نتایج جستجو برای: cn bond cleavage
تعداد نتایج: 126103 فیلتر نتایج به سال:
In contrast to the structurally and configurationally stable alkyl- or aryl-substituted cyclopropyl radical cations, cyclopropyl silyl ethers undergo spontaneous ring opening upon oxidation whereby the endocyclic C-C(O-TMS) bond is cleaved with remarkable selectivity. DFT calculations on 1-trimethylsilyloxybicyclo[4.1.0]heptane show that this selectivity arises from the topology of the potentia...
Disulfide bonds generally show only limited cleavage in positive ion mode collision activated dissociation (CAD). However, it has been emonstrated that a reverse situation exists in negative ion mode in which preferential S S and C S bond cleavage occurs. Here, we show that lectron detachment dissociation (EDD) and infrared multiphoton dissociation (IRMPD) of peptide anions containing disulfide...
The oxidative addition of cyclic ditelluride 1-oxa-5,6-ditelluraspirooctane, Te(2)C(5)H(8)O, to bis(triphenylphosphine)(norbornene)platinum(0), [Pt(PPh(3))(2)(eta(2)-nb)], and to [1,8-bis(diphenylphosphino)naphthalene](norbornene)platinum(0), [Pt(dppn)(eta(2)-nb)], lead to the formation of dinuclear and mononuclear tellurolato platinum(ii) complexes, respectively, as a consequence of Te-Te bond...
Zinc chlorochromate nonahydrate is easily prepared from the aqueous solution of chromium trioxide and zinc chloride in quantitative yield. This oxidant, in methylene chloride and at room temperature, oxidizes thiols to their disulfides. Acetals and thioacetals are deprotected to their corresponding carbonyl compounds. Sulfides are selectively converted to ther sulfoxides or sulfones. Arylox...
UNLABELLED Complete biodegradation of the abundant and persistent fluoroaromatics requires enzymatic cleavage of an arylic C-F bond, probably the most stable single bond of a biodegradable organic molecule. While in aerobic microorganisms defluorination of fluoroaromatics is initiated by oxygenases, arylic C-F bond cleavage has never been observed in the absence of oxygen. Here, an oxygen-indep...
Specific cleavage of RNA is catalysed by short oligodeoxynucleotides termed DNAzymes. DNAzymes consist of two binding arms that hybridize to a predetermined RNA sequence and a catalytic core that cleaves a phosphodiester bond held between the binding arms. DNAzymes are exemplified by the well-studied 10-23 DNAzyme, which compared with protein ribonucleases is highly specific, albeit slow. Here ...
Anodic oxidation of N-aryl-2,2-diphenylacetamides in acetonitrile undergoes three types of bond-cleavage, one between the benzylic carbon and the carbonyl group, the second between a carbonyl and 'N', and the third between the 'N' atom and aryl group. The selectivity of the cleavage and nature of emerged products is highly dependent on the nature of substituent attached to the aryl group. For e...
Conformational changes in the extradiscal regions of rhodopsin induced by illumination were investigated by modifying the visual pigment by mild treatment with cyanogen bromide prior to and after light exposure. Light induced an increased yield of cleavage of the Met bond 253-254 and a new cleavage at the Met bond 155-156 of the rhodopsin polypeptide chain. These residues, located at the beginn...
A Rh-catalyzed regiodivergent hydrosilylation of acyl aminocyclopropanes has been developed. Acyl aminocyclopropanes were reacted with hydrosilanes in the presence of Rh catalysts to afford ring-opened hydrosilylated adducts through carbon–carbon (C–C) bond cleavage of the cyclopropane ring. The regioselectivity of the addition of silanes (linear or branched) can be switched by changing the mon...
The electron shell structure of superheavy elements, i.e., elements with atomic number Z ≥ 104, is influenced by strong relativistic effects caused by the high Z. Early atomic calculations on element 112 (copernicium, Cn) and element 114 (flerovium, Fl) having closed and quasi-closed electron shell configurations of 6d(10)7s(2) and 6d(10)7s(2)7p1/2(2), respectively, predicted them to be noble-g...
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