The Experts below are selected from a list of 210 Experts worldwide ranked by ideXlab platform
James L. Gleason - One of the best experts on this subject based on the ideXlab platform.
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density functional theory guided design of exo selective dehydroalanine dienophiles for application toward the synthesis of palau amine
Journal of Organic Chemistry, 2008Co-Authors: Tim Cernak, James L. GleasonAbstract:Diels−Alder cycloadditions of dehydroalanine derivatives with cyclopentadiene, applicable to the synthesis of palau'amine, were investigated experimentally and using DFT computations at the B3LYP/6-31G* level of theory. Oxazolone and thiohydantoin dienophiles were found to be significantly more reactive than hydantoins or dehydroalanine methyl esters. The increased reactivity of the thiohydantoins relative to hydantoins is attributed to increased conjugation of nitrogen lone pairs into the Thiocarbonyl Group. β-Substitution greatly decelerates the cycloadditions due to steric interactions in the transition states outweighing any electronic activation by chlorine. Hydantoins and thiohydantoins were found to be exo-selective, while the corresponding oxazolones and dehydroalanines were unselective.
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Density functional theory guided design of exo-selective dehydroalanine dienophiles for application toward the synthesis of palau'amine.
The Journal of organic chemistry, 2007Co-Authors: Tim Cernak, James L. GleasonAbstract:Diels-Alder cycloadditions of dehydroalanine derivatives with cyclopentadiene, applicable to the synthesis of palau'amine, were investigated experimentally and using DFT computations at the B3LYP/6-31G* level of theory. Oxazolone and thiohydantoin dienophiles were found to be significantly more reactive than hydantoins or dehydroalanine methyl esters. The increased reactivity of the thiohydantoins relative to hydantoins is attributed to increased conjugation of nitrogen lone pairs into the Thiocarbonyl Group. beta-Substitution greatly decelerates the cycloadditions due to steric interactions in the transition states outweighing any electronic activation by chlorine. Hydantoins and thiohydantoins were found to be exo-selective, while the corresponding oxazolones and dehydroalanines were unselective.
Yusaku Suenaga - One of the best experts on this subject based on the ideXlab platform.
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an s s contact assembled tetranuclear copper i complex with sulfur rich ligand 4 5 ethylenedithio 1 3 dithiole 2 thione
Inorganica Chimica Acta, 1997Co-Authors: Megumu Munakata, Liangping Wu, Takayoshi Kurodasowa, Yusaku SuenagaAbstract:Abstract A copper(I) complex with 4,5-ethylenedithio-1,3-dithiole-2-thione (C 5 H 4 S 5 ), [Cu 4 I 4 (C 5 H 4 S 5 ) 4 ] ∞ , was synthesized and the molecular structure and packing were characterized crystallographically. The metal center is a stepped Cu 4 I 4 core coordinated by two ligands C 5 H 4 S 5 in different ways. One is bidentate coordinated through the Thiocarbonyl Group and the thioether Group and the other is monodentate coordinated only through Thiocarbonyl Group. The Cu 4 I 4 clusters are bridged by bidentate C 5 H 4 S 5 molecules to form one-dimensional polymeric chains along the c -axis, and these chains form a three-dimensional network linked by interchain S⋯S contacts. The shortest S⋯S contact distance is 3.257 (2) A. A crystal of the complex is triclinic with space Group P 1 , a=11.350(5) A , b=11.854(3) A , c=9.275(5) A , α=97.32(4)°, β=112.35(4)°, γ=67.67(2)°, V=1067.0(9) A 3 , Z=2, R=0.034, R w =0.051 .
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An S⋯S contact assembled tetranuclear copper(I) complex with sulfur-rich ligand, 4,5-ethylenedithio-1,3-dithiole-2-thione
Inorganica Chimica Acta, 1997Co-Authors: Jie Dai, Megumu Munakata, Takayoshi Kuroda-sowa, Yusaku SuenagaAbstract:Abstract A copper(I) complex with 4,5-ethylenedithio-1,3-dithiole-2-thione (C 5 H 4 S 5 ), [Cu 4 I 4 (C 5 H 4 S 5 ) 4 ] ∞ , was synthesized and the molecular structure and packing were characterized crystallographically. The metal center is a stepped Cu 4 I 4 core coordinated by two ligands C 5 H 4 S 5 in different ways. One is bidentate coordinated through the Thiocarbonyl Group and the thioether Group and the other is monodentate coordinated only through Thiocarbonyl Group. The Cu 4 I 4 clusters are bridged by bidentate C 5 H 4 S 5 molecules to form one-dimensional polymeric chains along the c -axis, and these chains form a three-dimensional network linked by interchain S⋯S contacts. The shortest S⋯S contact distance is 3.257 (2) A. A crystal of the complex is triclinic with space Group P 1 , a=11.350(5) A , b=11.854(3) A , c=9.275(5) A , α=97.32(4)°, β=112.35(4)°, γ=67.67(2)°, V=1067.0(9) A 3 , Z=2, R=0.034, R w =0.051 .
Robert S. Coleman - One of the best experts on this subject based on the ideXlab platform.
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Regeneration of 4-thio-2'-deoxyuridine residues in DNA.
Bioorganic & medicinal chemistry letters, 1999Co-Authors: Robert S. Coleman, Richard M. PiresAbstract:We report a facile, quantitative regeneration of the Thiocarbonyl Group from S-alkylated 4-thio-2'-deoxyuridine residues by treatment with NaSH within oligodeoxynucleotides.
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6 thio 2 deoxyinosine synthesis incorporation and evaluation as a postsynthetically modifiable base in oligonucleotides
Tetrahedron, 1997Co-Authors: Robert S. Coleman, John C Arthur, Jason L MccaryAbstract:Abstract The synthesis of 6-thio-2′-deoxyinosine (d S6 I) in a form suitably protected for solid-phase oligonucleotide synthesis is reported. This thionucleic acid was incorporated in high yield into short oligodeoxynucleotides, and the Thiocarbonyl Group could be modified by S-alkylation with complete chemoselectivity. The quantitation of incorporation and facile post-synthetic modification was demonstrated by enzymatic digestion and HPLC analysis, and the effect of covalent alkylation was determined by ΔT m measurements of the corresponding duplex oligonucleotides with dC as the complementary base.
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6-Thio-2′-deoxyinosine: Synthesis, incorporation, and evaluation as a postsynthetically modifiable base in oligonucleotides
Tetrahedron, 1997Co-Authors: Robert S. Coleman, John C Arthur, Jason L MccaryAbstract:Abstract The synthesis of 6-thio-2′-deoxyinosine (d S6 I) in a form suitably protected for solid-phase oligonucleotide synthesis is reported. This thionucleic acid was incorporated in high yield into short oligodeoxynucleotides, and the Thiocarbonyl Group could be modified by S-alkylation with complete chemoselectivity. The quantitation of incorporation and facile post-synthetic modification was demonstrated by enzymatic digestion and HPLC analysis, and the effect of covalent alkylation was determined by ΔT m measurements of the corresponding duplex oligonucleotides with dC as the complementary base.
Tim Cernak - One of the best experts on this subject based on the ideXlab platform.
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density functional theory guided design of exo selective dehydroalanine dienophiles for application toward the synthesis of palau amine
Journal of Organic Chemistry, 2008Co-Authors: Tim Cernak, James L. GleasonAbstract:Diels−Alder cycloadditions of dehydroalanine derivatives with cyclopentadiene, applicable to the synthesis of palau'amine, were investigated experimentally and using DFT computations at the B3LYP/6-31G* level of theory. Oxazolone and thiohydantoin dienophiles were found to be significantly more reactive than hydantoins or dehydroalanine methyl esters. The increased reactivity of the thiohydantoins relative to hydantoins is attributed to increased conjugation of nitrogen lone pairs into the Thiocarbonyl Group. β-Substitution greatly decelerates the cycloadditions due to steric interactions in the transition states outweighing any electronic activation by chlorine. Hydantoins and thiohydantoins were found to be exo-selective, while the corresponding oxazolones and dehydroalanines were unselective.
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Density functional theory guided design of exo-selective dehydroalanine dienophiles for application toward the synthesis of palau'amine.
The Journal of organic chemistry, 2007Co-Authors: Tim Cernak, James L. GleasonAbstract:Diels-Alder cycloadditions of dehydroalanine derivatives with cyclopentadiene, applicable to the synthesis of palau'amine, were investigated experimentally and using DFT computations at the B3LYP/6-31G* level of theory. Oxazolone and thiohydantoin dienophiles were found to be significantly more reactive than hydantoins or dehydroalanine methyl esters. The increased reactivity of the thiohydantoins relative to hydantoins is attributed to increased conjugation of nitrogen lone pairs into the Thiocarbonyl Group. beta-Substitution greatly decelerates the cycloadditions due to steric interactions in the transition states outweighing any electronic activation by chlorine. Hydantoins and thiohydantoins were found to be exo-selective, while the corresponding oxazolones and dehydroalanines were unselective.
Xiaohui Zhang - One of the best experts on this subject based on the ideXlab platform.
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nmr and uv studies of 4 thio 2 deoxyuridine and its derivatives
Molecules, 2011Co-Authors: Xiaohui ZhangAbstract:5-Substituted-4-thio-2’-deoxyuridine nucleosides have been chemically synthesized and studied by NMR and UV spectroscopy. The results have been analyzed and discussed in connection with the previous data. The imino proton signal and the carbon signal of the Thiocarbonyl Group in the 5-substituted-4-thio-2’-deoxyuridines were found to be at much lower field, offering a potential for monitoring these modified bases at the DNA level. All 4-thionucleosides have strong absorptions at around 340 nm and consequently would be useful as potential UVA-induced anticancer agents.
