Here, the synthesis, photophysical characterization, and application of an ew size-expanded thymine nucleoside, diox T,i sd escribed. diox T has desirable qualities as aT surrogate, including excellent quantum yield (0.36) and high environmental sensitivity.W hen incorporatedi nto singleand double-stranded DNA, diox T showede xcellent photophysical characteristics including ahighquantum yield (average 0.20), and unlike BgQ, demonstrated dependenceo n neighboring bases withouts ignificantd estabilizationof the duplex. Interestingly,t he matched base pair of adenine (A) and diox T has the unique property that it exhibits higher fluorescence than mismatched base pairs, and diox T has selfquenching effects. As one example of the possible applications of thesep romising features, single nucleoside polymorphism typing is demonstrated for discrimination of Ab y using diox T.T he results suggestt hat diox T can be used for a broad range of applications in chemical biology.[a] S.Calculations were carried out with the B3LYP density functional method and 6-31G* basis set. The HOMO energy of each nucleobase was calculated by DFT (B3LYP/6-31G*) at the optimized geometry by using the Spartan "16 program. A = 9-methyladenine, T = 1-methylthymine, G = 9-methylguanine, C = 1-methylcytosine.
An ovel approach to the direct construction of tricyclic nitrogen heterocycles based on gold-catalyzed cascade cyclization of aminoallenynes is described. The expected biscyclization reaction of hydroxyisobutyryl-protected aminoallenynes was efficiently promoted by ac atalytic amount of BrettPhosAuNTf 2 in the presence of iPrOH to produce 1,2dihydrobenzo[cd]indole derivatives in good yields.W hen the reaction was combined with Friedel-Crafts acylation or palladium-catalyzed N-arylation, the resulting tricyclic products were efficiently converted into nitrogen-containing polycyclic aromatic compounds (N-PACs) with highly conjugated p-electron systems.Anewly obtained hexacyclic indolium salt showed characteristic concentration-dependent absorption and emission properties. Scheme 1. Gold(I)-catalyzed reactions of diynes and related compounds proceedingvia vinyl cation intermediates.
A gold‐catalyzed cascade cyclization of naphthalene‐tethered allenynes gave strained fused phenanthrene derivatives. The reaction proceeds through the nucleophilic reaction of an alkyne with the activated allene to generate a vinyl cation intermediate, followed by arylation with a tethered naphthalene ring to form the 4H‐cyclopenta[def]phenanthrene (CPP) scaffold. When using aryl‐substituted substrates on the alkyne terminus, the gold‐catalyzed reaction produced dibenzofluorene derivatives along with the CPP derivatives. Selective formation of CPP and dibenzofluorene derivatives depending on the reaction conditions is also presented.
An ovel approach to the direct construction of tricyclic nitrogen heterocycles based on gold-catalyzed cascade cyclization of aminoallenynes is described. The expected biscyclization reaction of hydroxyisobutyryl-protected aminoallenynes was efficiently promoted by ac atalytic amount of BrettPhosAuNTf 2 in the presence of iPrOH to produce 1,2dihydrobenzo[cd]indole derivatives in good yields.W hen the reaction was combined with Friedel-Crafts acylation or palladium-catalyzed N-arylation, the resulting tricyclic products were efficiently converted into nitrogen-containing polycyclic aromatic compounds (N-PACs) with highly conjugated p-electron systems.Anewly obtained hexacyclic indolium salt showed characteristic concentration-dependent absorption and emission properties. Scheme 1. Gold(I)-catalyzed reactions of diynes and related compounds proceedingvia vinyl cation intermediates.
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