The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Masataka Ihara - One of the best experts on this subject based on the ideXlab platform.
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palladium catalyzed ring expansion reaction of z 1 1 3 butadienyl cyclobutanols with aryl iodides stereospecific synthesis of z 2 3 aryl 1 propenyl Cyclopentanones
Organic Letters, 2004Co-Authors: Masahiro Yoshida, Kenji Sugimoto, Masataka IharaAbstract:[reaction: see text] A novel type of cascade ring expansion process has been developed by the palladium-catalyzed reaction of (Z)-1-(1,3-butadienyl)cyclobutanols with aryl iodides. The reaction proceeds in a stereospecific manner to produce (Z)-2-(3-aryl-1-propenyl)Cyclopentanones. It has also been found that regioselective alpha-arylation of alkenyl Cyclopentanones proceeds to afford the alpha-arylated Cyclopentanones.
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palladium catalyzed stereospecific ring expansion reaction of allenylcyclobutanols with aryl iodides a novel route to the α substituted Cyclopentanones with quaternary carbon stereocenters
Tetrahedron Letters, 2000Co-Authors: Masahiro Yoshida, Kenji Sugimoto, Masataka IharaAbstract:Abstract Stereoselective synthesis of α-substituted Cyclopentanones with quaternary carbon stereocenters has been achieved by the palladium-catalyzed rearrangement of allenylcyclobutanols with aryl iodides.
Guangbin Dong - One of the best experts on this subject based on the ideXlab platform.
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distal bond selective c c activation of ring fused Cyclopentanones an efficient access to spiroindanones
Angewandte Chemie, 2017Co-Authors: Guangbin Dong, Ying Xia, Jianbo WangAbstract:A site-selective rhodium-catalyzed C-C activation of ring-fused Cyclopentanones was achieved to afford efficient access to a range of spiroindanones. The use of bulky 2-amino-6-picoline as a cocatalyst is key to the excellent selectivity of this C-C bond cleavage in Cyclopentanones.
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catalytic activation of carbon carbon bonds in Cyclopentanones
Nature, 2016Co-Authors: Ying Xia, Guangbin Dong, Peng LiuAbstract:In the chemical industry, molecules of interest are based primarily on carbon skeletons. When synthesizing such molecules, the activation of carbon-carbon single bonds (C-C bonds) in simple substrates is strategically important: it offers a way of disconnecting such inert bonds, forming more active linkages (for example, between carbon and a transition metal) and eventually producing more versatile scaffolds. The challenge in achieving such activation is the kinetic inertness of C-C bonds and the relative weakness of newly formed carbon-metal bonds. The most common tactic starts with a three- or four-membered carbon-ring system, in which strain release provides a crucial thermodynamic driving force. However, broadly useful methods that are based on catalytic activation of unstrained C-C bonds have proven elusive, because the cleavage process is much less energetically favourable. Here we report a general approach to the catalytic activation of C-C bonds in simple Cyclopentanones and some cyclohexanones. The key to our success is the combination of a rhodium pre-catalyst, an N-heterocyclic carbene ligand and an amino-pyridine co-catalyst. When an aryl group is present in the C3 position of cyclopentanone, the less strained C-C bond can be activated; this is followed by activation of a carbon-hydrogen bond in the aryl group, leading to efficient synthesis of functionalized α-tetralones-a common structural motif and versatile building block in organic synthesis. Furthermore, this method can substantially enhance the efficiency of the enantioselective synthesis of some natural products of terpenoids. Density functional theory calculations reveal a mechanism involving an intriguing rhodium-bridged bicyclic intermediate.
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practical direct α arylation of Cyclopentanones by palladium enamine cooperative catalysis
Angewandte Chemie, 2016Co-Authors: Zhongxing Huang, Guangbin DongAbstract:Direct arylation of Cyclopentanones has been a long-standing challenge because of competitive self-aldol condensation and multiple arylations. Reported herein is a direct mono-α-C−H arylation of Cyclopentanones with aryl bromides which is enabled by palladium/amine cooperative catalysis. This method is scalable and chemoselective with broad functional-group tolerance. Application to controlled sequential arylation of Cyclopentanones has been also demonstrated.
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tetramethyl thiourea co 2 co 8 catalyzed pauson khand reaction under balloon pressure of co
Organic Letters, 2005Co-Authors: Yefeng Tang, Guangbin Dong, Lujiang Deng, Yandong Zhang, Jiahua Chen, Zhen YangAbstract:A Pauson−Khand type of conversion of enynes to bicyclic cyclopentenones employing the commercially available Co2(CO)8 and tetramethylthiourea (TMTU) as catalysts is described. This method allows a variety of enynes with diverse functional groups to be cyclized into cyclopentenones of interest.
Masahiro Yoshida - One of the best experts on this subject based on the ideXlab platform.
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palladium catalyzed ring expansion reaction of z 1 1 3 butadienyl cyclobutanols with aryl iodides stereospecific synthesis of z 2 3 aryl 1 propenyl Cyclopentanones
Organic Letters, 2004Co-Authors: Masahiro Yoshida, Kenji Sugimoto, Masataka IharaAbstract:[reaction: see text] A novel type of cascade ring expansion process has been developed by the palladium-catalyzed reaction of (Z)-1-(1,3-butadienyl)cyclobutanols with aryl iodides. The reaction proceeds in a stereospecific manner to produce (Z)-2-(3-aryl-1-propenyl)Cyclopentanones. It has also been found that regioselective alpha-arylation of alkenyl Cyclopentanones proceeds to afford the alpha-arylated Cyclopentanones.
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palladium catalyzed stereospecific ring expansion reaction of allenylcyclobutanols with aryl iodides a novel route to the α substituted Cyclopentanones with quaternary carbon stereocenters
Tetrahedron Letters, 2000Co-Authors: Masahiro Yoshida, Kenji Sugimoto, Masataka IharaAbstract:Abstract Stereoselective synthesis of α-substituted Cyclopentanones with quaternary carbon stereocenters has been achieved by the palladium-catalyzed rearrangement of allenylcyclobutanols with aryl iodides.
Jeanhilaire Saurat - One of the best experts on this subject based on the ideXlab platform.
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a toxicologic and dermatologic assessment of Cyclopentanones and cyclopentenones when used as fragrance ingredients
Food and Chemical Toxicology, 2012Co-Authors: D Belsito, David R Bickers, M Bruze, P Calow, M L Dagli, W Dekant, Allison Fryer, Helmut Greim, Yoshiki Miyachi, Jeanhilaire SauratAbstract:The cyclopentanone and cyclopentenone group of fragrance ingredients was critically evaluated for safety following a complete literature search. For high end users, calculated maximum dermal exposures vary from 0.002% to 15.16% in hydroalcoholic products; systemic exposures vary from 0.0003 to 0.7122 mg/kg/day. The Cyclopentanones and cyclopentenones had a low order of acute toxicity and no significant toxicity in repeat dose studies. No mutagenic or genotoxic activity in bacteria and mammalian cell line assays was observed. Developmental toxicity was not observed. Minimal evidence of skin irritation in humans is associated with current levels of use. Eleven materials were tested undiluted for eye irritation; three were considered irritants. No phototoxic and photosensitization reactions were seen with nine materials tested. At concentrations higher than current reported use, 14 materials were non-sensitizing in HRIPT or maximization tests. 2-Hexylidene cyclopentanone, 2-heptylidenecyclopentan-1-one and 3-methyl-2-(pentyloxy)-2-cyclopenten-1-one are weak sensitizers and have IFRA Standards. Risk of sensitization to the Cyclopentanones and cyclopentenones is generally small under current levels of use. The Panel is of the opinion that there are no safety concerns for the Cyclopentanones and cyclopentenones at reported levels of use and exposure as fragrance ingredients. (C) 2012 Elsevier Ltd. All rights reserved. (Less)
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a toxicologic and dermatologic assessment of Cyclopentanones and cyclopentenones when used as fragrance ingredients
Food and Chemical Toxicology, 2012Co-Authors: D Belsito, David R Bickers, M Bruze, P Calow, M L Dagli, W Dekant, Helmut Greim, Yoshiki Miyachi, A D Fryer, Jeanhilaire SauratAbstract:The cyclopentanone and cyclopentenone group of fragrance ingredients was critically evaluated for safety following a complete literature search. For high end users, calculated maximum dermal exposures vary from 0.002% to 15.16% in hydroalcoholic products; systemic exposures vary from 0.0003 to 0.7122 mg/kg/day. The Cyclopentanones and cyclopentenones had a low order of acute toxicity and no significant toxicity in repeat dose studies. No mutagenic or genotoxic activity in bacteria and mammalian cell line assays was observed. Developmental toxicity was not observed. Minimal evidence of skin irritation in humans is associated with current levels of use. Eleven materials were tested undiluted for eye irritation; three were considered irritants. No phototoxic and photosensitization reactions were seen with nine materials tested. At concentrations higher than current reported use, 14 materials were non-sensitizing in HRIPT or maximization tests. 2-Hexylidene cyclopentanone, 2-heptylidenecyclopentan-1-one and 3-methyl-2-(pentyloxy)-2-cyclopenten-1-one are weak sensitizers and have IFRA Standards. Risk of sensitization to the Cyclopentanones and cyclopentenones is generally small under current levels of use. The Panel is of the opinion that there are no safety concerns for the Cyclopentanones and cyclopentenones at reported levels of use and exposure as fragrance ingredients.
M L Dagli - One of the best experts on this subject based on the ideXlab platform.
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rifm fragrance ingredient safety assessment methyl hexyl oxo cyclopentanone carboxylate cas registry number 37172 53 5
Food and Chemical Toxicology, 2017Co-Authors: A M Api, M Bruze, P Calow, Donald V Belsito, S P Bhatia, D Botelho, D Browne, G A Burton, J Buschmann, M L DagliAbstract:• Methyl hexyl oxo cyclopentanone carboxylate safety assessment based on RIFM's criteria.
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a toxicologic and dermatologic assessment of Cyclopentanones and cyclopentenones when used as fragrance ingredients
Food and Chemical Toxicology, 2012Co-Authors: D Belsito, David R Bickers, M Bruze, P Calow, M L Dagli, W Dekant, Allison Fryer, Helmut Greim, Yoshiki Miyachi, Jeanhilaire SauratAbstract:The cyclopentanone and cyclopentenone group of fragrance ingredients was critically evaluated for safety following a complete literature search. For high end users, calculated maximum dermal exposures vary from 0.002% to 15.16% in hydroalcoholic products; systemic exposures vary from 0.0003 to 0.7122 mg/kg/day. The Cyclopentanones and cyclopentenones had a low order of acute toxicity and no significant toxicity in repeat dose studies. No mutagenic or genotoxic activity in bacteria and mammalian cell line assays was observed. Developmental toxicity was not observed. Minimal evidence of skin irritation in humans is associated with current levels of use. Eleven materials were tested undiluted for eye irritation; three were considered irritants. No phototoxic and photosensitization reactions were seen with nine materials tested. At concentrations higher than current reported use, 14 materials were non-sensitizing in HRIPT or maximization tests. 2-Hexylidene cyclopentanone, 2-heptylidenecyclopentan-1-one and 3-methyl-2-(pentyloxy)-2-cyclopenten-1-one are weak sensitizers and have IFRA Standards. Risk of sensitization to the Cyclopentanones and cyclopentenones is generally small under current levels of use. The Panel is of the opinion that there are no safety concerns for the Cyclopentanones and cyclopentenones at reported levels of use and exposure as fragrance ingredients. (C) 2012 Elsevier Ltd. All rights reserved. (Less)
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a toxicologic and dermatologic assessment of Cyclopentanones and cyclopentenones when used as fragrance ingredients
Food and Chemical Toxicology, 2012Co-Authors: D Belsito, David R Bickers, M Bruze, P Calow, M L Dagli, W Dekant, Helmut Greim, Yoshiki Miyachi, A D Fryer, Jeanhilaire SauratAbstract:The cyclopentanone and cyclopentenone group of fragrance ingredients was critically evaluated for safety following a complete literature search. For high end users, calculated maximum dermal exposures vary from 0.002% to 15.16% in hydroalcoholic products; systemic exposures vary from 0.0003 to 0.7122 mg/kg/day. The Cyclopentanones and cyclopentenones had a low order of acute toxicity and no significant toxicity in repeat dose studies. No mutagenic or genotoxic activity in bacteria and mammalian cell line assays was observed. Developmental toxicity was not observed. Minimal evidence of skin irritation in humans is associated with current levels of use. Eleven materials were tested undiluted for eye irritation; three were considered irritants. No phototoxic and photosensitization reactions were seen with nine materials tested. At concentrations higher than current reported use, 14 materials were non-sensitizing in HRIPT or maximization tests. 2-Hexylidene cyclopentanone, 2-heptylidenecyclopentan-1-one and 3-methyl-2-(pentyloxy)-2-cyclopenten-1-one are weak sensitizers and have IFRA Standards. Risk of sensitization to the Cyclopentanones and cyclopentenones is generally small under current levels of use. The Panel is of the opinion that there are no safety concerns for the Cyclopentanones and cyclopentenones at reported levels of use and exposure as fragrance ingredients.
