Home About us Contact
|
Home About us Contact | ||
|
|
||
Useful Building Blocks (useful + building_block)
Selected AbstractsAlkoxy-5-nitrosopyrimidines: Useful Building Block for the Generation of Biologically Active CompoundsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 20 2010Antonio Marchal Abstract Several alkoxy-5-nitrosopyrimidines were synthesised and high regioselective and sequential nucleophilic aromatic substitution of methoxy groups in 2-amino-4,6-dimethoxy-5-nitrosopyrimidine was observed. The approach was applied to the synthesis of valuable polyfunctionalised aminopyrimidines capable of mimicking fused heterobicyclic derivatives of biological interest. In addition, new compounds were evaluated as antivirals and their usefulness as synthetic intermediates was demonstrated. [source] 2-Aminothiabutadiene as Useful Building Block in the Synthesis of 2-Aminothiopyrans and 2-Aminothiophenes.CHEMINFORM, Issue 45 2004Aelig Robin Abstract For Abstract see ChemInform Abstract in Full Text. [source] Highly Enantioselective Synthesis of 3-Hydroxy-2-methylpropanoic Acid Esters Through Ruthenium-SYNPHOS®-Catalyzed Hydrogenation: Useful Building Blocks for the Synthetic Community.CHEMINFORM, Issue 46 2007Severine Jeulin Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Fluorination of ,,,-Dichlorosulfides: Access to gem-Difluorothioethers as Useful Building Blocks.CHEMINFORM, Issue 40 2003Sonia Gouault Abstract For Abstract see ChemInform Abstract in Full Text. [source] Reinvestigation of Mucohalic Acids, Versatile and Useful Building Blocks for Highly Functionalized ,,,-Unsaturated ,-Butyrolactones.CHEMINFORM, Issue 17 2003Ji Zhang Abstract For Abstract see ChemInform Abstract in Full Text. [source] N -Unsubstituted and N -Arylated Fulleropyrrolidines: New Useful Building Blocks for C60 Functionalization,CHINESE JOURNAL OF CHEMISTRY, Issue 9 2006Chen-Hua Tong Abstract Two series of stable and soluble fulleropyrrolidines have been prepared from the reactions of C60, glycine or its N -arylated derivatives and aliphatic aldehydes or ketones in refluxing toluene or chlorobenzene. The new C60 derivatives represent new useful building blocks for further preparation of more funcionalized C60 derivatives. [source] Hydrazonoyl halides: Useful building blocks for the synthesis of arylazoheterocyclesJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 4 2003Ahmad Sami Shawali First page of article [source] Synthesis of an Enantiomerically Pure Building Block for the Synthesis of Hydroporphyrins,EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 2 2007Genevieve Etornam Adukpo Abstract The enantiomerically pure pyrrolidine diester 4 is a useful building block for the synthesis of chiral hydroporphyrin compounds. Treatment of optically active aromatic amines with bislactone 5 gave pairs of N -alkylated lactam-lactone diastereomers 6 and 8. These diastereomers were separated by MPL chromatography and in the case of 8 they could be debenzylated to yield the enantiomerically pure lactam-lactone 7 and its enantiomer. The (,)-lactam-lactone enantiomer 7 was further transformed into building block 4.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] An ,-hydrazinoalkylphosphonate as building block for novel N -phosphonoalkylheterocyclesHETEROATOM CHEMISTRY, Issue 4 2003Zai-Guo Li ,-Hydrazinoalkylphosphonate 3 is a useful building block for the syntheses of novel N -phosphonoalkylheterocycles. N -phosphonoalkylpyrazoles 8 and 9 were prepared by the cyclization reaction of 3 with multifunctioned ethenes 5 and 6 in ethanol under reflux. N -Phosphonoalkyltriazole 10 was synthesized from 3 with N -dimethylthiomethylene benzoyl amide 4 in ethanol under reflux. The structures were confirmed by IR, 1H NMR, mass spectroscopy, and elemental analysis. At the same time, the preparation of 4 was investigated. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:384,386, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10173 [source] Regio- and Stereo-selective Bioreduction of Diketo- n -butylphosphonate by Baker's YeastCHINESE JOURNAL OF CHEMISTRY, Issue 11 2002Ke Wang Abstract A regio- and stereo-selective reduction of diketo-n-butylphosphonates by baker's yeast was reported. The chemical yield and ee value of these reactions are highly dependent on the structure of substrates. The resulting optical active hydroxyalkanephosphonates can be used as chirons for the synthesis of polyfunctional organophosphorus compounds. As useful building block, a series of ,, ,-unsaturated ketones bearing chiral hydroxy group in addition to trifluoromethyl moiety was prepared via the Homer-Wadsworth-Emmons (HWE) reaction of the biotransformation products. [source] Precursors for Assembly of Supramolecules Containing Quadruply Bonded Cr24+ Units: Systematic Preparation of Cr2(formamidinate)n(acetate)4,n (n = 2,4)EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 22 2007F. Albert Cotton Abstract Four quadruply bonded dichromium complexes with mixed-ligand sets, Cr2(formamidinate)n(acetate)4,n (n = 2,4), were synthesized from reactions of anhydrous Cr2(O2CCH3)4 and formamidinate anions. The Cr,Cr bond lengths fall in the range for "supershort" Cr,Cr bonds as they vary from 1.8897(5) Å to 2.012(1) Å. The distance variation depends on the presence or absence of weak axial interactions. Because formamidinate ligands are less labile than acetate groups, these compounds may be useful building blocks for the construction of neutral supramolecules having dichromium units linked by polydentate dianions.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Organocatalytic Asymmetric Synthesis of Protected ,,,-Diamino AcidsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 17 2009Zugui Shi Abstract In the presence of the readily available quinine-derived catalyst 4d, highly diastereo- and enantioselective Mannich reactions of tosyl-protected imines and ,-isothiocyanato imides proceeded to afford the protected ,,,-diamino acids, useful building blocks for natural products and biologically active compounds, in good to excellent yields. [source] Conformational analysis of thiopeptides: derivation of sp2 sulfur parameters for the CFF91 force fieldJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 10 2001Tran Trung Tran Abstract When a sulfur atom is used to substitute for the oxygen in peptide bonds, its bulkiness should restrict the conformational space available to an amino acid. This conformational restriction as well as the ability to confer resistance to enzymatic degradation in the body means that thio-substituted amino acids are potentially useful building blocks for drug design. To simulate the effects of thio substitution, force field parameters for sp2 sulfur are required. In this article, parameters for the thioamide group have been derived for the molecular mechanics CFF91 force field (available at http://www.ludwig.edu.au/archive/tran). The bond increment charges were obtained by fitting to ab initio charges and dipoles. The van der Waals parameters were obtained by fitting to high-resolution crystallographic data, and the nonbonded parameters were verified by comparing with experimentally derived lattice energy. The bonded parameters were derived by least-square fits to the ab initio calculated energy surfaces, i.e., conformational energy as well as their first and second derivatives of seven model thioamide molecules. When the sp2 sulfur parameters were tested on a set of seven X-ray crystallographic structures from the Cambridge Structural Database, they satisfactorily reproduced the bond lengths, bond angles, torsional angles, and nonbonded distances of all the crystal structures. © 2001 John Wiley & Sons, Inc. J Comput Chem 22: 1010,1025, 2001 [source] Preparation, characterization and biological activities of novel ferrocenyl-substituted azaheterocycle compoundsAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 3 2003Jian-Xin Fang Abstract ,-Haloacetylferrocene and ,-triazolylacetylferrocene have been prepared from acetylferrocene and they have proved to be useful building blocks for the synthesis of ferrocenyl propenone. Two new types of ferrocenyl vinyl triazole compound, (Z,E)-ferrocenyl-[1-(1,2,4-triazol-1-yl)-2-phenyl]-vinyl-ones, have been synthesized and their structures characterized by crystal X-ray diffraction analysis. It has been shown for the first time that ferrocene, as an organometallic compound, has been introduced into bioactive triazole compounds in search of potent bioactive substances. Their biological activities are also discussed. Copyright © 2003 John Wiley & Sons, Ltd. [source] Byproduct-Catalyzed Four-Component Reactions of Aldehydes with Hexamethyldisilazane, Chloroformates, and Nucleophiles in Acetonitrile Leading to Protected Primary Amines, ,-Amino Esters, and ,-Amino KetonesCHEMISTRY - A EUROPEAN JOURNAL, Issue 2 2010Bai-Ling Yang Abstract Multicomponent reactions are a very powerful tool for the construction of complex organic molecules by using readily available starting materials. While most of the multicomponent reactions discovered so far consist of three components, the reactions with four or more components remain sparse. We have successfully developed several four-component reactions using a catalytic amount of water as a hydrolyzing agent to decompose byproduct chlorotrimethylsilane (TMSCl) to yield secondary byproduct HCl that serves as a catalyst. In the presence of 40,mol,% of water, the four-component reaction of aldehydes with hexamethyldisilazane (HMDS), chloroformates, and silylated nucleophiles proceeds smoothly at room temperature to give a range of protected primary amines in moderate to excellent yields. Importantly, a wide variety of protic carbon nucleophiles, such as ,-keto esters, ,-diketones, and ketones, have further been explored as suitable substrates for the synthesis of protected ,-amino esters and ,-amino ketones that are useful building blocks for various pharmaceuticals and natural products. These four-component reactions proceed through a pathway of tandem nitrogen protection/imine formation/imine addition, and the decomposition of byproduct TMSCl, generated in the first step of nitrogen protection, with water results in the formation of secondary byproduct HCl, a strong Brønsted acid that catalyzes the following imine formation/imine addition. Taking advantage of the fact that alcohols or phenols are also able to decompose byproduct TMSCl to yield secondary byproduct HCl, no catalyst is needed at all for the four-component reactions with aldehydes bearing hydroxy groups. [source] Highly Active Catalysts for the Telomerization of Crude Glycerol with 1,3-ButadieneCHEMSUSCHEM CHEMISTRY AND SUSTAINABILITY, ENERGY & MATERIALS, Issue 3 2008Regina Palkovits Dr. The chain gang: Crude glycerol, a by-product in the production of biodiesel, can be telomerized with 1,3-butadiene to form C8 -chain ethers. The development of suitable catalyst systems for the direct telomerization of crude glycerol at the biodiesel plant provides a route to useful building blocks from cheap starting materials for commercially valuable products such as detergents and surfactants. [source] N -Unsubstituted and N -Arylated Fulleropyrrolidines: New Useful Building Blocks for C60 Functionalization,CHINESE JOURNAL OF CHEMISTRY, Issue 9 2006Chen-Hua Tong Abstract Two series of stable and soluble fulleropyrrolidines have been prepared from the reactions of C60, glycine or its N -arylated derivatives and aliphatic aldehydes or ketones in refluxing toluene or chlorobenzene. The new C60 derivatives represent new useful building blocks for further preparation of more funcionalized C60 derivatives. [source] | ||||||||||||||||||||||