The Experts below are selected from a list of 3690 Experts worldwide ranked by ideXlab platform
Tsutomu Katsuki - One of the best experts on this subject based on the ideXlab platform.
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Iron‐Catalyzed Asymmetric Tandem Spiro‐Cyclization Using Dioxygen in Air as the Hydrogen Acceptor.
ChemInform, 2014Co-Authors: Takuya Oguma, Tsutomu KatsukiAbstract:An efficient approach for the enantioselective formation of spirocyclic dihydrobenzofurans (III) from 1-methyl-2-naphthols (I) and phenol derivatives (II) via a new Fe-salan complex catalyzed [aerobic oxidative ortho-quinone methide formation followed by Michael addition and asymmetric dearomatization] is developed.
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iron catalysed asymmetric tandem spiro cyclization using dioxygen in air as the Hydrogen Acceptor
Chemical Communications, 2014Co-Authors: Tsutomu Katsuki, Takuya OgumaAbstract:A tandem combination of ortho-quinone methide (o-QM) formation/Michael addition/asymmetric dearomatization, which is catalysed by an iron–salan complex in air with high enantioselectivity, provides an efficient method for spirocyclic (2H)-dihydrobenzofuran synthesis from 2-naphthols and phenols. The key to the success of the tandem synthesis is the development of aerobic oxidative o-QM formation.
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ruthenium catalyzed oxidative kinetic resolution of unactivated and activated secondary alcohols with air as the Hydrogen Acceptor at room temperature
Angewandte Chemie, 2014Co-Authors: Hirotaka Mizoguchi, Tatsuya Uchida, Tsutomu KatsukiAbstract:Enantiopure alcohols are versatile building blocks for asymmetric synthesis and the kinetic resolution (KR) of racemic alcohols is a reliable method for preparing them. Although many KR methods have been developed, oxidative kinetic resolution (OKR), in which dioxygen is used as the Hydrogen Acceptor, is the most atom-efficient. Dioxygen is ubiquitous in air, which is abundant and safe to handle. Therefore, OKR with air has been intensively investigated and the OKR of benzylic alcohols was recently achieved by using an Ir catalyst without any adjuvant. However, the OKR of unactivated alcohols remains a challenge. An [(aqua)Ru(salen)] catalyzed OKR with air as the Hydrogen Acceptor was developed, in which the aqua ligand is exchanged with alcohol and the Ru complex undergoes single electron transfer to dioxygen and subsequent alcohol oxidation. This OKR can be applied without any adjuvant to activated and unactivated alcohols with good to high enantioselectivity. The unique influence of substrate inhibition on the enantioselectivity of the OKR is also described.
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Ruthenium‐Catalyzed Oxidative Kinetic Resolution of Unactivated and Activated Secondary Alcohols with Air as the Hydrogen Acceptor at Room Temperature
Angewandte Chemie (International ed. in English), 2014Co-Authors: Hirotaka Mizoguchi, Tatsuya Uchida, Tsutomu KatsukiAbstract:Enantiopure alcohols are versatile building blocks for asymmetric synthesis and the kinetic resolution (KR) of racemic alcohols is a reliable method for preparing them. Although many KR methods have been developed, oxidative kinetic resolution (OKR), in which dioxygen is used as the Hydrogen Acceptor, is the most atom-efficient. Dioxygen is ubiquitous in air, which is abundant and safe to handle. Therefore, OKR with air has been intensively investigated and the OKR of benzylic alcohols was recently achieved by using an Ir catalyst without any adjuvant. However, the OKR of unactivated alcohols remains a challenge. An [(aqua)Ru(salen)] catalyzed OKR with air as the Hydrogen Acceptor was developed, in which the aqua ligand is exchanged with alcohol and the Ru complex undergoes single electron transfer to dioxygen and subsequent alcohol oxidation. This OKR can be applied without any adjuvant to activated and unactivated alcohols with good to high enantioselectivity. The unique influence of substrate inhibition on the enantioselectivity of the OKR is also described.
Sang Chul Shim - One of the best experts on this subject based on the ideXlab platform.
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ruthenium catalyzed oxidative coupling and cyclization between 2 aminobenzyl alcohol and secondary alcohols leading to quinolines
Tetrahedron, 2003Co-Authors: Heungjin Choi, Sang Chul ShimAbstract:Abstract 2-Aminobenzyl alcohol is oxidatively coupled and cyclized with secondary alcohols in dioxane at 80°C in the presence of a catalytic amount of RuCl 2 (PPh 3 ) 3 and KOH along with 1-dodecene as a sacrificial Hydrogen Acceptor to give the corresponding quinolines in good yields. The cyclization is applicable to a wide range of alkyl(aryl) and alkyl(alkyl) carbinols. The catalytic pathway seems to be proceeded via a sequence involving initial oxidation of both substrates to carbonyl compounds, cross aldol reaction, and cyclodehydration.
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Ruthenium-catalyzed one-pot β-alkylation of Secondary alcohols with primary alcohols
Organometallics, 2003Co-Authors: Sang Chul ShimAbstract:Secondary alcohols (carbinols) react with primary alcohols in dioxane at 80 °C in the presence of a catalytic amount of RuCl2(PPh3)3 and KOH along with a sacrificial Hydrogen Acceptor to afford the corresponding coupled secondary alcohols. The reaction is applicable to a wide range of aryl methyl, alkyl methyl, and cyclic carbinols, and with alkyl methyl carbinols, the alkylation took place exclusively at the less-hindered methyl position over β-methylene and -methine.
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Ruthenium-Catalyzed Synthesis of Quinolines from Anilines and Tris(3-hydroxypropyl)amine via Amine Exchange Reaction
Bulletin of the Korean Chemical Society, 2003Co-Authors: Chan Sik Cho, Dong Tak Kim, Tae-jeong Kim, Sang Chul ShimAbstract:O, 3a was produced in only 5% yield (entry 2).Furthermore, the addition of a suitable Hydrogen Acceptorwas necessary for the effective formation of 3a. Performingthe reaction in the absence of Hydrogen Acceptor resulted in alower yield of 3a when compared to the reaction in thepresence of Hydrogen Acceptor (entries 1 and 3). SeveralHydrogen Acceptors such as acetophenone and dodec-1-enecould be alternatively used, but the yield of 3a was lowerthan that when acetone was used (entries 4 and 5). However,performing the reaction in the presence of oct-1-yne wasineffective and GLC analysis of crude reaction mixtureshowed very complicated products, which may be attributedto dimerization and trimerization of oct-1-yne under rutheniumcatalyst system (entry 6).
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Ruthenium-catalyzed regioselective α-alkylation of ketones with primary alcohols
Tetrahedron Letters, 2002Co-Authors: Chan Sik Cho, Tae-jeong Kim, Bok Tae Kim, Sang Chul ShimAbstract:Ketones are regioselectively alkylated with an array of primary alcohols in dioxane at 80°C in the presence of a catalytic amount of a ruthenium catalyst together with KOH and a Hydrogen Acceptor.
Masahiko Hayashi - One of the best experts on this subject based on the ideXlab platform.
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DeHydrogenative Formation of Resorcinol Derivatives Using Pd/C–Ethylene Catalytic System
Journal of Organic Chemistry, 2017Co-Authors: Ibrahim Yussif El-deeb, Tatsuya Funakoshi, Ryosuke Matsubara, Yuya Shimomoto, Masahiko HayashiAbstract:The conversion of substituted 1,3-cyclohexanediones to the alkyl ethers of resorcinol using a Pd/C–ethylene system is reported. In these reactions, ethylene works as a Hydrogen Acceptor. The efficient synthesis of resveratrol was achieved using this protocol as a key step. In addition, the direct formation of substituted resorcinols was carried out by adding K2CO3 into the reaction media.
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Conversion of Cyclohexanones to Alkyl Aryl Ethers by Using a Pd/C–Ethylene System
European Journal of Organic Chemistry, 2017Co-Authors: Ibrahim Yussif El-deeb, Miaomiao Tian, Tatsuya Funakoshi, Ryosuke Matsubara, Masahiko HayashiAbstract:The conversion of cyclohexanone and substituted cyclohexanones to alkyl aryl ethers using a Pd/C-ethylene system is discussed, where ethylene functions as a Hydrogen Acceptor. The obtained ethers are easily transformed into the corresponding phenols by treatment with BBr3. Direct conversion of cyclohexenone to phenol in the presence of a catalytic amount of Pd/C under an ethylene atmosphere is also described.
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Nitrobenzene as Hydrogen Acceptor in Pd/C-catalyzed Hydrogen transfer reaction
Tetrahedron Letters, 2005Co-Authors: Takanori Tanaka, Hirotoshi Kawabata, Masahiko HayashiAbstract:Nitrobenzene was found to work as an efficient Hydrogen Acceptor in the oxidation of allylic alcohols to give the corresponding enones in high yields.
Takuya Oguma - One of the best experts on this subject based on the ideXlab platform.
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Iron‐Catalyzed Asymmetric Tandem Spiro‐Cyclization Using Dioxygen in Air as the Hydrogen Acceptor.
ChemInform, 2014Co-Authors: Takuya Oguma, Tsutomu KatsukiAbstract:An efficient approach for the enantioselective formation of spirocyclic dihydrobenzofurans (III) from 1-methyl-2-naphthols (I) and phenol derivatives (II) via a new Fe-salan complex catalyzed [aerobic oxidative ortho-quinone methide formation followed by Michael addition and asymmetric dearomatization] is developed.
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iron catalysed asymmetric tandem spiro cyclization using dioxygen in air as the Hydrogen Acceptor
Chemical Communications, 2014Co-Authors: Tsutomu Katsuki, Takuya OgumaAbstract:A tandem combination of ortho-quinone methide (o-QM) formation/Michael addition/asymmetric dearomatization, which is catalysed by an iron–salan complex in air with high enantioselectivity, provides an efficient method for spirocyclic (2H)-dihydrobenzofuran synthesis from 2-naphthols and phenols. The key to the success of the tandem synthesis is the development of aerobic oxidative o-QM formation.
Jonathan M. J. Williams - One of the best experts on this subject based on the ideXlab platform.
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Ruthenium-catalysed oxidation of alcohols to amides using a Hydrogen Acceptor
Tetrahedron, 2014Co-Authors: Andrew J. A. Watson, Russell J. Wakeham, Aoife C. Maxwell, Jonathan M. J. WilliamsAbstract:Abstract A wider investigation into the synthesis of secondary amides from primary alcohols using a Hydrogen Acceptor using commercially available [Ru( p -cymene)Cl 2 ] 2 with bis(diphenylphosphino)butane (dppb) as the catalyst. The report looks at over 50 examples with varying functionality and steric bulk, whilst also covering the first reported results using microwave heating to effect the transformation.
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oxidation of primary alcohols to methyl esters by Hydrogen transfer
Chemical Communications, 2008Co-Authors: Nathan A Owston, Alexandra J Parker, Jonathan M. J. WilliamsAbstract:The oxidation of alcohols in the presence of methanol has been achieved using a ruthenium catalyst with crotononitrile as the Hydrogen Acceptor.
