The Experts below are selected from a list of 726 Experts worldwide ranked by ideXlab platform
Libiao Han - One of the best experts on this subject based on the ideXlab platform.
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alcohol based michaelis arbuzov reaction an efficient and environmentally benign method for c p o bond formation
Green Chemistry, 2018Co-Authors: Xu Zhang, Hongen Cao, Libiao HanAbstract:The famous Michaelis–Arbuzov reaction is extensively used both in the laboratory and industry to manufacture tons of widely-used organophosphoryl compounds every year. However, this method and the modified Michaelis–Arbuzov reactions developed recently still have some limitations. We now report a new alcohol-version of the Michaelis–Arbuzov reaction that can provide an efficient and environmentally-benign method to address the problems of the known Michaelis–Arbuzov reactions. That is, a wide range of alcohols can readily react with phosphites, phosphonites, and phosphinites to give all the three kinds of phosphoryl compounds (phosphonates, Phosphinates, and phosphine oxides) using an n-Bu4NI-catalyzed efficient C–P(O) bond formation reaction. This general method can also be easily scaled up and used for further synthetic transformations in one pot.
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Hydrophosphorylation of Alkynes Catalyzed by Palladium: Generality and Mechanism
2018Co-Authors: Tieqiao Chen, Chang-qiu Zhao, Libiao HanAbstract:We carried out a comprehensive study on the generality, scope, limitations, and mechanism of the palladium-catalyzed hydrophosphorylation of alkynes with P(O)–H compounds (i.e., H-phosphonates, H-Phosphinates, secondary phosphine oxides, and hypophosphinic acid). For H-phosphonates, Pd/dppp was the best catalyst. Both aromatic and aliphatic alkynes, with a variety of functional groups, were applicable to produce the Markovnikov adducts in high yields with high regioselectivity. Aromatic alkynes showed higher reactivity than aliphatic alkynes. Terminal alkynes reacted faster than internal alkynes. Sterically crowded H-phosphonates disfavored the addition. For H-Phosphinates and secondary phosphine oxides, Pd/dppe/Ph2P(O)OH was the catalyst of choice, which led to highly regioselective formation of the Markovnikov adducts. By using Pd(PPh3)4 as the catalyst, hypophosphinic acid added to terminal alkynes to give the corresponding Markovnikov adducts. Phosphinic acids, phosphonic acid, and its monoester were not applicable to this palladium-catalyzed hydrophosphorylation. Mechanistic studies showed that, with a terminal alkyne, (RO)2P(O)H reacted, like a Brønsted acid, to selectively generate the α-alkenylpalladium intermediate via hydropalladation. On the other hand, Ph(RO)P(O)H and Ph2P(O)H gave a mixture of α- and β-alkenylpalladium complexes. In the presence of Ph2P(O)OH, hydropalladation with this acid took place first to selectively generate the α-alkenylpalladium intermediate. A subsequent ligand exchange with a P(O)H compound gave the phosphorylpalladium intermediate which produced the Markovnikov adduct via reductive elimination. Related intermediates in the catalytic cycle were isolated and characterized
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Efficient Pd-Catalyzed Dehydrogenative Coupling of P(O)H with RSH: A Precise Construction of P(O)–S Bonds
2016Co-Authors: Yueyue Zhu, Tieqiao Chen, Shigeru Shimada, Libiao HanAbstract:A Pd-catalyzed dehydrogenative phosphorylation of thiols is developed. A variety of thiols dehydrogenatively couple readily with all three kinds of P(O)–H compounds, i.e., H-phosphonates, H-Phosphinates, and secondary phosphine oxides, providing a general access to the valuable phosphorothioates including the P-chiral compounds. A plausible mechanism is proposed
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chloroform based atherton todd type reactions of alcohols and thiols with secondary phosphine oxides generating phosphinothioates and Phosphinates
RSC Advances, 2015Co-Authors: Tieqiao Chen, Yuta Saga, Libiao HanAbstract:Chloroform-based Atherton–Todd-type reactions of alcohols and thiols with secondary phosphine oxides, generating phosphinothioates and Phosphinates, respectively, are described. Various valuable phosphinothioates and Phosphinates including those with functional groups are readily prepared under mild reaction conditions.
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preparation of enantiomerically pure α hydroxyl Phosphinates via hydrophosphorylation of aldehydes with h phosphinate
Tetrahedron-asymmetry, 2014Co-Authors: Yongming Sun, Chang-qiu Zhao, Lijuan Liu, Fanjie Meng, He Zhang, Lijun Sun, Meiju Niu, Shuwen Gong, Libiao HanAbstract:Abstract The hydrophosphorylation of aldehydes with a P-stereogenic H-phosphinate was realized by heating two compounds in a neat state or catalyzed by a base, to afford P-retention α-hydroxyl Phosphinates. The (SP,SC) and other diastereomers were isolated, and their structures were confirmed by NMR spectroscopy and crystallography.
Reinhard Pell - One of the best experts on this subject based on the ideXlab platform.
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Tailoring of Integrin Ligands: Probing the Charge Capability of the Metal Ion-Dependent Adhesion Site
Journal of medicinal chemistry, 2012Co-Authors: Markus Bollinger, Florian Manzenrieder, Roman Kolb, Alexander Bochen, Stefanie Neubauer, Luciana Marinelli, Vittorio Limongelli, Ettore Novellino, Georg Moessmer, Reinhard PellAbstract:Intervention in integrin-mediated cell adhesion and integrin signaling pathways is an ongoing area of research in medicinal chemistry and drug development. One key element in integrin–ligand interaction is the coordination of the bivalent cation at the metal ion-dependent adhesion site (MIDAS) by a carboxylic acid function, a consistent feature of all integrin ligands. With the exception of the recently discovered hydroxamic acids, all bioisosteric attempts to replace the carboxylic acid of integrin ligands failed. We report that Phosphinates as well as monomethyl phosphonates represent excellent isosters, when introduced into integrin antagonists for the platelet integrin αIIbβ3. The novel inhibitors exhibit in vitro and ex vivo activities in the low nanomolar range. Steric and charge requirements of the MIDAS region were unraveled, thus paving the way for an in silico prediction of ligand activity and in turn the rational design of the next generation of integrin antagonists.
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Tailoring of Integrin Ligands: Probing the Charge Capability of the Metal Ion-Dependent Adhesion Site
2012Co-Authors: Markus Bollinger, Florian Manzenrieder, Roman Kolb, Alexander Bochen, Stefanie Neubauer, Luciana Marinelli, Vittorio Limongelli, Ettore Novellino, Georg Moessmer, Reinhard PellAbstract:Intervention in integrin-mediated cell adhesion and integrin signaling pathways is an ongoing area of research in medicinal chemistry and drug development. One key element in integrin–ligand interaction is the coordination of the bivalent cation at the metal ion-dependent adhesion site (MIDAS) by a carboxylic acid function, a consistent feature of all integrin ligands. With the exception of the recently discovered hydroxamic acids, all bioisosteric attempts to replace the carboxylic acid of integrin ligands failed. We report that Phosphinates as well as monomethyl phosphonates represent excellent isosters, when introduced into integrin antagonists for the platelet integrin αIIbβ3. The novel inhibitors exhibit in vitro and ex vivo activities in the low nanomolar range. Steric and charge requirements of the MIDAS region were unraveled, thus paving the way for an in silico prediction of ligand activity and in turn the rational design of the next generation of integrin antagonists
Markus Bollinger - One of the best experts on this subject based on the ideXlab platform.
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Tailoring of Integrin Ligands: Probing the Charge Capability of the Metal Ion-Dependent Adhesion Site
Journal of medicinal chemistry, 2012Co-Authors: Markus Bollinger, Florian Manzenrieder, Roman Kolb, Alexander Bochen, Stefanie Neubauer, Luciana Marinelli, Vittorio Limongelli, Ettore Novellino, Georg Moessmer, Reinhard PellAbstract:Intervention in integrin-mediated cell adhesion and integrin signaling pathways is an ongoing area of research in medicinal chemistry and drug development. One key element in integrin–ligand interaction is the coordination of the bivalent cation at the metal ion-dependent adhesion site (MIDAS) by a carboxylic acid function, a consistent feature of all integrin ligands. With the exception of the recently discovered hydroxamic acids, all bioisosteric attempts to replace the carboxylic acid of integrin ligands failed. We report that Phosphinates as well as monomethyl phosphonates represent excellent isosters, when introduced into integrin antagonists for the platelet integrin αIIbβ3. The novel inhibitors exhibit in vitro and ex vivo activities in the low nanomolar range. Steric and charge requirements of the MIDAS region were unraveled, thus paving the way for an in silico prediction of ligand activity and in turn the rational design of the next generation of integrin antagonists.
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Tailoring of Integrin Ligands: Probing the Charge Capability of the Metal Ion-Dependent Adhesion Site
2012Co-Authors: Markus Bollinger, Florian Manzenrieder, Roman Kolb, Alexander Bochen, Stefanie Neubauer, Luciana Marinelli, Vittorio Limongelli, Ettore Novellino, Georg Moessmer, Reinhard PellAbstract:Intervention in integrin-mediated cell adhesion and integrin signaling pathways is an ongoing area of research in medicinal chemistry and drug development. One key element in integrin–ligand interaction is the coordination of the bivalent cation at the metal ion-dependent adhesion site (MIDAS) by a carboxylic acid function, a consistent feature of all integrin ligands. With the exception of the recently discovered hydroxamic acids, all bioisosteric attempts to replace the carboxylic acid of integrin ligands failed. We report that Phosphinates as well as monomethyl phosphonates represent excellent isosters, when introduced into integrin antagonists for the platelet integrin αIIbβ3. The novel inhibitors exhibit in vitro and ex vivo activities in the low nanomolar range. Steric and charge requirements of the MIDAS region were unraveled, thus paving the way for an in silico prediction of ligand activity and in turn the rational design of the next generation of integrin antagonists
Irishi N N Namboothiri - One of the best experts on this subject based on the ideXlab platform.
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enantioselective synthesis of α amino γ sulfonyl phosphonates with a tetrasubstituted chiral α carbon via quinine squaramide catalyzed michael addition of nitrophosphonates to vinyl sulfones
Advanced Synthesis & Catalysis, 2013Co-Authors: Kalisankar Bera, Irishi N N NamboothiriAbstract:α-Nitro-γ-sulfonyl phosphonates with a key tetrasubstituted chiral α-carbon center have been synthesized for the first time in high yield and enantioselectivity through a quinine-squaramide-catalyzed conjugate addition of α-nitro phosphonates to aryl vinyl sulfones. Representative examples presented here for the transformation of nitrosulfonyl phosphonates to aminosulfonyl phosphonates, alkylation at the α-position of the sulfonyl group followed by desulfonation and scale-up of the conjugate addition highlight the practical applications of the methodology.
Marc Taillefer - One of the best experts on this subject based on the ideXlab platform.
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A Copper-Catalyzed Variant of the Michaelis-Arbuzov Reaction
ChemCatChem, 2014Co-Authors: Jorge Ballester, Jérémie Gatignol, Guntran Schmidt, Carole Alayrac, Annie-claude Gaumont, Marc TailleferAbstract:As part of our studies on copper-catalyzed arylation of nucleophiles, we report on Michaelis-Arbuzov reactions with a novel catalytic system, featuring a copper(I) salt as precatalyst without any additional ligand. This procedure is an interesting alternative to the use of expensive and toxic transition metals (nickel, palladium) traditionally used as catalysts in Michaelis-Arbuzov reactions. Our approach allows the synthesis from triethylphosphite, diethyl aryl phosphonite, and diaryl ethylphosphinite of various aryl phosphonates, aryl Phosphinates, and aryl phosphine oxides, respectively. These families of compounds are essential owing to their respective importance in bioorganic and medical chemistry, their applicability as flame retardants, and their usability in coordination chemistry and catalysis.