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131 KiB

Open AccessArticle

Synthesis and Characterization of Acyclic and Cyclic Azabridged Ligands Incorporating 2,2'-Bipyridine Subunits and Their Complexes With Copper(II), Cobalt(II), and Nickel(II)

by Antonino Mamo and Andrea Pappalardo

Molecules 2003, 8(7), 521-535; https://doi.org/10.3390/80700521 - 15 Jul 2003

Cited by 2 | Viewed by 10016

Abstract

The synthesis of a series of N,N'-disubstituted acyclic (AL) and cyclic (CL) aza-bridged ligands incorporating 2,2-pipryidine subunits is described. ¹H-NMR and IR spectral data support the proposed ligand structures. Dynamic ¹H-NMR studies on diurea and diamide derivatives point to the presence [...] Read more.

The synthesis of a series of N,N'-disubstituted acyclic (AL) and cyclic (CL) aza-bridged ligands incorporating 2,2-pipryidine subunits is described. ¹H-NMR and IR spectral data support the proposed ligand structures. Dynamic ¹H-NMR studies on diurea and diamide derivatives point to the presence of slowly interconverting conformers on the ¹H-NMR time-scale, owing to N−H···N hydrogen bonding and/or a restricted rotation around the amide bonds. The ligands synthesized form 1:1 complexes with divalent transition metal ions. Upon complexation, bis-ester derivatives AL₅ and CL₅ undergo a metal-induced hydrolysis of the ester groups to carboxyl functions, which act as additional binding sites for the metal ion, as well as hydrogen-bonding donor-acceptor binding site to produce dimeric complexes. Full article

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109 KiB

Open AccessArticle

Synthesis and Reactivity of New 1-Pentafluorophenyl-1Hpyrrole Derivatives

by Katarína Hrnčariková and Daniel Végh

Molecules 2003, 8(7), 536-540; https://doi.org/10.3390/80700536 - 15 Jul 2003

Cited by 11 | Viewed by 7844

Abstract

We present 1-pentafluorophenyl-1H-pyrrole and some of its electrophilic substitution reactions: formylation and acetylations. The 2-substituted products formed in these reactions are selectively and in high yield converted into 3-substituted products by treatment with trifluoromethanesulfonic acid. A general synthesis of 3-acylpyrroles was developed by [...] Read more.

We present 1-pentafluorophenyl-1H-pyrrole and some of its electrophilic substitution reactions: formylation and acetylations. The 2-substituted products formed in these reactions are selectively and in high yield converted into 3-substituted products by treatment with trifluoromethanesulfonic acid. A general synthesis of 3-acylpyrroles was developed by the trifluoromethanesulfonic acid-mediated rearrangement of the corresponding 2-acylpyrroles. Full article

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133 KiB

Open AccessArticle

Microwave Assisted Synthesis, Part 1: Rapid Solventless Synthesis of 3-Substituted Coumarins and Benzocoumarins by Microwave Irradiation of the Corresponding Enaminones

by Khadijah M. Al-Zaydi

Molecules 2003, 8(7), 541-555; https://doi.org/10.3390/80700541 - 15 Jul 2003

Cited by 50 | Viewed by 10363

Abstract

The reactivity of enaminones toward a variety of reagents under microwave irradiation is reported. The results are compared with traditional solution methods. Full article

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52 KiB

Open AccessArticle

Synthesis of Plasmepsin II Inhibitors – Potential Antimalarial Agents

by Reto Mueller, Marianne Huerzeler and Christoph Boss

Molecules 2003, 8(7), 556-564; https://doi.org/10.3390/80700556 - 15 Jul 2003

Cited by 12 | Viewed by 9249

Abstract

A new series of plasmepsin II (PM II) inhibitors has been prepared based on 4-aminopiperidine-tert-butyl-carbamate (1). These compounds might be useful as antimalarial drugs acting via a new mechanism, and therefore be less susceptible to parasite resistance now often observed with [...] Read more.

A new series of plasmepsin II (PM II) inhibitors has been prepared based on 4-aminopiperidine-tert-butyl-carbamate (1). These compounds might be useful as antimalarial drugs acting via a new mechanism, and therefore be less susceptible to parasite resistance now often observed with current antimalarial therapies. Some of the final compounds prepared exhibited encouraging inhibitory activity towards PM II. Full article

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3765 KiB

Open AccessArticle

Phthalimides: Supramolecular Interactions in Crystals, Hypersensitive Solution 1H-NMR Dynamics and Energy Transfer to Europium(III) and Terbium(III) States

by Robertha C. Howell, Selvin H. Edwards, Alison S. Gajadhar-Plummer, Ishenkumba A. Kahwa, Gary L. McPherson, Joel T. Mague, Andrew J. P. White and David J. Williams

Molecules 2003, 8(7), 565-592; https://doi.org/10.3390/molecules8070565 - 15 Jul 2003

Cited by 13 | Viewed by 12548

Abstract

Detailed crystal structures and ¹H-NMR characteristics of some alkylaminephthalimides, including dendritic polyphthalimides, are reported. These investigations were undertaken in order to obtain a better understanding of the relationship between solid-state supramolecular interactions, their persistence in solution and associated dynamics of magnetically hypersensitive [...] Read more.

Detailed crystal structures and ¹H-NMR characteristics of some alkylaminephthalimides, including dendritic polyphthalimides, are reported. These investigations were undertaken in order to obtain a better understanding of the relationship between solid-state supramolecular interactions, their persistence in solution and associated dynamics of magnetically hypersensitive phthalimide aromatic AA'BB'-AA'XX' proton NMR resonances. Some alkylamine phthalimides feature folded molecular geometries, which we attribute to n-π interactions among proximal amine-phthalimide sites; those alkylamine-phthalimides that have no possibility for such interactions feature fully extended phthalimide functionalities. Accordingly, alkylamine phthalimide compounds with folded solid-state geometries feature solvent and temperature dependent hypersensitive AA'BB'-AA'XX' ¹H-NMR line profiles, which we attribute to the n-π interactions. Luminescence of Eu³⁺(⁵D0) and Tb³⁺(⁵D₄) states show well defined metal ion environments in their complexes with dendritic phthalimides, as well as relatively weak phthalimide-lanthanide(III) interactions. Full article

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29 KiB

Open AccessArticle

Selective Nitration of Aromatic Compounds with Bismuth Subnitrate and Thionyl Chloride

by Hussni A. Muathen

Molecules 2003, 8(7), 593-598; https://doi.org/10.3390/80700593 - 15 Jul 2003

Cited by 37 | Viewed by 13142

Abstract

Bismuth subnitrate/thionyl chloride have been found to be an efficient combination of reagents for nitration of a wide range of aromatic compounds in dichloromethane. Phenols, in particular, were easily mononitrated and dinitrated with the reagents by controlling the stoichiometry, Full article

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170 KiB

Open AccessArticle

Preparation and Crystal Structure of (1S, 5S, 7S, 8R)-8-Hydroxy-7-phenyl-2,6-dioxabicyclo[3.3.0]octan-3-one

by Vratislav Langer, Dalma Gyepesová, Marian Koman, Peter Kapitán, Matej Babjak, Tibor Gracza and Miroslav Koóš

Molecules 2003, 8(7), 599-606; https://doi.org/10.3390/80700599 - 15 Jul 2003

Cited by 2 | Viewed by 8570

Abstract

The absolute configuration at two newly formed stereogenic centres (5S, 7S) during the key steps of the total synthesis of naturally occuring goniothalesdiol was established by single-crystal X-ray diffraction analysis relative to stereocentres (1S, 8R) of the title compound (alternatively named 3,6-anhydro-2-deoxy-6-phenyl-L-ido-1,4-hexonolactone, C [...] Read more.

The absolute configuration at two newly formed stereogenic centres (5S, 7S) during the key steps of the total synthesis of naturally occuring goniothalesdiol was established by single-crystal X-ray diffraction analysis relative to stereocentres (1S, 8R) of the title compound (alternatively named 3,6-anhydro-2-deoxy-6-phenyl-L-ido-1,4-hexonolactone, C₁₂H₁₂O₄). The conformation of both 5-membered lactone and furanose fused rings is also discussed. Full article

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