Functionalized Derivatives (functionalized + derivative)

Distribution by Scientific Domains
Distribution within Chemistry


Selected Abstracts


The Superbase-Mediated Pairwise Substitution of the 2,2,- and 6,6,-Positions in a Biphenyl Derivative

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 5 2004
Manfred Schlosser
Abstract The superbasic mixture of butyllithium and potassium tert -butoxide is powerful enough to enable the double proton abstraction from one ortho and one ortho, position of 4,4,-di- tert -butylbiphenyl. In this way, a series of functionalized derivatives becomes readily accessible, among them 4,4,-di- tert -butylbiphenyldiyl-2,2,-dicarboxylic acid (2a) and 4,4,-di- tert -butylbiphenyl-2,2,-diol (2d). The latter compound can be subjected again to a superbase-promoted double metalation, thus giving rise to 2,2,,6,6,-tetrasubstituted biphenyl derivatives. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source]


Ab Initio Structure/Reactivity Investigations of Illudin-Based Antitumor Agents: A Model for Reaction in vivo

HELVETICA CHIMICA ACTA, Issue 12 2003
Laura
(Hydroxymethyl)acylfulvene (HMAF, irofulven; 4), a third-generation derivative of a natural product extracted from the mushroom Omphalotus illudens, is selectively toxic towards certain forms of malignant tumors. Conversion of HMAF and cognates to stable aromatic derivatives is triggered by thiol attack in vitro and in vivo. Quantum-chemical methods predict well the structure for several functionalized derivatives of irofulven as compared to known X-ray crystallographic structures. Computational reaction profiles for thiol attack and aromatic rearrangement of irofulven and illudin S, a toxin from which irofulven is derived, provide insight into HMAF's selectivity and toxicity. Methods used include hybrid density-functional theory (HDFT), HartreeFock (HF), and MøllerPlesset second-order perturbation theory (MP2). Solvent effects have been explored by means of the new continuum-solvation method, COSab, presented in an accompanying paper. [source]


Synthesis of the new adducts of imines and enamines with PH acids and their derivatives,

HETEROATOM CHEMISTRY, Issue 2 2009
Andrey A. Prishchenko
Nucleophilic or radical addition of esters of trivalent organophosphorus acids with PH fragments to various imines and enamines is proposed as convenient methods for the synthesis of new substituted aminomethyl organophosphorus compounds with three-, four-, and five-coordinated phosphorus. Also the new functionalized derivatives of these compounds with acyl and methanesulfonyl moieties are synthesized, and some properties of the obtained compounds are presented. © 2009 Wiley Periodicals, Inc. Heteroatom Chem 20:70,80, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20513 [source]


Synthesis of functionalized 2-trimethylsiloxy-substituted O -trimethylsilyl alkylphosphonites, their analogues, and derivatives

HETEROATOM CHEMISTRY, Issue 5 2008
Andrey A. Prishchenko
Nucleophilic addition of trimethylsilyl esters of tricoordinate organophosphorus acids to several functionalized alkylene oxides is proposed as convenient methods for the synthesis of new 2-trimethylsiloxysubstituted alkylphosphonites, their analogues, and derivatives. Also the new functionalized derivatives of these phosphonites, including amino, carboxy, or sulfo groups as well as certain properties of these compounds, which may be the important precursors of new functionalized 2-hydroxyalkylorganophosphorus acids, are presented. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:450,454, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20453 [source]


Synthesis of 2-substituted O,O -bis(trimethylsilyl) alkylphosphonites with aryl and heterocyclic fragments and their amino or amido derivatives

HETEROATOM CHEMISTRY, Issue 4 2008
Andrey A. Prishchenko
Free-radical addition of bis(trimethyl-siloxy)phosphine to various functionalized alkenes with aryl and heterocyclic fragments is proposed as a convenient procedure for the synthesis of new 2-substituted alkylphosphonites of corresponding structures. Also the new functionalized derivatives of these phosphonites, including various amino and amido groups as well as certain properties of these compounds, are presented. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:345,351, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20431 [source]


Synthesis of functionalized 1-trimethylsiloxy-substituted O -trimethylsilyl alkylphosphonites and their derivatives

HETEROATOM CHEMISTRY, Issue 4 2008
Andrey A. Prishchenko
Nucleophilic addition of trimethylsilyl esters of tricoordinate organophosphorus acids to various functionalized aldehydes with vinyl, aryl, and heterocyclic fragments is proposed as a convenient method for the synthesis of new 1-trimethylsiloxysubstituted alkylphosphonites and their derivatives at mild conditions. Also the new functionalized derivatives of these phosphonites, including amino groups as well as certain properties of these compounds as important precursors of new functionalized 1-hydroxyalkylorganophosphorus acids, are presented. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:352,359, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20430 [source]


Mechanism of the Asymmetric Sulfoxidation in the Esomeprazole Process: Effects of the Imidazole Backbone for the Enantioselection

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 6 2009
Muthu Seenivasaperumal
Abstract The asymmetric sulfoxidation reaction of imidazole-based prochiral sulfides was studied to explore the mechanistic details of the highly efficient esomeprazole process, which is one of the few industrial scale catalytic asymmetric procedures. The synthetic studies revealed that the smallest subunit governing the selectivity in the esomeprazole process is an imidazole ring. Thus, by using the esomeprazole procedure methyl imidazole sulfide could be oxidized as efficiently as its several functionalized derivatives, including pyrmetazol. However, alkylation of the imidazole nitrogen led to a major drop of the enantioselectivity. Our atmospheric pressure chemical ionization-mass spectrometry (APCI/MS) studies indicate that addition of small amounts of water to the reaction mixture facilitates the formation of mononuclear titanium species, which are the active catalytic intermediates of the selective oxidation reaction. One of the most important features of the esomeprazole procedure is that amine additives increase the enantioselectivity of the oxidation process. The NMR studies of the presumed reaction intermediates show that under catalytic conditions the amines are able to coordinate to titanium and dissociate the coordinated imidazole substrate. The density functional theory (DFT) modelling studies provided new insights in the mechanism of the asymmetric induction. It was found that the oxidation requires a lower activation energy if the imidazole sulfide precursor does not coordinate to titanium. Two possible reaction paths were explored for this out of sphere oxidation mechanism. The most important interaction governing the enantioselection is hydrogen bonding between the NH of the imidazole ring and the chiral tartrate ligand on titanium. Furthermore, the oxidation reaction imposes an important structural constraint to the TS structure involving a linear arrangement of the peroxide oxygens and the sulfur atom. This constraint and the N coordination of imidazole leads to a very strained structure for the inner sphere mechanism of the oxidation, which leads to a much higher activation barrier than the corresponding out of sphere process, and therefore it is unlikely. [source]


Synthesis and radioiodination of 7-(3,-ammoniopropyl)-7,8-dicarba- nido -undecaborate(-1), (ANC)

JOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 9 2004
Senait Ghirmai
Abstract Derivatives of nido -carborate have potential use in tumour targeting as hydrophilic boron-rich compounds for boron neutron capture therapy (BNCT) and as pendant groups for attachment of radiohalogens to tumour-seeking molecules. For this purpose, functionalized derivatives of nido -carborates that can be conjugated to biomolecules should be synthesized and evaluated. In this study, racemic 1, 7-(3,-ammoniopropyl)-7,8-dicarba- nido -undecaborate(-1) (acronym ANC) was obtained by degradation of the corresponding aminopropyl- o -carborane, which was synthesized in three steps from 1- tert -butyldimethylsilyl-2-(3-bromopropyl)- o -carborane, with sodium hydroxide in absolute ethanol. The racemate 1 was radioiodinated (125I) using the Chloramine-T method. Radio-TLC results showed that radiolabelling with 125I was achieved in a yield greater than 95%. Copyright © 2004 John Wiley & Sons, Ltd. [source]


Precursors of Biological Cofactors from Ultraviolet Irradiation of Circumstellar/Interstellar Ice Analogues

CHEMISTRY - A EUROPEAN JOURNAL, Issue 17 2005
Uwe J. Meierhenrich Priv.-Doz.
Abstract Biological cofactors include functionalized derivatives of cyclic tetrapyrrole structures that incorporate different metal ions. They build up structural partnerships with proteins, which play a crucial role in biochemical reactions. Porphyrin, chlorin, bacteriochlorin, and corrin are the basic structures of cofactors (heme, chlorophyll, bacteriochlorophyll, siroheme, F 430, and vitamin B12). Laboratory and theoretical work suggest that the molecular building blocks of proteins (,-amino acids) and nucleic acids (carbohydrates, purines, and pyrimidines) were generated under prebiotic conditions. On the other hand, experimental data on the prebiotic chemistry of cofactors are rare. We propose to search directly for the pathways of the formation of cofactors in the laboratory. Herein we report on the detection of N-heterocycles and amines in the room-temperature residue obtained after photo- and thermal processing of an interstellar ice analogue under high vacuum at 12 K. Among them, hexahydro-1,3,5-triazine and its derivatives, together with monopyrrolic molecules, are precursors of porphinoid cofactors. Hexahydropyrimidine was also detected. This is the first detection of these compounds in experiments simulating circumstellar/interstellar conditions. Except for 2-aminopyrrole and 2,4-diaminofuran, which were only found in 13C-labeled experiments, all the reported species were detected in both 12C- and 13C-labeled experiments, excluding contamination. The molecules reported here might be present in circumstellar/interstellar grains and cometary dust and could be detected by the Stardust and Rosetta missions. [source]