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Molecules, Volume 4, Issue 1 (January 1999) – 5 articles , Pages 1-51, Article M91

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Short Note
N-Benzotriazol-1-yl-methyl-1,2,3,4-tetrahydroisoquinoline
by Cornelia Locher, Sara Baldey and Naseem Peerzada
Molecules 1999, 4(1), M91; https://doi.org/10.3390/M91 - 22 Feb 1999
Cited by 2 | Viewed by 3231
Abstract
Benzotriazole-mediated heteroalkylations have been explored for many synthetic pathways.[...] Full article
(This article belongs to the Section Molbank Section of Molecules, 1997-2001)
452 KiB  
Article
Polarization by the effect of a small torsional change in the benzothiazole (A)-benzobisthiazole (B) oligomer A-B13-A
by Francisco Torrens, José Sánchez-Marín and Ignacio Nebot-Gil
Molecules 1999, 4(1), 28-51; https://doi.org/10.3390/40100028 - 12 Feb 1999
Cited by 10 | Viewed by 9494
Abstract
We use a method for the calculation of the molecular dipole ( μ ) and quadrupole (θ ) moments and dipole-dipole (α ), dipole-quadrupole ( A) and quadrupole-quadrupole (C ) polarizabilities which we have successfully applied to the benzothiazole (A)-benzobisthiazole (B) linear oligomer [...] Read more.
We use a method for the calculation of the molecular dipole ( μ ) and quadrupole (θ ) moments and dipole-dipole (α ), dipole-quadrupole ( A) and quadrupole-quadrupole (C ) polarizabilities which we have successfully applied to the benzothiazole (A)-benzobisthiazole (B) linear oligomer A-B13-A. Two model rotational isomers have been characterized: (1) the fully-planar (000) conformation; and (2) a rotational isomer with each unit rotated in the range 1 - 10° in the same direction (+++). For isomer 000, μ is smaller than for +++. The calculation of α, A and C has been carried out by the interacting induced dipoles polarization model that calculates tensor effective anisotropic point polarizabilities (method of Applequist et al.). The values of A are specially sensitive to μ which varies under rotation. This fact explains the great values of Ax,xx for the +++ polar isomer. It is found that small torsional changes can enhance solubility by a clear increasing of the hydrophilic accessible surface area. However, the torsion of the oligomer varies the value of μ and so modifies α, C , and, specially, A. For conformer +++, polarization effects occur even when each unit is rotated only f = 1°. The observed effect is an increase in μ and, hence, in α , C , and, specially, A. Full article
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Article
An Efficient, Self-Protecting Route to Dimethyl 4-Amino-4-[2-(methoxycarbonyl)ethyl]-heptanedioate HCl
by Sally Henrie and Rita S. K. Majerle
Molecules 1999, 4(1), 13-15; https://doi.org/10.3390/40100013 - 09 Feb 1999
Viewed by 6142
Abstract
A method to reduce the nitro moiety in dimethyl 4-nitro-4-[1-[2(methoxycarbonyl)ethyl]]heptanedioate using a T-1 Raney nickel catalyst in an acidic environment is reported. The method avoids facile lactam formation. Full article
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63 KiB  
Article
Chemical Property Calculation through JavaScript and Applications in QSAR
by Hanqing Wu
Molecules 1999, 4(1), 16-27; https://doi.org/10.3390/40100016 - 08 Feb 1999
Cited by 13 | Viewed by 7773
Abstract
The inorganic property (I) and organic property (O) values of general organic groups are re-proposed here. Both I and O values of drug and biological molecules or groups can be calculated based on their common group values. The calculation can be performed easily [...] Read more.
The inorganic property (I) and organic property (O) values of general organic groups are re-proposed here. Both I and O values of drug and biological molecules or groups can be calculated based on their common group values. The calculation can be performed easily on-line through JavaScript. Similar calculation can be done for the drug and biological molecular group electronegativity (X) according to the author's published paper. The calculation of lipophilicity (π or logP) parameter of (macro)molecules (like proteins) can also be performed on-line through JavaScript. Two equations expressed with I and O are provided here to define the hydrophobicity of each amino acid. The correlations of inorganic property and organic property values with other parameters are also discussed. These calculated parameters combined with other parameters can be used for QSAR studies in some drug molecules. Full article
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88 KiB  
Review
A Straightforward Route to Enantiopure Pyrrolizidines and Indolizidines by Cycloaddition to Pyrroline N-Oxides Derived from the Chiral Pool
by Andrea Goti, Stefano Cicchi, Franca M. Cordero, Valentina Fedi and Alberto Brandi
Molecules 1999, 4(1), 1-12; https://doi.org/10.3390/40100001 - 22 Dec 1998
Cited by 43 | Viewed by 11688
Abstract
Enantiomerically pure, five membered cyclic nitrones, easily obtained in large amounts from protected hydroxyacids and aminoacids such as D- and L-tartaric, L-malic, and L-aspartic acids, give cycloaddition reactions with a good diastereocontrol. The adducts of L-malic and L-aspartic acids derived from addition of [...] Read more.
Enantiomerically pure, five membered cyclic nitrones, easily obtained in large amounts from protected hydroxyacids and aminoacids such as D- and L-tartaric, L-malic, and L-aspartic acids, give cycloaddition reactions with a good diastereocontrol. The adducts of L-malic and L-aspartic acids derived from addition of nitrones to dimethyl maleate and g-crotonolactone were easily converted into enantiopure pyrrolizidinones, which can be transformed into polyhydroxypyrrolidines or polyhydroxypyrrolizidines, both interesting compounds as potential glycosidase inhibitors. The method is suitable for natural products synthesis as exemplified by a straightforward and convenient access to the pyrrolizidine alkaloid necine base (–)-hastanecine, as well as to indolizidine alkaloids, i.e. (+)- lentiginosine. Full article
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