- Asymmetric Hydrogenation of Racemic Allylic Alcohols via an Isomerization-Dynamic Kinetic Resolution Cascade
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Prochiral racemic allylic alcohols are converted to enantioenriched chiral alcohols bearing adjacent stereocenters catalyzed by a diamine diphosphine Ru complex in the presence of tBuOK. The protocol features a broad substrate scope (56 examples) and high
- Guo, Xin,Niu, Saisai,Sun, Huaming,Tang, Weijun,Wang, Chao,Wang, Kun,Xiao, Jianliang,Xue, Dong
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- Asymmetric Transfer Hydrogenation of Arylidene-Substituted Chromanones and Tetralones Catalyzed by Noyori-Ikariya Ru(II) Complexes: One-Pot Reduction of C═C and C═O bonds
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3-Arylidenechroman-4-ones and 2-arylidene-1-tetralones are hydrogenated to cis-benzylic alcohols in dr's and er's up to 99:1 via a C═C and C═O one-pot reduction in the presence of 2-5 mol % Noyori-Ikariya-type RuII chiral complexes and HCO2Na as a hydroge
- Caleffi, Guilherme S.,Brum, Juliana De O. C.,Costa, Angela T.,Domingos, Jorge L. O.,Costa, Paulo R. R.
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p. 4849 - 4858
(2021/04/06)
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- Switchable β-alkylation of secondary alcohols with primary alcohols by a well-defined cobalt catalyst
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β-alkylation of secondary alcohols with primary alcohols to selectively generate alcohols by a well-defined Co catalyst is presented. Remarkably, a low catalyst loading of 0.7 mol % can be employed for the reaction. More significantly, this study represents the first Co-catalyzed switchable alcohol/ketone synthesis by simply manipulating the reaction parameters. In addition, the transformation is environmentally friendly, with water as the only byproduct.
- Ding, Keying,Pandey, Bedraj,Xu, Shi
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supporting information
p. 1207 - 1212
(2021/05/29)
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- Chelate ring size effects of Ir(P,N,N) complexes: Chemoselectivity switch in the asymmetric hydrogenation of α,β-unsaturated ketones
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A novel, highly modular approach has been developed for the synthesis of new chiral P,N,N ligands with the general formula Ph2P(CH3)CH(CH2)mCH(CH3)NHCH2CH2(CH2)nN(CH3)2 and Ph2P(CH3)CHCH2CH(CH3)NHCH2(CH2)n-2-Py (m, n = 0, 1). The systematic variation of their P–N and N–N backbone led to the conclusion that the activity, chemo- and enantioselectivity in the hydrogenation of α,β-unsaturated ketones are highly dependent on the combination of the two bridge lengths. It has been found that a minor change in the ligand's structure, i. e. varying the value of m from 1 to 0, can switch the chemoselectivity of the reaction, from 80percent C[dbnd]O to 97percent C[dbnd]C selectivity.
- Bényei, Attila C.,Bakos, József,Császár, Zsófia,Farkas, Gergely,Szabó, Eszter Z.
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- Iridium(I)-Catalyzed C-C and C-N Bond Formation Reactions via the Borrowing Hydrogen Strategy
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Iridium(I) complexes having an imidazol-2-ylidene ligand with benzylic wingtips efficiently catalyzed the β-alkylation of secondary alcohols with primary alcohols and acceptorless dehydrogenative cyclization of 2-aminobenzyl alcohol with ketones through a borrowing hydrogen pathway. The β-alkylated alcohols, including cholesterol derivatives, and substituted quinolines were obtained in good yields by using a minute amount of the catalyst with a catalytic amount of NaOH or KOH under the air atmosphere, liberating water (and H2 in the case of quinoline synthesis) as the sole byproduct. Notably, this system demonstrated turnover numbers of 940 000 (for β-alkylation of secondary alcohols with primary alcohols by using down to 0.0001 mol % = 1 ppm of the catalyst) and 9200 (acceptorless dehydrogenative cyclization of 2-aminobenzyl alcohol with ketones).
- Gen?, Serta?,Arslan, Burcu,Gülcemal, Süleyman,Günnaz, Salih,?etinkaya, Bekir,Gülcemal, Derya
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p. 6286 - 6297
(2019/05/17)
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- Isomerization-Asymmetric Hydrogenation Sequence Converting Racemic β-Ylidenecycloalkanols into Stereocontrolled β-Substituted Cycloalkanols Using a Ru Catalytic System with Dual Roles
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Racemic β-ylidenecycloalkanols were transformed into the cis-β-substituted cycloalkanols with high enantio- and diastereoselectivities through an isomerization-asymmetric hydrogenation sequence with the (4,4′-bi-1,3-benzodioxole)-5,5′-diylbis[di(3,5-xylyl)phosphine (DM-Segphos)/2-dimethylamino-1-phenylethylamine (DMAPEN)-ruthenium(II) catalyst; such transformation hardly proceeded by single-step asymmetric hydrogenation. The reaction was usually carried out with a substrate-to-catalyst molar ratio of 500 under 4 to 10 atm of H2 to afford the products in cis/trans ratio up to 99:1 and 98% ee. Mechanistic experiments suggested that this catalytic system reversibly formed two reactive species, types (I) and (II), through a ruthenacyclic amide intermediate. The amide complex and allylic alcohol reacted to afford the allylic alkoxide complex with partial or full removal of diamine (type (I)), and this type (I) complex catalyzed isomerization of the allylic alcohols into the racemic α-substituted ketones. The RuH2 complex with chelation of diamine (type (II)) formed by reaction of the amide complex and hydrogen promoted asymmetric hydrogenation of racemic α-substituted ketone into the stereocontrolled β-substituted cycloalkanols through dynamic kinetic resolution. (Figure presented.).
- Arai, Noriyoshi,Okabe, Yuki,Ohkuma, Takeshi
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p. 5540 - 5547
(2019/11/16)
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- Tandem Cross Coupling Reaction of Alcohols for Sustainable Synthesis of β-Alkylated Secondary Alcohols and Flavan Derivatives
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A Ru(II) NHC complex (loading down to 0.001 mol%) catalyzed cross coupling of a broad range of aromatic, aliphatic and heterocyclic alcohols is reported. This protocol also functioned efficiently under solvent-free conditions. Remarkably, this catalytic system disclosed so far the highest TON of 288000 for the cross coupling of alcohols. Notably, this methodology was successfully applied for the one-pot synthesis of a range of flavan derivatives. A detailed DFT studies and kinetic experiments were performed to understand the reaction mechanism as well as the high reactivity of this catalytic system. (Figure presented.).
- Shee, Sujan,Paul, Bhaskar,Panja, Dibyajyoti,Roy, Bivas Chandra,Chakrabarti, Kaushik,Ganguli, Kasturi,Das, Ayan,Das, Gourab Kanti,Kundu, Sabuj
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supporting information
p. 3888 - 3893
(2017/10/07)
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- The method of manufacturing the same
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PROBLEM TO BE SOLVED: To provide a method for producing a dimer which can obtain the dimer even in the absence of a specific transition metal such as Ir. SOLUTION: The method for producing a dimer comprises dimerizing an alcohol (1) (wherein R1and R2are each hydrogen or a monovalent hydrocarbon group) and an alcohol (2) (wherein R3and R4are each hydrogen or a monovalent hydrocarbon group) or a carbonyl compound (3) (wherein R3and R4are the same as defined above) in the presence of an alkali metal or an alkali metal base and in the absence of a transition metal. COPYRIGHT: (C)2011,JPOandINPIT
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Paragraph 0061-0065
(2017/02/02)
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- Bifunctional Ru(II) complex catalysed carbon-carbon bond formation: an eco-friendly hydrogen borrowing strategy
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The atom economical borrowing hydrogen methodology enables the use of alcohols as alkylating agents for selective C-C bond formation. A bifunctional 2-(2-pyridyl-2-ol)-1,10-phenanthroline (phenpy-OH) based Ru(ii) complex (2) was found to be a highly efficient catalyst for the one-pot β-alkylation of secondary alcohols with primary alcohols and double alkylation of cyclopentanol with different primary alcohols. Exploiting the metal-ligand cooperativity in complex 2, several aromatic, aliphatic and heteroatom substituted alcohols were selectively cross-coupled in high yields using significantly low catalyst loading (0.1 mol%). An outer-sphere mechanism is proposed for this system as exogenous PPh3 has no significant effect on the rate of the reaction. Notably, this is a rare one-pot strategy for β-alkylation of secondary alcohols using a bifunctional Ru(ii)-complex. Moreover, this atom-economical methodology displayed the highest cumulative turn over frequency (TOF) among all the reported transition metal complexes in cross coupling of alcohols.
- Chakrabarti, Kaushik,Paul, Bhaskar,Maji, Milan,Roy, Bivas Chandra,Shee, Sujan,Kundu, Sabuj
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p. 10988 - 10997
(2016/12/06)
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- Bifunctional RuII-Complex-Catalysed Tandem C?C Bond Formation: Efficient and Atom Economical Strategy for the Utilisation of Alcohols as Alkylating Agents
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Catalytic activities of a series of functional bipyridine-based RuIIcomplexes in β-alkylation of secondary alcohols using primary alcohols were investigated. Bifunctional RuIIcomplex (3 a) bearing 6,6’-dihydroxy-2,2’-bipyridine (6DHBP) ligand exhibited the highest catalytic activity for this reaction. Using significantly lower catalyst loading (0.1 mol %) dehydrogenative carbon?carbon bond formation between numerous aromatic, aliphatic and heteroatom substituted alcohols were achieved with high selectivity. Notably, for the synthesis of β-alkylated secondary alcohols this protocol is a rare one-pot strategy using a metal–ligand cooperative RuIIsystem. Remarkably, complex 3 a demonstrated the highest reactivity compared to all the reported transition metal complexes in this reaction.
- Roy, Bivas Chandra,Chakrabarti, Kaushik,Shee, Sujan,Paul, Subhadeep,Kundu, Sabuj
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supporting information
p. 18147 - 18155
(2016/12/16)
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- Catalyst-free dehydrative α-alkylation of ketones with alcohols: Green and selective autocatalyzed synthesis of alcohols and ketones
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Direct dehydrative α-alkylation reactions of ketones with alcohols are now realized under simple, practical, and green conditions without using external catalysts. These catalyst-free autocatalyzed alkylation methods can efficiently afford useful alkylated ketone or alcohol products in a one-pot manner and on a large scale by Ci£C bond formation of the in situ generated intermediates with subsequent controllable and selective Meerwein-Pondorf-Verley-Oppenauer-type redox processes. Plain and simple: The title reaction has been realized under simple and practical conditions without using external catalysts, and can afford alkylated ketone or alcohol products in a one-pot manner and on a large scale. The reaction proceeds by Ci£C bond formation of the in situ generated intermediates with subsequent controllable and selective Meerwein-Pondorf-Verley-Oppenauer-type redox processes. Copyright
- Xu, Qing,Chen, Jianhui,Tian, Haiwen,Yuan, Xueqin,Li, Shuangyan,Zhou, Chongkuan,Liu, Jianping
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p. 225 - 229
(2014/01/17)
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- Aldehyde-catalyzed transition metal-free dehydrative β-alkylation of methyl carbinols with alcohols
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Different to the borrowing hydrogen strategy in which alcohols were activated by transition metal-catalyzed anaerobic dehydrogenation, the direct addition of aldehydes was found to be an effective but simpler way of alcohol activation that can lead to efficient and green aldehyde-catalyzed transition metal-free dehydrative C-alkylation of methyl carbinols with alcohols. Mechanistic studies revealed that the reaction proceeds via in situ formation of ketones by Oppenauer oxidation of the methyl carbinols by external aldehydes, aldol condensation, and Meerwein-Ponndorf-Verley (MPV)-type reduction of α,β-unsatutated ketones by substrate alcohols, affording the useful long chain alcohols and generating aldehydes and ketones as the by-products that will be recovered in the next condensation to finish the catalytic cycle. Copyright
- Xu, Qing,Chen, Jianhui,Liu, Quan
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p. 697 - 704
(2013/04/10)
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- Tris(acetylacetonato)rhodium(III)-catalyzed α-alkylation of ketones, β-alkylation of secondary alcohols and alkylation of amines with primary alcohols
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The tris(acetylacetonato)rhodium(III) catalyst is shown to be a versatile catalyst in the presence of DABCO (1,4-diazabicyclo[2.2.2]octane) as ligand for the α-alkylation of ketones followed by transfer hydrogenation, for the one-pot β-alkylation of secondary alcohols with primary alcohols and for the alkylation of aromatic amines in the presence of an inorganic base in toluene. Copyright
- Satyanarayana, Ponnam,Reddy, Ganapam Manohar,Maheswaran, Hariharasharma,Kantam, Mannepalli Lakshmi
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supporting information
p. 1859 - 1867
(2013/07/19)
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- Structural studies of seven homoisoflavonoids, six thiohomoisoflavonoids, and four structurally related compounds
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1H and 13C NMR chemical shifts have been determined and assigned based on PFG 1H, 13C HM...C, and HMBC experiments for 3-(4'-X-benzyl)-4-chromenones (Ia, X = CN and Ib, X = NO 2), 3-(4'-X-benzyl)-4-th
- Valkonen, Arto,Laihia, Katri,Kolehmainen, Erkki,Kauppinen, Reijo,Perjesi, Pal
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experimental part
p. 209 - 217
(2012/09/07)
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- Carbon-carbon bond formation between secondary alcohols and aldehydes under ruthenium-catalyzed redox shuttle
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Secondary alcohols are coupled with aldehydes in dioxane in the presence of a catalytic amount of a ruthenium catalyst along with KOH to give coupled ketones or coupled secondary alcohols depending on the molar ratio of secondary alcohols to aldehydes and the presence (or absence) of a sacrificial hydrogen acceptor. Copyright
- Cho, Chan Sik,Kim, Bok Tae,Yoon, Nam Sik
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experimental part
p. 695 - 698
(2012/01/05)
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- Cross-coupling reaction of alcohols for carbon-carbon bond formation using pincer-type NHC/palladium catalysts
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A cross-coupling reaction of different alcohols was achieved using a pincer-type NHC/PdBr complex as the catalyst precursor, and the reaction, under either Ar or H2 gas, displayed a broad substrate scope with respect to both primary and secondary alcohol components, with high alcohol product selectivity. The Royal Society of Chemistry 2010.
- Kose, Osamu,Saito, Susumu
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scheme or table
p. 896 - 900
(2010/06/20)
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- Palladium on charcoal plus enantiopure amino alcohols as catalytic systems for the enantioselective 1,4-reduction of α-substituted α,β-unsaturated ketones
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The chemoselective reduction of α, β-unsaturated cyclic ketones 1-7 to the corresponding saturated ketones 8-12 was shown to proceed mainly by 1,4-addition of hydrogen to the activated double bond, resulting in enolic species. These entities could be selectively protonated in the presence of enantiopure amino alcohols to afford the corresponding saturated ketones with ee values of up to 47%. Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002.
- Thorey, Claire,Bouquillon, Sandrine,Helimi, Abdellatif,Henin, Francoise,Muzart, Jacques
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p. 2151 - 2159
(2007/10/03)
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- Highly stereoselective synthesis of 1,3-aminoalcohols via Mannich reactions
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Diastereoselective synthesis of β-amino ketones by a one-pot Mannich reaction and their subsequent reduction afforded sterically congested enantiomerically pure 1,3-aminoalcohols in high diastereoselectivity: dr up to >98:2 over two steps. The absolute configurations of the newly created stereogenic centers were assigned by NMR spectroscopy and chemical correlation.
- Kossenjans, Michael,Martens, Juergen
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p. 3409 - 3416
(2007/10/03)
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- Hydroxy-Directed Hydroaluminations: A Stereoselective Approach to Cycloalkanols From β-Aryl Enones.
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Various aryl substituted enones are reduced using lithium aluminum hydride to afford sterioselectively trans substituted alkanols.Mechanistic studies demonstrate 1,2-addition followed by hydroxy-directed hydroalumination of the conjugated styryl unit.
- Koch, Kevin,Smitrovich, Jacqueline H.
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p. 1137 - 1140
(2007/10/02)
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- The photochemical rearrangement of 1,2-dihydronaphthalenes into 1,4-dihydronaphthalenes induced by amines
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The synthetic usefulness of the deprotonation/protonation reaction of excited 1,2-dihydronaphthalenes into 1,4-dihydronaphthalenes induced by amines has been investigated using 13 different substituted 1,2-dihydronaphthalenes and related compounds.The yield of the rearrangement ranges from 5 to 96percent.The formation of side-products depends on the position of protons in the substrate, which can be abstracted by the amine, and on competitive photoreactions.
- Cuppen, Th. J. H. M.,Berendsen, N.,Laarhoven, W. H.
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p. 168 - 171
(2007/10/02)
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