Synthesis of Positional Isomers of Structured Lipids with Lipases as Biocatalysts

1998 ◽  
pp. 46-72 ◽  
Author(s):  
Casimir Akoh ◽  
Ki-Teak Lee ◽  
Lydia Fomuso
Keyword(s):  
Structured Lipids ◽  
Positional Isomers

Aromaticity in heterocyclic molecules containing divalent sulfur

1988 ◽  
Vol 53 (9) ◽  
pp. 2023-2054 ◽  
Author(s):  
Milan Randić ◽  
Sonja Nikolić ◽  
Nenad Trinajstić
Keyword(s):  
Sulfur Atom ◽  
Positional Isomers ◽  
Heterocyclic Molecules ◽  
Resonance Energies ◽  
Conjugated Circuits ◽  
Divalent Sulfur

The conjugated circuits model is applied to heterocycles containing divalent sulfur. A novel parametrization is introduced for 4n + 2 and 4n conjugated circuits containing a single sulfur atom. The relative aromatic stabilities of a number of heterocyclic systems containing divalent sulfur are studied. Comparison is made whenever possible with earlier reported resonance energies of these compounds, obtained by using Huckel MO and SCF π-MO models, and appropriate reference structures. Special attention is given to positional isomers. An explanation of the differences amongst such isomers is given.

Some 2-substitution derivatives of 5-(4-oxo-6-hydroxy-3,4-dihydro-5-pyrimidinyl)pentanoic acid

1983 ◽  
Vol 48 (1) ◽  
pp. 304-311 ◽  
Author(s):  
Jiří Křepelka ◽  
Jan Beneš ◽  
Vladimír Pouzar ◽  
Jaroslav Vachek ◽  
Jiří Holubek
Keyword(s):  
Nitrile Group ◽  
Antineoplastic Activity ◽  
Carboxyl Group ◽  
Positional Isomers ◽  
Pentanoic Acid ◽  
Pharmacological Tests ◽  
Derivatives Of

Condensation of triethyl ester of 1,1,5-pentanetricarboxylic acid (XI) with substituted guanidines XXII - XXIX gave acids II - IX, which were converted into esters XI - XIX. The acid II and the ester XI were obtained as mixtures of positional isomers. Analogously, condensation of the triester XXI with dicyanodiamide gave rise to acid X, whose nitrile group, under conditions of esterification of a carboxyl group, produced iminoether XX. In pharmacological tests for antineoplastic activity the compounds prepared exhibited weaker efficacy than 5-(2-amino-6-hydroxy-4-oxo-3,4-dihydro-5-pyrimidinyl)pentanoic acid (I), employed as standard.

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