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Key Reaction (key + reaction)
Terms modified by Key Reaction Selected AbstractsChemInform Abstract: Synthesis of Conjugated Enynes by Assembly of Three Components, Ketones, Chloromethyl p-Tolyl Sulfoxide, and Acetylenes, with the Magnesium Carbenoid 1,2-CC Insertion as the Key Reaction.CHEMINFORM, Issue 18 2010Hideki Saitoh Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: A New Synthesis of ,,,-Unsaturated Esters from Three Components, Aldehydes, Chloromethyl p-Tolyl Sulfoxide, and tert-Butyl Acetate, via Magnesium Carbenoid 1,2-CH and 1,2-CC Insertion as the Key Reaction.CHEMINFORM, Issue 2 2008Tsuyoshi Satoh 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 of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] A Versatile Synthesis, Including Asymmetric Synthesis, of Bicyclo[n.1.0]alkanes from Cyclic Ketones via the Magnesium Carbenoid 1,3-CH Insertion as a Key Reaction.CHEMINFORM, Issue 2 2007Tsuyoshi Satoh 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] Synthesis of (R)-6,7-Dihydro-5-HETE Lactone and (S)-6,7-Dihydro-5-HETE Lactone by Using Novel Yeast Reduction as a Key Reaction.CHEMINFORM, Issue 7 2003Satoshi Yamauchi Abstract For Abstract see ChemInform Abstract in Full Text. [source] ChemInform Abstract: A New Method for Synthesis of Allenes, Including an Optically Active Form, from Aldehydes and Alkenyl Aryl Sulfoxides by Sulfoxide,Metal Exchange as the Key Reaction and an Application to a Total Synthesis of Male Bean Weevil Sex Attractant (XXV).CHEMINFORM, Issue 32 2002Tsuyoshi Satoh Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] A Formal Total Synthesis of (±)-1,13-HerbertenediolEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 3 2004Adusuhilli Srikrishna Abstract A formal total synthesis of (±)-1,13-herbertenediol, employing a ring-closing metathesis reaction of the 4-arylhepta-1,6-diene-4-carboxylate 15 as the key reaction, is described. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] DPPH (=,2,2-Diphenyl-1-picrylhydrazyl,=,2,2-Diphenyl-1-(2,4,6-trinitrophenyl)hydrazyl) Radical-Scavenging Reaction of Protocatechuic Acid Esters (=,3,4-Dihydroxybenzoates) in Alcohols: Formation of Bis-alcohol AdductHELVETICA CHIMICA ACTA, Issue 4 2006Shizuka Saito Abstract Protocatechuic acid esters (=,3,4-dihydroxybenzoates) scavenge ca. 5,equiv. of radical in alcoholic solvents, whereas they consume only 2,equiv. of radical in nonalcoholic solvents. While the high radical-scavenging activity of protocatechuic acid esters in alcoholic solvents as compared to that in nonalcoholic solvents is due to a nucleophilic addition of an alcohol molecule at C(2) of an intermediate o -quinone structure, thus regenerating a catechol (=,benzene-1,2-diol) structure, it is still unclear why protocatechuic acid esters scavenge more than 4,equiv. of radical (C(2) refers to the protocatechuic acid numbering). Therefore, to elucidate the oxidation mechanism beyond the formation of the C(2) alcohol adduct, 3,4-dihydroxy-2-methoxybenzoic acid methyl ester (4), the C(2) MeOH adduct, which is an oxidation product of methyl protocatechuate (1) in MeOH, was oxidized by the DPPH radical (=,2,2-diphenyl-1-picrylhydrazyl) or o -chloranil (=,3,4,5,6-tetrachlorocyclohexa-3,5-diene-1,2-dione) in CD3OD/(D6)acetone 3,:,1). The oxidation mixtures were directly analyzed by NMR. Oxidation with both the DPPH radical and o -chloranil produced a C(2),C(6) bis-methanol adduct (7), which could scavenge additional 2,equiv. of radical. Calculations of LUMO electron densities of o -quinones corroborated the regioselective nucleophilic addition of alcohol molecules with o -quinones. Our results strongly suggest that the regeneration of a catechol structure via a nucleophilic addition of an alcohol molecule with a o -quinone is a key reaction for the high radical-scavenging activity of protocatechuic acid esters in alcoholic solvents. [source] An Arabidopsis porB porC double mutant lacking light-dependent NADPH:protochlorophyllide oxidoreductases B and C is highly chlorophyll-deficient and developmentally arrestedTHE PLANT JOURNAL, Issue 2 2003Geneviève Frick Summary A key reaction in the biosynthesis of chlorophylls (Chls) a and b from cyanobacteria through higher plants is the strictly light-dependent reduction of protochlorophyllide (Pchlide) a to chlorophyllide (Chlide) a. Angiosperms, unlike other photosynthetic organisms, rely exclusively upon this mechanism to reduce Pchlide and hence require light to green. In Arabidopsis, light-dependent Pchlide reduction is mediated by three structurally related but differentially regulated NADPH:Pchlide oxidoreductases, denoted as PORA, PORB, and PORC. The PORA and PORB genes, but not PORC, are strongly expressed early in seedling development. In contrast, expression of PORB and PORC, but not PORA, is observed in older seedlings and adult plants. We have tested the hypothesis that PORB and PORC govern light-dependent Chl biosynthesis throughout most of the plant development by identifying porB and porC mutants of Arabidopsis, the first higher plant por mutants characterized. The porB-1 and porC-1 mutants lack the respective POR transcripts and specific POR isoforms because of the interruption of the corresponding genes by a derivative of the maize Dissociation (Ds) transposable element. Single por mutants, grown photoperiodically, display no obvious phenotypes at the whole plant or chloroplast ultrastructural levels, although the porB-1 mutant has less extensive etioplast inner membranes. However, a light-grown porB-1 porC-1 double mutant develops a seedling-lethal xantha phenotype at the cotyledon stage, contains only small amounts of Chl a, and possesses chloroplasts with mostly unstacked thylakoid membranes. PORB and PORC thus seem to play redundant roles in maintaining light-dependent Chl biosynthesis in green plants, and are together essential for growth and development. [source] ChemInform Abstract: Alternative Route to the Diisocyanate Building Block 1,4-Diisocyanato-4-methylpentane (DIMP).CHEMINFORM, Issue 43 2010Matthew C. Davis Abstract Diisocyanate (VIII) is regioselectively synthesized starting from isobutyronitrile in six steps using a double Curtius rearrangement as the key reaction. [source] Tetrahedral Oligothiophenes; Synthesis, X-ray Analysis, and Optoelectronic Properties of Highly Symmetrical, 3D-Branched OligothiophenesCHEMISTRY - AN ASIAN JOURNAL, Issue 12 2008Kouzou Matsumoto Dr. Abstract Tetrakis(bithienyl)methane and tetrakis(terthienyl)methane have been synthesized from tetrakis(2-thienyl)methane by use of Suzuki,Miyaura coupling as a key reaction. Their trimethylsilyl (TMS) derivatives are also synthesized. X-ray analysis reveals that each oligothiophene moiety tends to adopt anti -conformations and show relatively small torsion angles between the adjacent thiophene rings. While the longest absorption maxima of these tetrakis(oligothienyl)methanes exhibit only a slight bathochromic shift compared to the corresponding linear oligothiophene derivative, tetrakis(bithienyl)methane and its TMS derivative exhibit an appreciable red-shift in their fluorescence spectra. The intramolecular interaction between thienyl groups of tetrakis(2-thienyl)methane is supported by DFT calculation. [source] Studies Directed Towards the Total Synthesis of (,)-DictyostatinEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 11 2010Jhillu S. Yadav Abstract The stereoselective synthesis of the three major fragments (C1,C9, C10,C17, and C19,C26) of an antimitotic marine macrolide, (,)-dictyostatin, has been achieved with a desymmetrization strategy and Oppolzer syn and anti aldol protocols as the key reactions. Takai olefination and Sonogashira coupling reactions were successfully utilized to establish the 2Z,4E -dienoate portion of the C1,C9 fragment and Stille coupling for the Z -diene core of C19,C26. [source] Numerical study on NO formation in CH4,O2,N2 diffusion flame diluted with CO2INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 2 2005Dong-Jin Hwang Abstract Numerical study with momentum-balanced boundary conditions has been conducted to grasp chemical effects of added CO2, to either fuel- or oxidizer-side on flame structure and NO emission behaviour in CH4,O2,N2 diffusion flames. Cautious investigation is made for the comparison among the behaviours of principal chain branching and important H-removal key reactions. This describes successfully the reason why flame temperatures for fuel-side dilution are higher than those for oxidizer-side dilution. The role of the principal chain branching reaction is also recognized to be important even in the change of major flame structure caused by chemical effects. The importantly contributing reaction steps to NO production are examined. The reduced production rates of thermal NO and prompt NO due to chemical effects are much more remarkable for fuel-side dilution. It is also found that the reaction step, H+NO+M=HNO+M plays a decisive role of the formation and destruction of prompt NO. Copyright © 2005 John Wiley & Sons, Ltd. [source] Biologically Active Compounds through Catalysis: Efficient Synthesis of N -(Heteroarylcarbonyl)- N,-(arylalkyl)piperazinesCHEMISTRY - A EUROPEAN JOURNAL, Issue 3 2004Kamal Kumar Dr. Abstract A practical route for the synthesis of new biologically active 5-HT2,A receptor antagonists has been developed. In only three catalytic steps, this class of central nervous system (CNS) active compounds can be synthesized efficiently with high diversity. As the initial step, an anti -Markovnikov addition of amines to styrenes provides an easy route to N -(arylalkyl)piperazines, which constitute the core structure of the active molecules. Here, base-catalyzed hydroamination reactions of styrenes with benzylated piperazine proceeded in high yield even at room temperature. After catalytic debenzylation, the free amines were successfully carbonylated with different aromatic and heteroaromatic halides and carbon monoxide to yield the desired compounds in good to excellent yields. The two key reactions, base-catalyzed hydroamination of styrenes and palladium-catalyzed aminocarbonylation of haloarenes/heterocycles, showed tolerance towards various functional groups, thereby demonstrating the potential to synthesize a wide variety of new derivatives of this promising class of pharmaceuticals. [source] | ||||||||||||||||||||||