The Experts below are selected from a list of 129 Experts worldwide ranked by ideXlab platform
García-granda Santiago - One of the best experts on this subject based on the ideXlab platform.
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Supramolecular chirality-sensing DNA-mimicry of a Norbornane Derivative decorated with isoxazoline and methylpyrolidine-2,5-dione ring
'Elsevier BV', 2015Co-Authors: Yakalı Gül, Karabıyık Hande, Karabıyık Hasan, Göksu Gökçe, Aygün Muhittin, García-granda SantiagoAbstract:The molecular and crystal structure of a Norbornane Derivative decorated with isoxazoline and methylpyrolidine-2,5-dione ring, C19H20N2O5, were determined and characterized by single crystal X-ray diffraction and spectroscopic methods. Details of the molecular geometry having six stereogenic centers reveal that there are two enantiomeric forms in the crystal structure of the compound, S- and R-enantiomer named with respect to the majority of chiral centers. The same type enantiomers are used as building blocks in formation of noncovalent helices by weak C-H⋯O and C-H⋯N type H-bonds. While S-enantiomers form P-helix, R-enantiomers take part in the formation of M-helix. The intertwined P- and M- helices, yielding from supramolecular chirality of the compound, are interconnected by weak C-H⋯O type H-bonds. Thus, mixed-handed noncovalent DNA mimicry of the compound contrary to natural pure-handed DNA forms is established. The presence of weak H-bonds allowing DNA mimicry of the compound in a noncovalent manner is verified by QTAIM and Hirshfeld surface analyses. To the best of our knowledge, Norbornane Derivative examined here is the first example of noncovalent DNA-mimetic based on an unnatural organic small molecule. The stability level of the H-bonded helices of the compound is comparable to those of helical peptide chains, approximately half of their stabilities.One of the authors HK is thankful to The Scientific and Technological Research Council of Turkey (TÜBÍTAK) for financial support. The work is supported by TÜBÍTAK, Grant (No. 112T636).Peer Reviewe
Sara Pellegrino - One of the best experts on this subject based on the ideXlab platform.
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β-HydroxyNorbornane amino acid Derivatives: valuable synthons for the diastereoselective preparation of substituted cyclopentylglycine Derivatives
Tetrahedron, 2008Co-Authors: Sara Pellegrino, Francesca Clerici, Maria Luisa GelmiAbstract:Abstract The behaviour towards the retro-aldol or retro-Dieckmann reactions of several norbornene and Norbornane amino acids functionalized with an oxygen atom at C-β and characterized by different features, such as the substitution pattern and the constraints, was investigated. By C2–C3 disconnection new differently functionalized cyclopentenyl- and cyclopentylglycines were prepared. This synthetic approach allows to control the stereochemistry from two to four stereocentres depending on the starting Norbornane Derivative and affords, for each Derivative, a couple of epimeric compounds at amino acid stereocentre. Depending on the features of the starting reagent and of the reaction conditions, a partial control of the stereochemistry of the amino acid carbon atom is also possible.
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beta-HydroxyNorbornane amino acid Derivatives : valuable synthons for the diastereoselective preparation of substituted cyclopentylglycine Derivatives
'Elsevier BV', 2008Co-Authors: Sara Pellegrino, Francesca Clerici, Maria Luisa GelmiAbstract:The behaviour towards the retro-aldol or retro-Dieckmann reactions of several norbornene and Norbornane amino acids functionalized with an oxygen atom at C-\u3b2 and characterized by different features, such as the substitution pattern and the constraints, was investigated. By C2-C3 disconnection new differently functionalized cyclopentenyl- and cyclopentylglycines were prepared. This synthetic approach allows to control the stereochemistry from two to four stereocentres depending on the starting Norbornane Derivative and affords, for each Derivative, a couple of epimeric compounds at amino acid stereocentre. Depending on the features of the starting reagent and of the reaction conditions, a partial control of the stereochemistry of the amino acid carbon atom is also possible
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Uncatalyzed solventless Diels–Alder reaction of 2-amino-3-nitroacrylate: synthesis of new epimeric 2-amino-3-nitro-norbornene- and Norbornane-2-carboxylic acids
Tetrahedron, 2006Co-Authors: Francesco Caputo, Maria Luisa Gelmi, Francesca Clerici, Donatella Nava, Sara PellegrinoAbstract:Abstract A highly diastereoselective Diels–Alder reaction between cyclopentadiene and ethyl (Z)-2-N-Boc-amino-3-nitroacrylate in neat conditions affords the ethyl 2-t-butoxycarbonylamino-3-endo-nitro-bicyclo[2.2.1]hept-5-ene-2-exo-carboxylate: a new constrained carbocyclic amino acid. Catalytic hydrogenation of this cycloadduct gave the corresponding reduced Norbornane Derivative. A preliminary investigation into the chemistry of these two amino acids was performed. In particular, the epimerization to their corresponding 3-exo-nitro compounds by treatment both with acid and base was studied. From this study, valuable information on the endo/exo process at the C-3 carbon atom, as well as on the stability of the different stereomers, was obtained. The stability is closely related to the presence or the absence of the double bond in the ring and to the substitution pattern. Finally, deprotection of the amino acid function has been performed.
Maria Luisa Gelmi - One of the best experts on this subject based on the ideXlab platform.
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β-HydroxyNorbornane amino acid Derivatives: valuable synthons for the diastereoselective preparation of substituted cyclopentylglycine Derivatives
Tetrahedron, 2008Co-Authors: Sara Pellegrino, Francesca Clerici, Maria Luisa GelmiAbstract:Abstract The behaviour towards the retro-aldol or retro-Dieckmann reactions of several norbornene and Norbornane amino acids functionalized with an oxygen atom at C-β and characterized by different features, such as the substitution pattern and the constraints, was investigated. By C2–C3 disconnection new differently functionalized cyclopentenyl- and cyclopentylglycines were prepared. This synthetic approach allows to control the stereochemistry from two to four stereocentres depending on the starting Norbornane Derivative and affords, for each Derivative, a couple of epimeric compounds at amino acid stereocentre. Depending on the features of the starting reagent and of the reaction conditions, a partial control of the stereochemistry of the amino acid carbon atom is also possible.
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beta-HydroxyNorbornane amino acid Derivatives : valuable synthons for the diastereoselective preparation of substituted cyclopentylglycine Derivatives
'Elsevier BV', 2008Co-Authors: Sara Pellegrino, Francesca Clerici, Maria Luisa GelmiAbstract:The behaviour towards the retro-aldol or retro-Dieckmann reactions of several norbornene and Norbornane amino acids functionalized with an oxygen atom at C-\u3b2 and characterized by different features, such as the substitution pattern and the constraints, was investigated. By C2-C3 disconnection new differently functionalized cyclopentenyl- and cyclopentylglycines were prepared. This synthetic approach allows to control the stereochemistry from two to four stereocentres depending on the starting Norbornane Derivative and affords, for each Derivative, a couple of epimeric compounds at amino acid stereocentre. Depending on the features of the starting reagent and of the reaction conditions, a partial control of the stereochemistry of the amino acid carbon atom is also possible
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Uncatalyzed solventless Diels–Alder reaction of 2-amino-3-nitroacrylate: synthesis of new epimeric 2-amino-3-nitro-norbornene- and Norbornane-2-carboxylic acids
Tetrahedron, 2006Co-Authors: Francesco Caputo, Maria Luisa Gelmi, Francesca Clerici, Donatella Nava, Sara PellegrinoAbstract:Abstract A highly diastereoselective Diels–Alder reaction between cyclopentadiene and ethyl (Z)-2-N-Boc-amino-3-nitroacrylate in neat conditions affords the ethyl 2-t-butoxycarbonylamino-3-endo-nitro-bicyclo[2.2.1]hept-5-ene-2-exo-carboxylate: a new constrained carbocyclic amino acid. Catalytic hydrogenation of this cycloadduct gave the corresponding reduced Norbornane Derivative. A preliminary investigation into the chemistry of these two amino acids was performed. In particular, the epimerization to their corresponding 3-exo-nitro compounds by treatment both with acid and base was studied. From this study, valuable information on the endo/exo process at the C-3 carbon atom, as well as on the stability of the different stereomers, was obtained. The stability is closely related to the presence or the absence of the double bond in the ring and to the substitution pattern. Finally, deprotection of the amino acid function has been performed.
Yakalı Gül - One of the best experts on this subject based on the ideXlab platform.
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Supramolecular chirality-sensing DNA-mimicry of a Norbornane Derivative decorated with isoxazoline and methylpyrolidine-2,5-dione ring
'Elsevier BV', 2015Co-Authors: Yakalı Gül, Karabıyık Hande, Karabıyık Hasan, Göksu Gökçe, Aygün Muhittin, García-granda SantiagoAbstract:The molecular and crystal structure of a Norbornane Derivative decorated with isoxazoline and methylpyrolidine-2,5-dione ring, C19H20N2O5, were determined and characterized by single crystal X-ray diffraction and spectroscopic methods. Details of the molecular geometry having six stereogenic centers reveal that there are two enantiomeric forms in the crystal structure of the compound, S- and R-enantiomer named with respect to the majority of chiral centers. The same type enantiomers are used as building blocks in formation of noncovalent helices by weak C-H⋯O and C-H⋯N type H-bonds. While S-enantiomers form P-helix, R-enantiomers take part in the formation of M-helix. The intertwined P- and M- helices, yielding from supramolecular chirality of the compound, are interconnected by weak C-H⋯O type H-bonds. Thus, mixed-handed noncovalent DNA mimicry of the compound contrary to natural pure-handed DNA forms is established. The presence of weak H-bonds allowing DNA mimicry of the compound in a noncovalent manner is verified by QTAIM and Hirshfeld surface analyses. To the best of our knowledge, Norbornane Derivative examined here is the first example of noncovalent DNA-mimetic based on an unnatural organic small molecule. The stability level of the H-bonded helices of the compound is comparable to those of helical peptide chains, approximately half of their stabilities.One of the authors HK is thankful to The Scientific and Technological Research Council of Turkey (TÜBÍTAK) for financial support. The work is supported by TÜBÍTAK, Grant (No. 112T636).Peer Reviewe
Santiago García-granda - One of the best experts on this subject based on the ideXlab platform.
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Supramolecular chirality-sensing DNA-mimicry of a Norbornane Derivative decorated with isoxazoline and methylpyrolidine-2,5-dione ring
Journal of Molecular Structure, 2013Co-Authors: Gül Yakalı, Hande Karabıyık, Gokce Goksu, Muhittin Aygün, Nuket Ocal, Santiago García-grandaAbstract:One of the authors HK is thankful to The Scientific and Technological Research Council of Turkey (TUBITAK) for financial support. The work is supported by TUBITAK, Grant (No. 112T636).
