Lucas sousa madureira - Academia.edu (original) (raw)

Papers by Lucas sousa madureira

Research paper thumbnail of CCDC 1452100: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research paper thumbnail of CCDC 1452099: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research paper thumbnail of CCDC 1451922: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research paper thumbnail of CCDC 922575: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research paper thumbnail of CCDC 922574: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research paper thumbnail of CCDC 922573: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research paper thumbnail of CCDC 1435169: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research paper thumbnail of CCDC 1435168: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research paper thumbnail of CCDC 1435167: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research paper thumbnail of Article Synthesis, Molecular and Crystal Structure Analysis of 1-(4-Methylbenzenesulfonyl)indole-3-carbaldehyde and DFT Investigation of Its Rotational Conformers

Two independent molecules that differ in terms of rotation about the central S-N bond comprise th... more Two independent molecules that differ in terms of rotation about the central S-N bond comprise the asymmetric unit of the title compound 1. The molecules have a V-shape with the dihedral angles between the fused ring system and benzene ring being 79.08(6)° and 72.83(5)°, respectively. The packing is mostly driven by ••• interactions occurring between the tolyl ring of one molecule and the C 6 ring of the indole fused ring system of the other. DFT and IRC calculations for these and related 1-(arylsulfonyl)indole molecules showed that the rotational barrier about the S-N bond between conformers is within the 2.5-5.5 kcal/mol range. Crystal data for C 16 H 13 NO 3 S (1):

Research paper thumbnail of CCDC 935801: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research paper thumbnail of Uso da modelagem molecular na solução de problemas em química

Assinaturas dos membros da comissão examinadora que avaliou e aprovou a defesa de tese de Doutora... more Assinaturas dos membros da comissão examinadora que avaliou e aprovou a defesa de tese de Doutorado do candidato Lucas Sousa Madureira, realizada em 29 de agosto de 2014:

Research paper thumbnail of 4-Benzyl-1-(4-nitro-phen-yl)-1H-1,2,3-triazole: crystal structure and Hirshfeld analysis

Acta crystallographica. Section E, Crystallographic communications, 2017

The mol-ecule in the title compound, C15H12N4O2, has a twisted L-shape with the dihedral angle be... more The mol-ecule in the title compound, C15H12N4O2, has a twisted L-shape with the dihedral angle between the aromatic rings of the N-bound benzene and C-bound benzyl groups being 70.60 (9)°. The nitro group is co-planar with the benzene ring to which it is connected [C-C-N-O torsion angle = 0.4 (3)°]. The three-dimensional packing is stabilized by a combination of methyl-ene-C-H⋯O(nitro), methyl-ene-C-H⋯π(phen-yl), phenyl-C-H⋯π(triazol-yl) and nitro-O⋯π(nitro-benzene) inter-actions, along with weak π(triazol-yl)-π(nitrobenzene) contacts [inter-centroid distance = 3.8386 (10) Å]. The importance of the specified inter-molecular contacts has been verified by an analysis of the calculated Hirshfeld surface.

Research paper thumbnail of 1-Butyl-1-chloro-3-methyl-3H-2,1λ(4)-benzoxa-tellurole: crystal structure and Hirshfeld analysis

Acta crystallographica. Section E, Crystallographic communications, 2017

Two independent mol-ecules comprise the asymmetric unit in the title benzoxatellurole compound, C... more Two independent mol-ecules comprise the asymmetric unit in the title benzoxatellurole compound, C12H17ClOTe. The mol-ecules, with the same chirality at the methine C atom, are connected into a loosely associated dimer by Te⋯O inter-actions, leading to a {⋯Te-O}2 core. The resultant C2ClO2 donor set approximates a square pyramid with the lone pair of electrons projected to occupy a position trans to the n-butyl substituent. Inter-estingly, the Te(IV) atoms exhibit opposite chirality. The major difference between the independent mol-ecules relates to the conformation of the five-membered chelate rings, which is an envelope with the O atom being the flap, in one mol-ecule and is twisted about the O-C(methine) bond in the other. No directional inter-molecular inter-actions are noted in the mol-ecular packing beyond the aforementioned Te⋯O secondary bonding. The analysis of the Hirshfeld surface reveals the dominance of H⋯H contacts, i.e. contributing about 70% to the overall surface, an...

Research paper thumbnail of Structural, Hirshfeld surface and theoretical analysis of two conformational polymorphs of N,N′-bis(pyridin-3-ylmethyl)oxalamide

Zeitschrift für Kristallographie - Crystalline Materials, 2016

The common feature of two conformational polymorphs of N,N′-bis(pyridin-3-ylmethyl)oxalamide is t... more The common feature of two conformational polymorphs of N,N′-bis(pyridin-3-ylmethyl)oxalamide is their crystallisation in the monoclinic space group P21/c with Z=4. In low symmetry form 1, the central core is effectively planar and the terminal pyridyl rings adopt a syn-periplanar conformation. In the high symmetry form, 2, there are two independent molecules in the asymmetric unit but each is located about a centre of inversion. The rings again are almost perpendicular to the central plane but, from symmetry are anti-periplanar. Computational chemistry shows that symmetric molecules with syn (two-fold) and anti (centrosymmetric) conformations have nearly identical energies. In the molecular packing of each of 1 and 2, supramolecular tapes based on amide-N–H···O(amide) hydrogen bonding are found. In 1, these are connected into layers by C–H···N(pyridyl) interactions, while in 2, the chains are linked into a three-dimensional architecture by C–H···N(pyridyl) interactions. The importan...

Research paper thumbnail of ChemInform Abstract: Ligand and Copper Free Sonogashira Coupling to Achieve 2-Alkynyl D-Glucal Derivatives: Regioselective Electrophile Promoted Nucleophilic 5-endo-Dig Cyclization

ChemInform, 2016

A very efficient Pd(OAc)2 catalyzed copper and ligand free Sonogashira coupling reaction is devel... more A very efficient Pd(OAc)2 catalyzed copper and ligand free Sonogashira coupling reaction is developed.

Research paper thumbnail of Structural systematics of aryl-1,3-dithiane derivatives: crystal and energy-minimised structures, and Hirshfeld surface analysis

Zeitschrift für Kristallographie - Crystalline Materials, 2016

The crystal structure analysis of three aryl-1,3-dithiane derivatives, with aryl=4-methylphenyl (... more The crystal structure analysis of three aryl-1,3-dithiane derivatives, with aryl=4-methylphenyl (1), 4-chlorophenyl (2) and 2,4-dichlorophenyl (3), shows the three molecules to have very similar conformations, with the aryl ring lying on an approximate mirror plane that bisects the dithiane ring which adopts a chair conformation; the energy-minimised structures are consistent with the experimental structures. The greater barrier to rotation about the methine-C–C(ipso) bond in 3, cf. 1 and 2, is related to unfavourable intramolecular S···Cl interactions in the putative transition state. The molecular packing in 1–3, while globally similar, are distinct, being based on combinations of identifiable C–H···π(arene), C–H···S and C–Cl···π(arene) interactions. The lack of isostructural relationships points to the significance of the identified intermolecular interactions to direct molecular packing.

Research paper thumbnail of Conformational preferences for isomeric N,N′-bis(pyridin-n-ylmethyl)ethanedithiodiamides, n = 2, 3 and 4: a combined crystallographic and DFT study

Zeitschrift für Kristallographie - Crystalline Materials, 2015

Crystal structure analysis of the isomeric N,N′-bis(pyridin-n-ylmethyl)ethanedithioamides, n = 2 ... more Crystal structure analysis of the isomeric N,N′-bis(pyridin-n-ylmethyl)ethanedithioamides, n = 2 (1), 3 (2) and 4 (3), show a planar conformation for 1 and conformations whereby the pyridyl rings lie orthogonal and to either side of the central residue for each of 2 and 3. The universal adoption of the all ZZ conformation about the central C–N bonds, which have double bond character, is ascribed to the presence of intramolecular N–H…S hydrogen bonds that close S(5) rings. The gas-phase geometry optimised structure for 1 is the same as the experimental structure which features intramolecular amine-N–H…N(pyridyl) hydrogen bonds. The open structures found for 2 and 3 differ from the somewhat flattened optimised structures. Systematic variations in the geometric parameters characterising the central C2N2S2 residue, in particular the double-bond character of the C–N bond and the elongation of the central C–C bond are shown by theory to be due to conjugative nN → π*C=S interactions and nS...

Research paper thumbnail of Influência do empacotamento cristalino nas conformações de N,N-bis(piridina-n-ilmetil) etanodiamidas e tioamidas análogas (n= 2, 3, 4)

Research paper thumbnail of Ligand and copper free Sonogashira coupling to achieve 2-alkynyl d-glucal derivatives: regioselective electrophile promoted nucleophilic 5-endo-dig cyclization

Tetrahedron Letters, 2015

Abstract A general approach for the synthesis of 2-alkynyl- d -glucal derivatives has been achiev... more Abstract A general approach for the synthesis of 2-alkynyl- d -glucal derivatives has been achieved through a ligand and copper-free Sonogashira coupling of 2-iodo-3,4,6-tri- O -acetyl- d -glucal and terminal alkynes using palladium acetate in DMF at room temperature with very good to excellent yields. The scope of this reaction is shown by regioselective electrophile promoted nucleophilic (EPN) 5- endo -dig cyclization of these alkynyl- d -glucal derivatives using gold(III) chloride in 1,4-dioxane at reflux.

Research paper thumbnail of CCDC 1452100: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research paper thumbnail of CCDC 1452099: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research paper thumbnail of CCDC 1451922: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research paper thumbnail of CCDC 922575: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research paper thumbnail of CCDC 922574: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research paper thumbnail of CCDC 922573: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research paper thumbnail of CCDC 1435169: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research paper thumbnail of CCDC 1435168: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research paper thumbnail of CCDC 1435167: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research paper thumbnail of Article Synthesis, Molecular and Crystal Structure Analysis of 1-(4-Methylbenzenesulfonyl)indole-3-carbaldehyde and DFT Investigation of Its Rotational Conformers

Two independent molecules that differ in terms of rotation about the central S-N bond comprise th... more Two independent molecules that differ in terms of rotation about the central S-N bond comprise the asymmetric unit of the title compound 1. The molecules have a V-shape with the dihedral angles between the fused ring system and benzene ring being 79.08(6)° and 72.83(5)°, respectively. The packing is mostly driven by ••• interactions occurring between the tolyl ring of one molecule and the C 6 ring of the indole fused ring system of the other. DFT and IRC calculations for these and related 1-(arylsulfonyl)indole molecules showed that the rotational barrier about the S-N bond between conformers is within the 2.5-5.5 kcal/mol range. Crystal data for C 16 H 13 NO 3 S (1):

Research paper thumbnail of CCDC 935801: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research paper thumbnail of Uso da modelagem molecular na solução de problemas em química

Assinaturas dos membros da comissão examinadora que avaliou e aprovou a defesa de tese de Doutora... more Assinaturas dos membros da comissão examinadora que avaliou e aprovou a defesa de tese de Doutorado do candidato Lucas Sousa Madureira, realizada em 29 de agosto de 2014:

Research paper thumbnail of 4-Benzyl-1-(4-nitro-phen-yl)-1H-1,2,3-triazole: crystal structure and Hirshfeld analysis

Acta crystallographica. Section E, Crystallographic communications, 2017

The mol-ecule in the title compound, C15H12N4O2, has a twisted L-shape with the dihedral angle be... more The mol-ecule in the title compound, C15H12N4O2, has a twisted L-shape with the dihedral angle between the aromatic rings of the N-bound benzene and C-bound benzyl groups being 70.60 (9)°. The nitro group is co-planar with the benzene ring to which it is connected [C-C-N-O torsion angle = 0.4 (3)°]. The three-dimensional packing is stabilized by a combination of methyl-ene-C-H⋯O(nitro), methyl-ene-C-H⋯π(phen-yl), phenyl-C-H⋯π(triazol-yl) and nitro-O⋯π(nitro-benzene) inter-actions, along with weak π(triazol-yl)-π(nitrobenzene) contacts [inter-centroid distance = 3.8386 (10) Å]. The importance of the specified inter-molecular contacts has been verified by an analysis of the calculated Hirshfeld surface.

Research paper thumbnail of 1-Butyl-1-chloro-3-methyl-3H-2,1λ(4)-benzoxa-tellurole: crystal structure and Hirshfeld analysis

Acta crystallographica. Section E, Crystallographic communications, 2017

Two independent mol-ecules comprise the asymmetric unit in the title benzoxatellurole compound, C... more Two independent mol-ecules comprise the asymmetric unit in the title benzoxatellurole compound, C12H17ClOTe. The mol-ecules, with the same chirality at the methine C atom, are connected into a loosely associated dimer by Te⋯O inter-actions, leading to a {⋯Te-O}2 core. The resultant C2ClO2 donor set approximates a square pyramid with the lone pair of electrons projected to occupy a position trans to the n-butyl substituent. Inter-estingly, the Te(IV) atoms exhibit opposite chirality. The major difference between the independent mol-ecules relates to the conformation of the five-membered chelate rings, which is an envelope with the O atom being the flap, in one mol-ecule and is twisted about the O-C(methine) bond in the other. No directional inter-molecular inter-actions are noted in the mol-ecular packing beyond the aforementioned Te⋯O secondary bonding. The analysis of the Hirshfeld surface reveals the dominance of H⋯H contacts, i.e. contributing about 70% to the overall surface, an...

Research paper thumbnail of Structural, Hirshfeld surface and theoretical analysis of two conformational polymorphs of N,N′-bis(pyridin-3-ylmethyl)oxalamide

Zeitschrift für Kristallographie - Crystalline Materials, 2016

The common feature of two conformational polymorphs of N,N′-bis(pyridin-3-ylmethyl)oxalamide is t... more The common feature of two conformational polymorphs of N,N′-bis(pyridin-3-ylmethyl)oxalamide is their crystallisation in the monoclinic space group P21/c with Z=4. In low symmetry form 1, the central core is effectively planar and the terminal pyridyl rings adopt a syn-periplanar conformation. In the high symmetry form, 2, there are two independent molecules in the asymmetric unit but each is located about a centre of inversion. The rings again are almost perpendicular to the central plane but, from symmetry are anti-periplanar. Computational chemistry shows that symmetric molecules with syn (two-fold) and anti (centrosymmetric) conformations have nearly identical energies. In the molecular packing of each of 1 and 2, supramolecular tapes based on amide-N–H···O(amide) hydrogen bonding are found. In 1, these are connected into layers by C–H···N(pyridyl) interactions, while in 2, the chains are linked into a three-dimensional architecture by C–H···N(pyridyl) interactions. The importan...

Research paper thumbnail of ChemInform Abstract: Ligand and Copper Free Sonogashira Coupling to Achieve 2-Alkynyl D-Glucal Derivatives: Regioselective Electrophile Promoted Nucleophilic 5-endo-Dig Cyclization

ChemInform, 2016

A very efficient Pd(OAc)2 catalyzed copper and ligand free Sonogashira coupling reaction is devel... more A very efficient Pd(OAc)2 catalyzed copper and ligand free Sonogashira coupling reaction is developed.

Research paper thumbnail of Structural systematics of aryl-1,3-dithiane derivatives: crystal and energy-minimised structures, and Hirshfeld surface analysis

Zeitschrift für Kristallographie - Crystalline Materials, 2016

The crystal structure analysis of three aryl-1,3-dithiane derivatives, with aryl=4-methylphenyl (... more The crystal structure analysis of three aryl-1,3-dithiane derivatives, with aryl=4-methylphenyl (1), 4-chlorophenyl (2) and 2,4-dichlorophenyl (3), shows the three molecules to have very similar conformations, with the aryl ring lying on an approximate mirror plane that bisects the dithiane ring which adopts a chair conformation; the energy-minimised structures are consistent with the experimental structures. The greater barrier to rotation about the methine-C–C(ipso) bond in 3, cf. 1 and 2, is related to unfavourable intramolecular S···Cl interactions in the putative transition state. The molecular packing in 1–3, while globally similar, are distinct, being based on combinations of identifiable C–H···π(arene), C–H···S and C–Cl···π(arene) interactions. The lack of isostructural relationships points to the significance of the identified intermolecular interactions to direct molecular packing.

Research paper thumbnail of Conformational preferences for isomeric N,N′-bis(pyridin-n-ylmethyl)ethanedithiodiamides, n = 2, 3 and 4: a combined crystallographic and DFT study

Zeitschrift für Kristallographie - Crystalline Materials, 2015

Crystal structure analysis of the isomeric N,N′-bis(pyridin-n-ylmethyl)ethanedithioamides, n = 2 ... more Crystal structure analysis of the isomeric N,N′-bis(pyridin-n-ylmethyl)ethanedithioamides, n = 2 (1), 3 (2) and 4 (3), show a planar conformation for 1 and conformations whereby the pyridyl rings lie orthogonal and to either side of the central residue for each of 2 and 3. The universal adoption of the all ZZ conformation about the central C–N bonds, which have double bond character, is ascribed to the presence of intramolecular N–H…S hydrogen bonds that close S(5) rings. The gas-phase geometry optimised structure for 1 is the same as the experimental structure which features intramolecular amine-N–H…N(pyridyl) hydrogen bonds. The open structures found for 2 and 3 differ from the somewhat flattened optimised structures. Systematic variations in the geometric parameters characterising the central C2N2S2 residue, in particular the double-bond character of the C–N bond and the elongation of the central C–C bond are shown by theory to be due to conjugative nN → π*C=S interactions and nS...

Research paper thumbnail of Influência do empacotamento cristalino nas conformações de N,N-bis(piridina-n-ilmetil) etanodiamidas e tioamidas análogas (n= 2, 3, 4)

Research paper thumbnail of Ligand and copper free Sonogashira coupling to achieve 2-alkynyl d-glucal derivatives: regioselective electrophile promoted nucleophilic 5-endo-dig cyclization

Tetrahedron Letters, 2015

Abstract A general approach for the synthesis of 2-alkynyl- d -glucal derivatives has been achiev... more Abstract A general approach for the synthesis of 2-alkynyl- d -glucal derivatives has been achieved through a ligand and copper-free Sonogashira coupling of 2-iodo-3,4,6-tri- O -acetyl- d -glucal and terminal alkynes using palladium acetate in DMF at room temperature with very good to excellent yields. The scope of this reaction is shown by regioselective electrophile promoted nucleophilic (EPN) 5- endo -dig cyclization of these alkynyl- d -glucal derivatives using gold(III) chloride in 1,4-dioxane at reflux.