The Experts below are selected from a list of 78 Experts worldwide ranked by ideXlab platform
Alois Fürstner - One of the best experts on this subject based on the ideXlab platform.
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Interligand Interactions Dictate the Regioselectivity of trans-Hydrometalations and Related Reactions Catalyzed by [Cp*RuCl]. Hydrogen Bonding to a Chloride Ligand as a Steering Principle in Catalysis
Journal of the American Chemical Society, 2015Co-Authors: Stephan M. Rummelt, Karin Radkowski, Dragoş-adrian Roşca, Alois FürstnerAbstract:Reactions of internal alkynes with R3M–H (M = Si, Ge, Sn) follow an unconventional trans-addition mode in the presence of [Cp*Ru(MeCN)3]PF6 (1) as the catalyst; however, the regioselectivity is often poor with unsymmetrical substrates. This problem can be solved upon switching to a catalyst comprising a [Ru–Cl] bond, provided that the Acetylene Derivative carries a protic functional group. The R3M unit is then delivered with high selectivity to the alkyne-C atom proximal to this steering substituent. This directing effect originates from the ability of the polarized [Ru–Cl] bond to engage in hydrogen bonding with the protic substituent, which helps upload, activate, and lock the alkyne within the coordination sphere. An additional interligand contact of the chloride with the −MR3 center positions the incoming reagent in a matching orientation that translates into high regioselectivity. The proposed secondary interactions within the loaded catalyst are in line with a host of preparative and spectral data a...
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interligand interactions dictate the regioselectivity of trans hydrometalations and related reactions catalyzed by cp rucl hydrogen bonding to a chloride ligand as a steering principle in catalysis
Journal of the American Chemical Society, 2015Co-Authors: Stephan M. Rummelt, Karin Radkowski, Dragoş-adrian Roşca, Alois FürstnerAbstract:Reactions of internal alkynes with R3M-H (M = Si, Ge, Sn) follow an unconventional trans-addition mode in the presence of [Cp*Ru(MeCN)3]PF6 (1) as the catalyst; however, the regioselectivity is often poor with unsymmetrical substrates. This problem can be solved upon switching to a catalyst comprising a [Ru-Cl] bond, provided that the Acetylene Derivative carries a protic functional group. The R3M unit is then delivered with high selectivity to the alkyne-C atom proximal to this steering substituent. This directing effect originates from the ability of the polarized [Ru-Cl] bond to engage in hydrogen bonding with the protic substituent, which helps upload, activate, and lock the alkyne within the coordination sphere. An additional interligand contact of the chloride with the -MR3 center positions the incoming reagent in a matching orientation that translates into high regioselectivity. The proposed secondary interactions within the loaded catalyst are in line with a host of preparative and spectral data and with the structures of the novel ruthenium π-complexes 10 and 11 in the solid state. Moreover, the first X-ray structure of a [Ru(σ-stannane)] complex (12a) is presented, which indeed features peripheral Ru-Cl···MR3 contacts; this adduct also corroborates that alkyne trans-addition chemistry likely involves σ-complexes as reactive intermediates. Finally, it is discussed that interligand cooperativity might constitute a more general principle that extends to mechanistically distinct transformations. The presented data therefore make an interesting case for organometallic chemistry that provides inherently better results when applied to substrates containing unprotected rather than protected -OH, -NHR, or -COOH groups.
Stephan M. Rummelt - One of the best experts on this subject based on the ideXlab platform.
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Interligand Interactions Dictate the Regioselectivity of trans-Hydrometalations and Related Reactions Catalyzed by [Cp*RuCl]. Hydrogen Bonding to a Chloride Ligand as a Steering Principle in Catalysis
Journal of the American Chemical Society, 2015Co-Authors: Stephan M. Rummelt, Karin Radkowski, Dragoş-adrian Roşca, Alois FürstnerAbstract:Reactions of internal alkynes with R3M–H (M = Si, Ge, Sn) follow an unconventional trans-addition mode in the presence of [Cp*Ru(MeCN)3]PF6 (1) as the catalyst; however, the regioselectivity is often poor with unsymmetrical substrates. This problem can be solved upon switching to a catalyst comprising a [Ru–Cl] bond, provided that the Acetylene Derivative carries a protic functional group. The R3M unit is then delivered with high selectivity to the alkyne-C atom proximal to this steering substituent. This directing effect originates from the ability of the polarized [Ru–Cl] bond to engage in hydrogen bonding with the protic substituent, which helps upload, activate, and lock the alkyne within the coordination sphere. An additional interligand contact of the chloride with the −MR3 center positions the incoming reagent in a matching orientation that translates into high regioselectivity. The proposed secondary interactions within the loaded catalyst are in line with a host of preparative and spectral data a...
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interligand interactions dictate the regioselectivity of trans hydrometalations and related reactions catalyzed by cp rucl hydrogen bonding to a chloride ligand as a steering principle in catalysis
Journal of the American Chemical Society, 2015Co-Authors: Stephan M. Rummelt, Karin Radkowski, Dragoş-adrian Roşca, Alois FürstnerAbstract:Reactions of internal alkynes with R3M-H (M = Si, Ge, Sn) follow an unconventional trans-addition mode in the presence of [Cp*Ru(MeCN)3]PF6 (1) as the catalyst; however, the regioselectivity is often poor with unsymmetrical substrates. This problem can be solved upon switching to a catalyst comprising a [Ru-Cl] bond, provided that the Acetylene Derivative carries a protic functional group. The R3M unit is then delivered with high selectivity to the alkyne-C atom proximal to this steering substituent. This directing effect originates from the ability of the polarized [Ru-Cl] bond to engage in hydrogen bonding with the protic substituent, which helps upload, activate, and lock the alkyne within the coordination sphere. An additional interligand contact of the chloride with the -MR3 center positions the incoming reagent in a matching orientation that translates into high regioselectivity. The proposed secondary interactions within the loaded catalyst are in line with a host of preparative and spectral data and with the structures of the novel ruthenium π-complexes 10 and 11 in the solid state. Moreover, the first X-ray structure of a [Ru(σ-stannane)] complex (12a) is presented, which indeed features peripheral Ru-Cl···MR3 contacts; this adduct also corroborates that alkyne trans-addition chemistry likely involves σ-complexes as reactive intermediates. Finally, it is discussed that interligand cooperativity might constitute a more general principle that extends to mechanistically distinct transformations. The presented data therefore make an interesting case for organometallic chemistry that provides inherently better results when applied to substrates containing unprotected rather than protected -OH, -NHR, or -COOH groups.
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Interligand Interactions Dictate the Regioselectivity of trans-Hydrometalations and Related Reactions Catalyzed by [Cp*RuCl]. Hydrogen Bonding to a Chloride Ligand as a Steering Principle in Catalysis
2015Co-Authors: Stephan M. Rummelt, Karin Radkowski, Dragoş-adrian Roşca, Alois FürstnerAbstract:Reactions of internal alkynes with R3M–H (M = Si, Ge, Sn) follow an unconventional trans-addition mode in the presence of [Cp*Ru(MeCN)3]PF6 (1) as the catalyst; however, the regioselectivity is often poor with unsymmetrical substrates. This problem can be solved upon switching to a catalyst comprising a [Ru–Cl] bond, provided that the Acetylene Derivative carries a protic functional group. The R3M unit is then delivered with high selectivity to the alkyne-C atom proximal to this steering substituent. This directing effect originates from the ability of the polarized [Ru–Cl] bond to engage in hydrogen bonding with the protic substituent, which helps upload, activate, and lock the alkyne within the coordination sphere. An additional interligand contact of the chloride with the −MR3 center positions the incoming reagent in a matching orientation that translates into high regioselectivity. The proposed secondary interactions within the loaded catalyst are in line with a host of preparative and spectral data and with the structures of the novel ruthenium π-complexes 10 and 11 in the solid state. Moreover, the first X-ray structure of a [Ru(σ-stannane)] complex (12a) is presented, which indeed features peripheral Ru–Cl···MR3 contacts; this adduct also corroborates that alkyne trans-addition chemistry likely involves σ-complexes as reactive intermediates. Finally, it is discussed that interligand cooperativity might constitute a more general principle that extends to mechanistically distinct transformations. The presented data therefore make an interesting case for organometallic chemistry that provides inherently better results when applied to substrates containing unprotected rather than protected −OH, −NHR, or −COOH groups
Karin Radkowski - One of the best experts on this subject based on the ideXlab platform.
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Interligand Interactions Dictate the Regioselectivity of trans-Hydrometalations and Related Reactions Catalyzed by [Cp*RuCl]. Hydrogen Bonding to a Chloride Ligand as a Steering Principle in Catalysis
Journal of the American Chemical Society, 2015Co-Authors: Stephan M. Rummelt, Karin Radkowski, Dragoş-adrian Roşca, Alois FürstnerAbstract:Reactions of internal alkynes with R3M–H (M = Si, Ge, Sn) follow an unconventional trans-addition mode in the presence of [Cp*Ru(MeCN)3]PF6 (1) as the catalyst; however, the regioselectivity is often poor with unsymmetrical substrates. This problem can be solved upon switching to a catalyst comprising a [Ru–Cl] bond, provided that the Acetylene Derivative carries a protic functional group. The R3M unit is then delivered with high selectivity to the alkyne-C atom proximal to this steering substituent. This directing effect originates from the ability of the polarized [Ru–Cl] bond to engage in hydrogen bonding with the protic substituent, which helps upload, activate, and lock the alkyne within the coordination sphere. An additional interligand contact of the chloride with the −MR3 center positions the incoming reagent in a matching orientation that translates into high regioselectivity. The proposed secondary interactions within the loaded catalyst are in line with a host of preparative and spectral data a...
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interligand interactions dictate the regioselectivity of trans hydrometalations and related reactions catalyzed by cp rucl hydrogen bonding to a chloride ligand as a steering principle in catalysis
Journal of the American Chemical Society, 2015Co-Authors: Stephan M. Rummelt, Karin Radkowski, Dragoş-adrian Roşca, Alois FürstnerAbstract:Reactions of internal alkynes with R3M-H (M = Si, Ge, Sn) follow an unconventional trans-addition mode in the presence of [Cp*Ru(MeCN)3]PF6 (1) as the catalyst; however, the regioselectivity is often poor with unsymmetrical substrates. This problem can be solved upon switching to a catalyst comprising a [Ru-Cl] bond, provided that the Acetylene Derivative carries a protic functional group. The R3M unit is then delivered with high selectivity to the alkyne-C atom proximal to this steering substituent. This directing effect originates from the ability of the polarized [Ru-Cl] bond to engage in hydrogen bonding with the protic substituent, which helps upload, activate, and lock the alkyne within the coordination sphere. An additional interligand contact of the chloride with the -MR3 center positions the incoming reagent in a matching orientation that translates into high regioselectivity. The proposed secondary interactions within the loaded catalyst are in line with a host of preparative and spectral data and with the structures of the novel ruthenium π-complexes 10 and 11 in the solid state. Moreover, the first X-ray structure of a [Ru(σ-stannane)] complex (12a) is presented, which indeed features peripheral Ru-Cl···MR3 contacts; this adduct also corroborates that alkyne trans-addition chemistry likely involves σ-complexes as reactive intermediates. Finally, it is discussed that interligand cooperativity might constitute a more general principle that extends to mechanistically distinct transformations. The presented data therefore make an interesting case for organometallic chemistry that provides inherently better results when applied to substrates containing unprotected rather than protected -OH, -NHR, or -COOH groups.
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Interligand Interactions Dictate the Regioselectivity of trans-Hydrometalations and Related Reactions Catalyzed by [Cp*RuCl]. Hydrogen Bonding to a Chloride Ligand as a Steering Principle in Catalysis
2015Co-Authors: Stephan M. Rummelt, Karin Radkowski, Dragoş-adrian Roşca, Alois FürstnerAbstract:Reactions of internal alkynes with R3M–H (M = Si, Ge, Sn) follow an unconventional trans-addition mode in the presence of [Cp*Ru(MeCN)3]PF6 (1) as the catalyst; however, the regioselectivity is often poor with unsymmetrical substrates. This problem can be solved upon switching to a catalyst comprising a [Ru–Cl] bond, provided that the Acetylene Derivative carries a protic functional group. The R3M unit is then delivered with high selectivity to the alkyne-C atom proximal to this steering substituent. This directing effect originates from the ability of the polarized [Ru–Cl] bond to engage in hydrogen bonding with the protic substituent, which helps upload, activate, and lock the alkyne within the coordination sphere. An additional interligand contact of the chloride with the −MR3 center positions the incoming reagent in a matching orientation that translates into high regioselectivity. The proposed secondary interactions within the loaded catalyst are in line with a host of preparative and spectral data and with the structures of the novel ruthenium π-complexes 10 and 11 in the solid state. Moreover, the first X-ray structure of a [Ru(σ-stannane)] complex (12a) is presented, which indeed features peripheral Ru–Cl···MR3 contacts; this adduct also corroborates that alkyne trans-addition chemistry likely involves σ-complexes as reactive intermediates. Finally, it is discussed that interligand cooperativity might constitute a more general principle that extends to mechanistically distinct transformations. The presented data therefore make an interesting case for organometallic chemistry that provides inherently better results when applied to substrates containing unprotected rather than protected −OH, −NHR, or −COOH groups
Dragoş-adrian Roşca - One of the best experts on this subject based on the ideXlab platform.
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Interligand Interactions Dictate the Regioselectivity of trans-Hydrometalations and Related Reactions Catalyzed by [Cp*RuCl]. Hydrogen Bonding to a Chloride Ligand as a Steering Principle in Catalysis
Journal of the American Chemical Society, 2015Co-Authors: Stephan M. Rummelt, Karin Radkowski, Dragoş-adrian Roşca, Alois FürstnerAbstract:Reactions of internal alkynes with R3M–H (M = Si, Ge, Sn) follow an unconventional trans-addition mode in the presence of [Cp*Ru(MeCN)3]PF6 (1) as the catalyst; however, the regioselectivity is often poor with unsymmetrical substrates. This problem can be solved upon switching to a catalyst comprising a [Ru–Cl] bond, provided that the Acetylene Derivative carries a protic functional group. The R3M unit is then delivered with high selectivity to the alkyne-C atom proximal to this steering substituent. This directing effect originates from the ability of the polarized [Ru–Cl] bond to engage in hydrogen bonding with the protic substituent, which helps upload, activate, and lock the alkyne within the coordination sphere. An additional interligand contact of the chloride with the −MR3 center positions the incoming reagent in a matching orientation that translates into high regioselectivity. The proposed secondary interactions within the loaded catalyst are in line with a host of preparative and spectral data a...
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interligand interactions dictate the regioselectivity of trans hydrometalations and related reactions catalyzed by cp rucl hydrogen bonding to a chloride ligand as a steering principle in catalysis
Journal of the American Chemical Society, 2015Co-Authors: Stephan M. Rummelt, Karin Radkowski, Dragoş-adrian Roşca, Alois FürstnerAbstract:Reactions of internal alkynes with R3M-H (M = Si, Ge, Sn) follow an unconventional trans-addition mode in the presence of [Cp*Ru(MeCN)3]PF6 (1) as the catalyst; however, the regioselectivity is often poor with unsymmetrical substrates. This problem can be solved upon switching to a catalyst comprising a [Ru-Cl] bond, provided that the Acetylene Derivative carries a protic functional group. The R3M unit is then delivered with high selectivity to the alkyne-C atom proximal to this steering substituent. This directing effect originates from the ability of the polarized [Ru-Cl] bond to engage in hydrogen bonding with the protic substituent, which helps upload, activate, and lock the alkyne within the coordination sphere. An additional interligand contact of the chloride with the -MR3 center positions the incoming reagent in a matching orientation that translates into high regioselectivity. The proposed secondary interactions within the loaded catalyst are in line with a host of preparative and spectral data and with the structures of the novel ruthenium π-complexes 10 and 11 in the solid state. Moreover, the first X-ray structure of a [Ru(σ-stannane)] complex (12a) is presented, which indeed features peripheral Ru-Cl···MR3 contacts; this adduct also corroborates that alkyne trans-addition chemistry likely involves σ-complexes as reactive intermediates. Finally, it is discussed that interligand cooperativity might constitute a more general principle that extends to mechanistically distinct transformations. The presented data therefore make an interesting case for organometallic chemistry that provides inherently better results when applied to substrates containing unprotected rather than protected -OH, -NHR, or -COOH groups.
Susumu Isoda - One of the best experts on this subject based on the ideXlab platform.
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glycosides of atractylodes ovata
Chemical & Pharmaceutical Bulletin, 2003Co-Authors: Junichi Kitajima, Akane Kamoshita, Akihito Takano, Tatsuo Fukuda, Toru Ishikawa, Susumu IsodaAbstract:A new coumarin glycoside and a new glycoside of an Acetylene Derivative were isolated from the water-soluble portion of the methanolic extract of Atractylodes ovata rhizome together with eight known compounds. Their structures were characterized as scopoletin β-D-xylopyranosyl-(1→6)-β-D-glucopyranoside and (2E)-2-decene-4,6-diyne-1,8-diol 8-O-β-D-apiofuranosyl-(1→6)-β-D-glucopyranoside, respectively, based on chemical and spectroscopic investigations. A comparison of the polar constituents among Atractylodes japonica, Atractylodes lancea, and A. ovata is led to the conclusion that A. ovata is distinguishable from A. lancea and A. japonica, as also shown by phylogenetic analysis.
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glycosides of atractylodes ovata
Chemical & Pharmaceutical Bulletin, 2003Co-Authors: Junichi Kitajima, Akane Kamoshita, Akihito Takano, Tatsuo Fukuda, Toru Ishikawa, Susumu IsodaAbstract:A new coumarin glycoside and a new glycoside of an Acetylene Derivative were isolated from the water-soluble portion of the methanolic extract of Atractylodes ovata rhizome together with eight known compounds. Their structures were characterized as scopoletin β-D-xylopyranosyl-(1→6)-β-D-glucopyranoside and (2E)-2-decene-4,6-diyne-1,8-diol 8-O-β-D-apiofuranosyl-(1→6)-β-D-glucopyranoside, respectively, based on chemical and spectroscopic investigations. A comparison of the polar constituents among Atractylodes japonica, Atractylodes lancea, and A. ovata is led to the conclusion that A. ovata is distinguishable from A. lancea and A. japonica, as also shown by phylogenetic analysis.
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glycosides of atractylodes lancea
Chemical & Pharmaceutical Bulletin, 2003Co-Authors: Junichi Kitajima, Akane Kamoshita, Akihito Takano, Tatsuo Fukuda, Toru Ishikawa, Susumu IsodaAbstract:: Five sesquiterpenoid glycosides (two guaiane-type glycosides and three eudesmane-type glucosides) and a glucoside of an Acetylene Derivative were newly isolated from the water-soluble portion of the methanolic extract of Atractylodes lancea rhizome together with 26 known compounds. Their structures were characterized as atractyloside A 14-O-beta-D-fructofuranoside, (1S,4S,5S,7R,10S)-10,11,14-trihydroxyguai-3-one 11-O-beta-D-glucopyranoside, (5R,7R,10S)-isopterocarpolone beta-D-glucopyranoside, cis-atractyloside I, (2R,3R,5R,7R,10S)-atractyloside G 2-O-beta-D-glucopyranoside, and (2E,8E)-2,8-decadiene-4,6-diyne-1,10-diol 1-O-beta-D-glucopyranoside on the basis of chemical and spectroscopic investigation. The presence of six characteristic guaiane-type glucosides in both rhizomes of A. lancea and Atractylodes japonica suggested a close chemotaxonomic relationship between them.
