The Experts below are selected from a list of 312 Experts worldwide ranked by ideXlab platform
Yukiko Kato - One of the best experts on this subject based on the ideXlab platform.
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use of a solid supported coupling reagent for a selective Phosphitylation of the primary alcohol of n2 isobutyryl 2 deoxy or 2 o methyl guanosine
Tetrahedron Letters, 2006Co-Authors: Ivan Zlatev, Yukiko Kato, Albert Meyer, Jean-jacques Vasseur, François MorvanAbstract:Abstract We have developed a 5′-regioselective Phosphitylation of 3′,5′-OH-guanosine derivatives thanks to a solid-supported coupling reagent with either a standard or a bulky phosphine. A 5′-Phosphitylation up to a 95% selectivity was obtained with a quantitative conversion of starting nucleoside. After oxidation into thionophosphotriester or phosphotriester by means of solid-supported oxidizers, the 5′-phosphorylated N 2 - i -Bu-2′-OMe guanosines were isolated in good yields (70–80%).
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highly chemo and regioselective Phosphitylation of unprotected 2 deoxyribonucleosides
Tetrahedron Letters, 2006Co-Authors: Yukiko Kato, Natsuhisa Oka, Takeshi WadaAbstract:Abstract We have developed the chemo- and regioselective Phosphitylation of unprotected 2′-deoxyribonucleosides by the use of di- tert -butyl N , N -diethylphosphoramidite, a sterically hindered phosphoramidite. Both N/O- and primary hydroxy group-selectivities were simultaneously achieved, and the selectivity for the 5′-hydroxy groups was up to 97% regardless of the base moiety of the 2′-deoxyribonucleosides. The 3′-O-isomers and the 5′-O-isomers were easily separated by silica gel column chromatography or crystallization to give the pure 2′-deoxyribonucleoside 5′-phosphites in moderate to good yields.
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Use of a solid-supported coupling reagent for a selective Phosphitylation of the primary alcohol of N2-isobutyryl-2′-deoxy or 2′-O-methyl guanosine
Tetrahedron Letters, 2006Co-Authors: Ivan Zlatev, Yukiko Kato, Albert Meyer, Jean-jacques Vasseur, François MorvanAbstract:Abstract We have developed a 5′-regioselective Phosphitylation of 3′,5′-OH-guanosine derivatives thanks to a solid-supported coupling reagent with either a standard or a bulky phosphine. A 5′-Phosphitylation up to a 95% selectivity was obtained with a quantitative conversion of starting nucleoside. After oxidation into thionophosphotriester or phosphotriester by means of solid-supported oxidizers, the 5′-phosphorylated N 2 - i -Bu-2′-OMe guanosines were isolated in good yields (70–80%).
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Highly chemo- and regioselective Phosphitylation of unprotected 2′-deoxyribonucleosides
Tetrahedron Letters, 2006Co-Authors: Yukiko Kato, Natsuhisa Oka, Takeshi WadaAbstract:Abstract We have developed the chemo- and regioselective Phosphitylation of unprotected 2′-deoxyribonucleosides by the use of di- tert -butyl N , N -diethylphosphoramidite, a sterically hindered phosphoramidite. Both N/O- and primary hydroxy group-selectivities were simultaneously achieved, and the selectivity for the 5′-hydroxy groups was up to 97% regardless of the base moiety of the 2′-deoxyribonucleosides. The 3′-O-isomers and the 5′-O-isomers were easily separated by silica gel column chromatography or crystallization to give the pure 2′-deoxyribonucleoside 5′-phosphites in moderate to good yields.
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Highly chemo- and regioselective Phosphitylation of 2'-deoxyribonucleosides.
Nucleic Acids Symposium Series, 2003Co-Authors: Takeshi Wada, Yukiko Kato, Kazuhiko SaigoAbstract:We developed a novel method for the highly chemo- and regioselective Phosphitylation of the 5'-hydroxy group of 2'-deoxyribonuleosides with bis(O-tert-butyl) N,N-diethylphosphoramidite. The tert-butyl groups introduced in the thymidine 5'-O-phosphite and 2'-deoxycytidine 5'-O-phosphite were simultaneously removed within 5 min by treatment with trimethylsilyl triflate in acetonitrile to give the corresponding H-phosphonate monoesters without any side reactions.
François Morvan - One of the best experts on this subject based on the ideXlab platform.
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use of a solid supported coupling reagent for a selective Phosphitylation of the primary alcohol of n2 isobutyryl 2 deoxy or 2 o methyl guanosine
Tetrahedron Letters, 2006Co-Authors: Ivan Zlatev, Yukiko Kato, Albert Meyer, Jean-jacques Vasseur, François MorvanAbstract:Abstract We have developed a 5′-regioselective Phosphitylation of 3′,5′-OH-guanosine derivatives thanks to a solid-supported coupling reagent with either a standard or a bulky phosphine. A 5′-Phosphitylation up to a 95% selectivity was obtained with a quantitative conversion of starting nucleoside. After oxidation into thionophosphotriester or phosphotriester by means of solid-supported oxidizers, the 5′-phosphorylated N 2 - i -Bu-2′-OMe guanosines were isolated in good yields (70–80%).
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Use of a solid-supported coupling reagent for a selective Phosphitylation of the primary alcohol of N2-isobutyryl-2′-deoxy or 2′-O-methyl guanosine
Tetrahedron Letters, 2006Co-Authors: Ivan Zlatev, Yukiko Kato, Albert Meyer, Jean-jacques Vasseur, François MorvanAbstract:Abstract We have developed a 5′-regioselective Phosphitylation of 3′,5′-OH-guanosine derivatives thanks to a solid-supported coupling reagent with either a standard or a bulky phosphine. A 5′-Phosphitylation up to a 95% selectivity was obtained with a quantitative conversion of starting nucleoside. After oxidation into thionophosphotriester or phosphotriester by means of solid-supported oxidizers, the 5′-phosphorylated N 2 - i -Bu-2′-OMe guanosines were isolated in good yields (70–80%).
Arthur J Ragauskas - One of the best experts on this subject based on the ideXlab platform.
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Phosphitylation and quantitative 31p nmr analysis of partially substituted biodiesel glycerols
Fuel, 2009Co-Authors: Mate Nagy, Brian J Kerr, Cherie Ziemer, Arthur J RagauskasAbstract:The main step during biodiesel production is the catalytic transesterification of triglycerides. Glycerol and fatty acids are by-products of the biodiesel production and considered as contaminants in the final product. By selectively measuring the amount of fatty acids and glycerol with different substitution levels, the yield of this step and the quality of the final biodiesel can be determined. This study examines the application of Phosphitylation of glycerol hydroxyl groups with 2-chloro-4,4,5,5-tetramethyl-1,3,2-dioxaphospholane followed by P-31 NMR analysis to provide a rapid quantitative analytical technique for the determination of substitution patterns on partially esterified glycerols, alcohols and the detection of fatty acids. P-31 NMR chemical shift data was established with a series mono and di-substituted esters of glycerol, fatty acids and alcohols, then utilized to characterize commercial glycerol and biodiesel samples. (C) 2009 Elsevier Ltd. All rights reserved.
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Rapid quantitative analytical tool for characterizing the preparation of biodiesel.
The journal of physical chemistry. A, 2009Co-Authors: Mate Nagy, Marcus Foston, Arthur J RagauskasAbstract:A novel qualitative method has been developed for the determination of the various types of hydroxyl groups present in biodiesel production streams. The use of 2-chloro-4,4,5,5-tetramethyl-1,3,2-dioxaphospholane as a Phosphitylation reagent for quantitative P-31 NMR analysis of the hydroxyl groups in biodiesel process samples has been fully, developed. This experimental protocol allows for rapid analysis of biodiesel mixtures Of alcohols, fatty acids, glycerol, and mono- and disubstituted glycerides. Characteristic chemical shift ranges were developed with model compounds and used to fully characterize the conversion of triglyceride samples to biodiesel for two commercial production processes.
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quantitative nmr analysis of partially substituted biodiesel glycerols
Journal of Biobased Materials and Bioenergy, 2009Co-Authors: Mate Nagy, Teresa L Alleman, Thomas J Dyer, Arthur J RagauskasAbstract:Phosphitylation of hydroxyl groups in biodiesel samples with 2-chloro-4,4,5,5-tetramethyl-1,3,2-dioxaphospholane followed by P-31-NMR analysis provides a rapid quantitative analytical technique for the determination of substitution patterns on partially esterified glycerols. The unique P-31-NMR chemical shift data was established with a series mono and di-substituted fatty acid esters of glycerol and then utilized to characterize an industrial sample of partially processed biodiesel.
Ivan Zlatev - One of the best experts on this subject based on the ideXlab platform.
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use of a solid supported coupling reagent for a selective Phosphitylation of the primary alcohol of n2 isobutyryl 2 deoxy or 2 o methyl guanosine
Tetrahedron Letters, 2006Co-Authors: Ivan Zlatev, Yukiko Kato, Albert Meyer, Jean-jacques Vasseur, François MorvanAbstract:Abstract We have developed a 5′-regioselective Phosphitylation of 3′,5′-OH-guanosine derivatives thanks to a solid-supported coupling reagent with either a standard or a bulky phosphine. A 5′-Phosphitylation up to a 95% selectivity was obtained with a quantitative conversion of starting nucleoside. After oxidation into thionophosphotriester or phosphotriester by means of solid-supported oxidizers, the 5′-phosphorylated N 2 - i -Bu-2′-OMe guanosines were isolated in good yields (70–80%).
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Use of a solid-supported coupling reagent for a selective Phosphitylation of the primary alcohol of N2-isobutyryl-2′-deoxy or 2′-O-methyl guanosine
Tetrahedron Letters, 2006Co-Authors: Ivan Zlatev, Yukiko Kato, Albert Meyer, Jean-jacques Vasseur, François MorvanAbstract:Abstract We have developed a 5′-regioselective Phosphitylation of 3′,5′-OH-guanosine derivatives thanks to a solid-supported coupling reagent with either a standard or a bulky phosphine. A 5′-Phosphitylation up to a 95% selectivity was obtained with a quantitative conversion of starting nucleoside. After oxidation into thionophosphotriester or phosphotriester by means of solid-supported oxidizers, the 5′-phosphorylated N 2 - i -Bu-2′-OMe guanosines were isolated in good yields (70–80%).
Takeshi Wada - One of the best experts on this subject based on the ideXlab platform.
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Highly chemo- and regioselective Phosphitylation of 2’- deoxyri bon ucleosides
2016Co-Authors: Takeshi Wada, Yukiko Kat, Kazuhiko SaigoAbstract:We developed a novel method for the highly chemo-and regioselective Phosphitylation of the 5’-hydroxy group of 2’-deoxyribonuleosides with bis(0-tert-butyl) N,N-diethylphosphoramidite. The tert-butyl groups introduced in the thymidine 5’-O-phosphite and 2’-deoxycytidine 5’-O-phosphite were simultaneously removed within 5 min by treatment with trimethylsilyl triflate in acetonitrile to give the corresponding H-phosphonate monoesters without any side reactions
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Solid-phase synthesis of oligodeoxyribonucleotides without base protection utilizing O-selective reaction of oxazaphospholidine derivatives.
Nucleosides nucleotides & nucleic acids, 2010Co-Authors: Natsuhisa Oka, Yukihiro Maizuru, Mamoru Shimizu, Takeshi WadaAbstract:A study on the development of a novel method to synthesize oligodeoxyribonucleotides without base protection is described. We found that nucleoside 3'-O-oxazaphospholidine derivatives exclusively react with the hydroxy group of nucleosides in the presence of unprotected nucleobase amino groups. Since the O-chemoselectivity of the oxazaphospholidine derivatives is likely due to their ring structure, which allows the regeneration of the oxazaphospholidine derivatives from the corresponding base Phosphitylation adducts via an intramolecular recyclization, the method is expected to be compatible with any kinds of acidic activators.
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highly chemo and regioselective Phosphitylation of unprotected 2 deoxyribonucleosides
Tetrahedron Letters, 2006Co-Authors: Yukiko Kato, Natsuhisa Oka, Takeshi WadaAbstract:Abstract We have developed the chemo- and regioselective Phosphitylation of unprotected 2′-deoxyribonucleosides by the use of di- tert -butyl N , N -diethylphosphoramidite, a sterically hindered phosphoramidite. Both N/O- and primary hydroxy group-selectivities were simultaneously achieved, and the selectivity for the 5′-hydroxy groups was up to 97% regardless of the base moiety of the 2′-deoxyribonucleosides. The 3′-O-isomers and the 5′-O-isomers were easily separated by silica gel column chromatography or crystallization to give the pure 2′-deoxyribonucleoside 5′-phosphites in moderate to good yields.
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Highly chemo- and regioselective Phosphitylation of unprotected 2′-deoxyribonucleosides
Tetrahedron Letters, 2006Co-Authors: Yukiko Kato, Natsuhisa Oka, Takeshi WadaAbstract:Abstract We have developed the chemo- and regioselective Phosphitylation of unprotected 2′-deoxyribonucleosides by the use of di- tert -butyl N , N -diethylphosphoramidite, a sterically hindered phosphoramidite. Both N/O- and primary hydroxy group-selectivities were simultaneously achieved, and the selectivity for the 5′-hydroxy groups was up to 97% regardless of the base moiety of the 2′-deoxyribonucleosides. The 3′-O-isomers and the 5′-O-isomers were easily separated by silica gel column chromatography or crystallization to give the pure 2′-deoxyribonucleoside 5′-phosphites in moderate to good yields.
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Highly chemo- and regioselective Phosphitylation of 2'-deoxyribonucleosides.
Nucleic Acids Symposium Series, 2003Co-Authors: Takeshi Wada, Yukiko Kato, Kazuhiko SaigoAbstract:We developed a novel method for the highly chemo- and regioselective Phosphitylation of the 5'-hydroxy group of 2'-deoxyribonuleosides with bis(O-tert-butyl) N,N-diethylphosphoramidite. The tert-butyl groups introduced in the thymidine 5'-O-phosphite and 2'-deoxycytidine 5'-O-phosphite were simultaneously removed within 5 min by treatment with trimethylsilyl triflate in acetonitrile to give the corresponding H-phosphonate monoesters without any side reactions.
