has been assessed in selected derivatives and small peptides by conformational energy computations, 1H NMR spectroscopy, and X-ray diffraction. Conformational energy computations on the Cα,α-dibenzylglycine monopeptide, Ac-Dbz-NHMe, strongly support the view that this Cα,α-symmetrically disubstituted residue is conformationally restricted and that its minimum energy conformation falls in the fully-extended (C5) region. The results of the theoretical analysis are in agreement with the solution and crystal-state structural propensity of Tfa-Dbz-Gly-DBH, Tfa-Dbz-L-Phe-OMe and its benzyl ester analogue, m-ClAc-Dbz-OH, Z-Gly-Dbz-Gly-OH and its t-butyl ester derivative. The implications for the use of the Dbz residue in designing conformationally constrained analogues of bioactive peptides are briefly discussed.

Residue (chemistry)

10.1039/p29900001481

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Citations (16)

Mono- and polynuclear chloro complexes of palladium(II) with α-substituted thioethers

Inorganica Chimica Acta (2000)

Marino Basato Annarita Cardinale Marco Zecca Giovanni Valle

10.1016/s0020-1693(99)00527-7

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Citations (8)

Linear oligopeptides. 118. Preferred conformations and modes of self-association of the fluoren-9-ylmethoxycarbonyl amino acid derivatives

Canadian Journal of Chemistry (1984)

Giovanni Valle Gian Maria Bonora Claudio Toniolo

An analysis of the preferred conformations and modes of self-association of the N-fluoren-9-methoxycarbonyl derivatives of L-alanine and α-aminoisobutyric acid was performed in solution and in the solid state using infrared absorption, 1 H nuclear magnetic resonance, and X-ray diffraction. In a solvent of low polarity (deuterochloroform) non-associated and self-associated species (involving predominantly the hydroxyl and carbonyl groups of the carboxylic acid moiety) simultaneously occur. At high dilution, where self-association is absent, the amount of intramolecularly H-bonded forms, if any, should be extremely small. Z(trans) [Formula: see text]E(cis) isomerism about the amide bond of the secondary urethane moiety was observed only for the less bulky L-alanine derivative. In the solid state all H-bonding donors and acceptors of the L-alanine and α-aminoisobutyric acid derivatives take part to complex schemes of intermolecular H-bonds. In the L-alanine derivative, crystallized as monohydrate, most of the intermolecular H-bonds involve the water molecule. Intramolecular H-bonds are not observed in either compound. The conformation about the secondary urethane CO—NH bond is Z(trans) in both compounds. Both L-alanine and α-aminoisobutyric acid residues are partially folded. The observation of the long C(sp 3 )—O bond of the fluoren-9-yl-methoxycarbonyl moiety might contribute to explain the unexpected experimental result that this protecting group can be removed by catalytic hydrogenation.

Moiety

Alanine

Amide

Peptide bond

Derivative (finance)

10.1139/v84-452

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Citations (16)

Metal complexes of 2-(o-hydroxyphenyl)pyridine

Inorganica Chimica Acta (1988)

Paolo Ganis Antonio Saporito Aldo Vitagliano Giovanni Valle

Orthorhombic crystal system

10.1016/s0020-1693(00)80661-1

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Citations (25)

Synthesis of Structurally Modified Atropisomeric Biaryl Dithiols. Observations on the Newman-Kwart Rearrangement

Tetrahedron (1997)

Sergio Cossu Ottorino De Lucchi Davide Fabbri Giovanni Valle Gavin F. Painter

Carbanion

10.1016/s0040-4020(97)00268-8

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Citations (47)

Crystal structure and mass spectrometry of dichlorodimethylbis[2(1H)-pyridinethione-S]tin(IV)

Journal of the Chemical Society. Dalton transactions (1987)

Giovanni Valle R. Ettorre Umberto Vettori Valerio Peruzzo Gualtiero Plazzogna

The structure of the complex Sn(CH3)2Cl2·2C5H5NS has been determined by single-crystal X-ray diffraction methods. The compound crystallizes in the monoclinic system, space group P21/n, with unit-cell dimensions a= 16.793(5), b= 6.201(3), c= 7.882(3)Å, β= 90.4(3)°, and Z= 2. The configuration about the tin atom is all-trans octahedral. The C5H5NS ligands are bonded to the metal through the S atom. The observed C(2)–S bond length [1.730(g)Å] is consistent with ca. 35% double-bond character, compared to ca. 55% for the uncomplexed ligand. The H atoms on the N atoms are involved in intramolecular hydrogen bonding with the chloride ligands, N–H ⋯ Cl 3.199(9)Å. Mass spectra of Sn(CH3)2Cl2·2C5H5NS show that facile elimination of HCl from the complex occurs to give a series of ions containing the ligand C5H4NS; these can be formulated as complexes of the 2-pyridinethiolate anion, probably bonded through the S atom. Mass spectra of the metastable ion [Sn(CH3)Cl(C5H4NS)]+ show that the Sn–L bond strengths are in the order L = methyl < chlorine < 2-pyridinethiolate.

Monoclinic crystal system

10.1039/dt9870000815

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Citations (34)

Crystal structures of three substituted ammonium hexachlororhenates(IV)

Zeitschrift für Kristallographie - Crystalline Materials (1989)

Marco Bettinelli L. Di Sipio Giovanni Valle Carla Aschieri Gianluigi Ingletto

Article Crystal structures of three substituted ammonium hexachlororhenates(IV) was published on October 1, 1989 in the journal Zeitschrift für Kristallographie - Crystalline Materials (volume 188, issue 1-4).

Crystal (programming language)

10.1524/zkri.1989.188.14.155

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Citations (2)

Synthesis and x-ray crystal structure of a tin(IV) tetrahalide adduct with a crown ether

Inorganica Chimica Acta (1984)

Giovanni Valle A. Cassol Umberto Russo

Monoclinic crystal system

10.1016/s0020-1693(00)82542-6

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Citations (32)

Metal complexes of 2-(o-hydroxyphenyl)pyridine

Inorganica Chimica Acta (1989)

Paolo Ganis Antonio Saporito Aldo Vitagliano Giovanni Valle

10.1016/s0020-1693(00)83436-2

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Citations (0)

Reactions of β-dicarbonyl compounds with acyl cyanides catalyzed or promoted by metal centres in the homogeneous phase

Journal of the Chemical Society. Perkin transactions I/Journal of the Chemical Society. Perkin transactions. I (1994)

Augusto C. Veronese Rosella Callegari Marino Basato Giovanni Valle

The C–C bond-forming reaction between β-dicarbonyl compounds and acyl cyanides is catalyzed by nickel acetylacetonate or promoted by tin tetrachloride. Thus, β-diketones react with acyl cyanides in the presence of catalytic amounts of [Ni(acac)2] to give β-enamino diketones 3. β-Enamino keto esters 8 or β-enamino diesters 9 are obtained in the reactions of methyl acetoacetate or methyl malonate with acyl cyanides in the presence of stoichiometric amounts of SnCl4. The reactions of acyl cyanides with methyl malonate also afford furanone derivatives 10, whose structure has been determined, in one case, by a single-crystal X-ray analysis. β-Keto amides react with acyl cyanides to give pyrrolidine derivatives 13 both under catalytic conditions and stoichiometric conditions where an equimolar equivalent of promoter was used.

Malonate

Stoichiometry

Pyrrolidine

Diethyl malonate

10.1039/p19940001779

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Citations (22)