- Asymmetric synthesis of tertiary vinyl carbinols by highly stereoselective methylation of α-methyl-β-ketosulfoxides with aluminum reagents
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Methylation of chiral acyclic α-methyl-β-ketosulfoxides with Me3Al and Me2AlCl is reported. Induced configuration at hydroxylic carbon is mainly controlled by the configuration of the sulfinyl group, with de's higher than 90% in most of the cases regardless the configuration at C-α. The stereochemical pathway seems to be different with both reagents, thus affording a higher stereoselectivity with Me 2AlCl. Pyrolytic desulfinylation and hydrogenolysis of the C-S bond allowed the transformation of the resulting hydroxysulfoxides into interesting optically pure tertiary methyl carbinols.
- García Ruano, José L.,Rodríguez-Fernández, M. Mercedes,Maestro, M.Carmen
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Read Online
- Harnessing the Power of the Asymmetric Grignard Synthesis of Tertiary Alcohols: Ligand Development and Improved Scope Exemplified by One-Step Gossonorol Synthesis
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A series of N-substituted cyclohexyldiaminophenolic ligands for the asymmetric Grignard synthesis of tertiary alcohols is reported. The 2,5-dimethylpyrrole-decorated ligand led to improved enantioselectivities and broadened the scope of the methodology. As an exemplar, we report an unprecedented highly selective one-step synthesis of gossonorol in 93% ee, also constituting the shortest formal syntheses of natural products boivinianin B and yingzhaosu C.
- Gilheany, Declan G.,Kavanagh, Saranna E.
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supporting information
p. 8198 - 8203
(2020/11/18)
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- Very short highly enantioselective Grignard synthesis of 2,2-disubstituted tetrahydrofurans and tetrahydropyrans
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Phenones with elongated chains are shown to be excellent substrates for ligand-promoted asymmetric Grignard synthesis of tertiary alcohols. In turn this enables the simple, short and highly enantioselective (up to 96% ee) preparation of chiral 2,2-disubst
- Monasterolo, Claudio,Müller-Bunz, Helge,Gilheany, Declan G.
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p. 6531 - 6538
(2019/07/10)
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- Asymmetric Grignard Synthesis of Tertiary Alcohols through Rational Ligand Design
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A simple, general and practical method is reported for highly enantioselective construction of tertiary alcohols through the direct addition of organomagnesium reagents to ketones. Discovered by rational ligand design based on a mechanistic hypothesis, it has an unprecedented broad scope. It utilizes a new type of chiral tridentate diamine/phenol ligand that is easily removed from the reaction mixture. It is exemplified by application to a formal asymmetric synthesis (>95:5 d.r.) of vitamin E.
- Bieszczad, Bartosz,Gilheany, Declan G.
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supporting information
p. 4272 - 4276
(2017/04/03)
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- CHIRAL DIAMINE COMPOUNDS FOR THE PREPARATION OF CHIRAL ALCOHOL AND CHIRAL AMINE
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A process for the stereoselective preparation of a chiral alcohol or a chiral amine, the process comprising reacting a first prochiral reactant selected from the group consisting of a ketone, an aldehyde, and an inline, with a second reactant comprising a Grignard reagent, in the presence of a chiral trans-diamim of formula (1) as defined herein. Also provided is the use of the chiral trans-diamine of formula (1) in a Grignard reaction and the chiral trans-diamines per se.
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Page/Page column 64
(2015/12/17)
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- QSAR analysis of the catalytic asymmetric ethylation of ketone using physical steric parameters of chiral ligand substituents
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We have demonstrated that a validated QSAR (quantitative structure-activity relationship) model can be constructed between sterimol steric parameters of the N-substituents of chiral 1,2-amino-phosphoramide ligands and the enantiomeric ratios of alcohol products produced in the asymmetric additions of diethylzinc to acetophenone, which is powerful for predicting the steric effects of ligand substituents on enantioselectivities and instructive for ligand optimization.
- Huang, Huayin,Zong, Hua,Shen, Bin,Yue, Huifeng,Bian, Guangling,Song, Ling
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supporting information
p. 1289 - 1297
(2014/02/14)
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- Molecular and Merrifield supported chiral diamines for enantioselective addition of ZnR2 (R = Me, Et) to ketones
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Chiral 1,2-ethylenediamines have been previously reported as active catalysts in the enantioselective addition reactions of ZnR2 to either methyl- or trifluoromethyl-ketones. Subtle changes in the molecular structure of different catalysts are described herein and lead to a dramatic effect in their catalytic activity. From these findings, we demonstrate the selective reactivity of the ligands used in the addition of ZnR2 (R = Me, Et) to methyl- and trifluoromethyl-ketones offering an enantioselective access either to chiral non-fluorinated alcohols or to chiral fluorinated tertiary alcohols. Considering the importance of the chiral trifluoromethyl carbinol fragment in several biologically active compounds, we have extended the scope of the addition reaction of ZnEt2 to several trifluoromethylketones catalyzed by (R,R)-1,2-diphenylethylenediamine derivatives. This work explores a homogeneous approach that provides excellent yields and very high ee and the use of a heterogenized tail-tied ligand affording moderate ee, high yields and allowing an easier handling and recycling.
- Calvillo-Barahona, Mercedes,Cordovilla, Carlos,Genov, Miroslav N.,Martinez-Ilarduya, Jesus M.,Espinet, Pablo
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p. 14576 - 14582
(2013/10/08)
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- New ligands and structural insights into the catalytic asymmetric addition of organozinc reagents to ketones
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The catalytic asymmetric addition of alkyl groups to ketones has received considerable attention. Outlined herein is the synthesis of two new ligands based on the C2-symmetric 11,12-diamino-9,10-dihydro-9,10- ethanoanthracene. The scope of the new ligands has been evaluated in the catalytic asymmetric addition of diethylzinc to a variety of ketones. Enantioselectivities as high as 99% have been achieved. The structures of two of these ligands have been determined by X-ray crystallography and are compared with related structures. Additionally, the structure of a titanium complex bound to a bis(sulfonamide) diol ligand is reported.
- Huelgas, Gabriela,Larochelle, Lynne K.,Rivas, Lucrecia,Luchinina, Yekaterina,Toscano, Rubén A.,Carroll, Patrick J.,Walsh, Patrick J.,Anaya De Parrodi, Cecilia
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experimental part
p. 4467 - 4474
(2011/08/04)
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- Commercially available neat organozincs as highly reactive reagents for catalytic enantioselective addition to ketones and aldehydes under solvent free conditions
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Neat Et2Zn, Ph2Zn, and highly concentrated Me 2Zn are highly reactive organozinc reagents, which are commercially available in bulk quantities. We here report a catalytic enantioselective Et2Zn, Ph2Zn, and Me2Zn addition to ketones and aldehydes under solvent free or highly concentrated conditions without Ti(Oi-Pr)4 as a conventional activator of organozinc reagents. The desired optically active tertiary and secondary alcohols were obtained in good yield with high enantioselectivity when compared to the conventional solvent-use conditions. From the viewpoint of ecological and environmental reasons in green chemistry, this catalysis would be practical for not only academic but also industrial use.
- Hatano, Manabu,Mizuno, Tomokazu,Ishihara, Kazuaki
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scheme or table
p. 4417 - 4424
(2011/08/06)
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- Full chirality transfer in the conversion of secondary alcohols into tertiary boronic esters and alcohols using lithiation-borylation reactions
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New conditions, full transfer: Using MgBr2/MeOH as an additive now provides essentially 100 % retention of configuration in the lithiation-borylation reaction, thus leading to tertiary boronic esters (or tertiary alcohols) with exceptionally hi
- Bagutski, Viktor,French, Rosalind M.,Aggarwal, Varinder K.
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supporting information; experimental part
p. 5142 - 5145
(2010/10/20)
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- PHOSPHOROAMIDE COMPOUND, METHOD FOR PRODUCING THE SAME, LIGAND, COMPLEX, CATALYST, AND METHOD FOR PRODUCING OPTICALLY ACTIVE ALCOHOL
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Disclosed is a method for highly efficiently obtaining an optically active alcohol from a carbonyl compound highly enantioselectively. Also disclosed is a ligand used in such a method. Specifically, an optically active alcohol is obtained by reacting a ca
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Page/Page column 19; 20
(2009/12/23)
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- Enantioselective addition of organozinc reagents to ketones catalyzed by grafted isoborneolsulfonamide polymers and titanium isopropoxide
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The catalytic enantioselective addition of different organozinc reagents, such as diethylzinc, or in situ generated phenylzinc derivatives to simple aryl methyl ketones was accomplished using titanium tetraisopropoxide and a polymeric ligand grafted with
- Forrat, Vicente J.,Ramon, Diego J.,Yus, Miguel
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scheme or table
p. 65 - 67
(2009/06/18)
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- Toward the continuous-flow synthesis of chiral tertiary alcohols by enantioselective addition of organozinc reagents to ketones using nanosize isoborneol ligands
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The catalytic enantioselective addition of different organozinc reagents, such as alkyl or in situ generated phenylzinc derivatives to simple aryl ketones, was accomplished using titanium tetraisopropoxide and chiral ligands derived from trans-1-arenesulf
- Forrat, Vicente J.,Ramon, Diego J.,Yus, Miguel
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p. 537 - 541
(2008/09/21)
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- Asymmetric addition of diethylzinc to ketones promoted by tartaric acid derivatives
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The preparation of new sulfonamide ligands derived from L-tartaric acid and camphor sulfonyl chloride are described. The employment in the titanium tetraisopropoxide-promoted enantioselective addition of diethylzinc to ketones has been studied. The best enantiomeric excess is up to 99% with 7 mol% catalyst loading at room temperature. Copyright Taylor & Francis Group, LLC.
- Hui, Ailing,Zhang, Jintang,Wang, Zhiyong
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p. 2374 - 2384
(2008/09/21)
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- Highly active chiral phosphoramide-Zn(II) complexes as conjugate acid-base catalysts for enantioselective organozinc addition to ketones
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(Chemical Equation Presented) A highly efficient enantioselective organozinc (R2Zn) addition to ketones catalyzed by chiral phosphoramide-Zn(II) complexes (1-10 mol %) has been developed. These complexes serve as conjugate Lewis acid-Lewis base
- Hatano, Manabu,Miyamoto, Takashi,Ishihara, Kazuaki
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p. 4535 - 4538
(2008/03/12)
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- Kinetic resolution of hydroperoxides with enantiopure phosphines: Preparation of enantioenriched tertiary hydroperoxides
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An efficient reductive kinetic resolution strategy capable of accessing optically active tertiary hydroperoxides is reported. Readily accessible tertiary hydroperoxides are resolved with commercially available (R)- or (S)-xylyl-PHANEPHOS with selectivity factors as large as 37. The resulting bis(phosphine oxide) can be recycled in high yields. The isolated mono(phosphine oxide) intermediate resolved hydroperoxides with the same selectivity as the parent bisphosphine. Copyright
- Driver, Tom G.,Harris, Jason R.,Woerpel
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p. 3836 - 3837
(2008/02/13)
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- Trans-1-sulfonylamino-2-isoborneolsulfonylaminocyclohexane derivatives: Excellent chiral ligands for the catalytic enantioselective addition of organozinc reagents to ketones
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The catalytic enantioselective addition of different organozinc reagents (such as alkyl and aryl derivatives or in situ generated aryl, allyl alkenyl, and alkynyl derivatives obtained through different transmetallation processes) to simple ketones has bee
- Forrat, Vicente J.,Prieto, Oscar,Ramon, Diego J.,Yus, Miguel
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p. 4431 - 4445
(2008/02/08)
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- A new chiral sulfonamide ligand based on tartaric acid: synthesis and application in the enantioselective addition of diethylzinc to aldehydes and ketones
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A new sulfonamide ligand based on l-tartaric acid was synthesized and was employed as a chiral ligand in the enantioselective addition of diethylzinc to aldehydes, giving rise to the best enantiomeric excess up to 83% with 5 mol % of catalyst loading. Moreover, the addition of diethylzinc to ketones can also be achieved with good to excellent enantioselectivities by employing 7 mol % of the catalyst under mild conditions.
- Hui, Ailing,Zhang, Jintang,Fan, Jinmin,Wang, Zhiyong
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p. 2101 - 2107
(2007/10/03)
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- Polymer supported trans-1-phenylsulfonylamino-2-isoborneolsulfonylaminocyclohexane ligand for the titanium catalyzed organozinc addition to ketones
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The catalytic enantioselective addition of different organozinc reagents, such as diethylzinc, or in situ generated phenylzinc derivatives to simple ketones was accomplished using titanium tetraisopropoxide and supported chiral ligands derived from trans-
- Forrat, Vicente J.,Ramon, Diego J.,Yus, Miguel
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p. 2054 - 2058
(2007/10/03)
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- Catalytic asymmetric addition of alkylzinc and functionalized alkylzinc reagents to ketones
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(Chemical Equation Presented) We describe our full report of the catalytic asymmetric addition of simple and functionalized dialkylzinc reagents to a broad range of saturated ketones and enones. The functionalized organozinc reagents contain esters, silyl
- Jeon, Sang-Jin,Li, Hongmei,Garcia, Celina,LaRochelle, Lynne K.,Walsh, Patrick J.
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p. 448 - 455
(2007/10/03)
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- A green chemistry approach to a more efficient asymmetric catalyst: Solvent-free and highly concentrated alkyl additions to ketones
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There is a great demand for development of catalyst systems that are not only efficient and highly enantioselective but are also environmentally benign. Herein we report investigations into the catalytic asymmetric addition of alkyl and functionalized alk
- Jeon, Sang-Jin,Li, Hongmei,Walsh, Patrick J.
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p. 16416 - 16425
(2007/10/03)
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- Chiral tertiary alcohols from a trans-1-arenesulfonyl-amino-2- isoborneolsulfonylaminocyclohexane-catalyzed addition of organozincs to ketones
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The catalytic enantioselective addition of different organozinc reagents, such as alkyl, or in situ generated aryl, allyl, alkenyl and alkynyl derivatives to simple aryl ketones, was accomplished using titanium tetraisopropoxide and chiral ligands derived from 1-arenesulfonylamino-2- isoborneolsulfonylamidocyclohexane, giving the corresponding tertiary alcohols with enantioselectivities up to ≥99%. A simple and efficient procedure for the synthesis of the disulfonamide ligands used is described.
- Forrat, Vicente J.,Ramon, Diego J.,Yus, Miguel
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p. 3341 - 3344
(2007/10/03)
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- trans-1,2-diaminocyclopentane-based catalyst for the asymmetric addition of alkyl-, aryl-, and vinyl groups to ketones
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The catalytic asymmetric addition of ethyl-, phenyl-, and 1-hexenyl groups to ketones is reported. The new catalyst, generated from titanium wopropoxide and a bis(sulfonamide) diol ligand based on frans-1,2-diaminocyclopentane, gives good to excellent ena
- De Parrodi, Cecilia Anaya,Walsh, Patrick J.
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p. 2417 - 2420
(2007/10/03)
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- Stereoselectivity of Grignard reaction in the presence of chiral podands and crown ethers
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Reactions of ethylmagnesium bromide with benzaldehyde and acetophenone in toluene proceed stereoselectively in the presence of catalytic amounts of chiral podands and crown ethers. Under catalytic conditions theyield of the corresponding alcohols is nearl
- Luk'yanenko,Lobach,Leus
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p. 273 - 277
(2007/10/03)
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- Synthesis of new C2-symmetrical bis(hydroxycamphorsulfonamide) ligands and their application in the enantioselective addition of dialkylzinc reagents to aldehydes and ketones
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The preparation of several C2-symmetric disulfonamides derived from chiral camphorsulfonyl chloride and different diamines (with or without stereogenic elements) is described. Their use in the titanium tetraisopropoxide-promoted enantioselective addition of dialkylzinc reagents to aldehydes has been tested, the best enantiomeric excess being up to 76%. Moreover, the unusual addition of dialkylzinc reagents to ketones can also be achieved with excellent enantioselectivity (up to 92% e.e.) using this type of ligand. When using para-substituted phenones as electrophiles, the enantiomeric excess of the resulting tert-alcohol is independent of the electronic properties of the group attached to the aromatic ring of the phenone. In the case of using more hindered ketones the enantioselectivity is lower, so indicating a steric influence in the reaction.
- Yus, Miguel,Ramon, Diego J.,Prieto, Oscar
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p. 1103 - 1114
(2007/10/03)
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- CATALYSTS, METHODS FOR MAKING SAID CATALYSTS, AND METHODS FOR MAKING CHIRAL COMPOUNDS WITH HIGH ENANTIOSELECTIVITY
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The present invention relates to compounds useful as catalysts in asymmetric synthesis of chiral compounds, methods for the synthesis of said catalysts, and methods for synthesizing chiral compounds with high enantioselectivity.
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Page/Page column 10
(2010/01/31)
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- A convenient method for the preparation of inverted tert-alkyl carboxylates from chiral tert-alcohols by a new type of oxidation-reduction condensation using 2,6-dimethyl-1,4-benzoquinone
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Oxidation-reduction condensation using in situ-formed alkoxydiphenylphosphines, 2,6-dimethyl-1,4-benzoquinone, and carboxylic acids provided a new and efficient method for the preparation of inverted tert-alkyl carboxylates from various chiral tertiary al
- Mukaiyama, Teruaki,Shintou, Taichi,Fukumoto, Kentaro
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p. 10538 - 10539
(2007/10/03)
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- A practical catalytic asymmetric addition of alkyl groups to ketones
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Many catalysts will promote the asymmetric addition of alkylzinc reagents to aldehydes. In contrast, there are no reports of additions to ketones that are both general and highly enantioselective. We describe herein a practical catalytic asymmetric additi
- Garcia, Celina,LaRochelle, Lynne K.,Walsh, Patrick J.
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p. 10970 - 10971
(2007/10/03)
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- Highly enantioselective addition of dialkylzinc reagents to ketones promoted by titanium tetraisopropoxide
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The preparation of several 1,2-bis(hydroxycamphorsulfonamido)cyclohexenes from the corresponding 1,2-cyclohexenediamine and camphorsulfonyl chloride is described. The use of these ligands to promote the enantioselective addition of dialkylzinc to ketones
- Yus, Miguel,Ramon, Diego J.,Prieto, Oscar
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p. 2291 - 2293
(2007/10/03)
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- First enantioselective addition of diethylzinc and dimethylzinc to prostereogenic ketones catalysed by camphorsulfonamide-titanium alkoxide derivatives
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The reaction of diethylzinc or dimethylzinc with prostereogenic ketones, in the presence of a stoichiometric amount of titanium tetraisopropoxide and a catalytic amount (20%) of camphorsulfonamide derivatives as chiral ligands leads to the formation of the corresponding enantioenriched tert-alcohols with enantiomeric ratios up to 94.5 : 5.5. the best results were obtained when phenones are used as substrates independently of the dialylzinc reagent. The enantioselectivity shows a linear relationship with the enantiomeric excess of the ligand and seems to be independent of the reaction yield. A tentative catalytic cycle and mechanistic model are proposed for this new reaction.
- Ramon, Diego J.,Yus, Miguel
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p. 5651 - 5666
(2007/10/03)
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- First enantioselective addition of dialkylzinc to ketones promoted by titanium(IV) derivatives
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The reaction of dimethyl or diethylzinc with ketones in the presence of a stoichiometric amount of titanium tetraisopropoxide and a catalytic amount (20 mol %) of camphorsulfonamide derivatives as chiral ligands leads to the formation of the corresponding
- Ramon, Diego J.,Yus, Miguel
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p. 1239 - 1242
(2007/10/03)
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- Epoxidation and oxygen insertion into alkane CH bonds by dioxirane do not involve detectable radical pathways
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The dimethyldioxirane oxidation of α-methylstyrene, trans-cyclooctene, and 1-vinyl-2,2-diphenylcyclopropane gave, under all reaction conditions employed, the corresponding epoxides in high yields. No radical products from allylie oxidation, from trans/cis isomerization, or from cyclopropylcarbinyl rearrangement (radical clock) were observed. Even for these alkenes, which are prone to radical reactions, the previously established electrophilic concerted mechanism applies, rather than the recently proposed radical mechanism. The selective hydroxylation of (-)-2-phenylbutane by dimethyldioxirane gave only (-)-2-phenylbutan-2-ol with complete retention of configuration and no loss of optical purity. Thus, a radical-chain oxidation is also discounted in the oxygen insertion into hydrocarbon C H bonds for dioxiranes.
- Adam, Waldemar,Curci, Ruggero,D'Accolti, Lucia,Dinoi, Anna,Fusco, Caterina,Gasparrini, Francesco,Kluge, Ralph,Paredes, Rodrigo,Schulz, Manfred,Smerz, Alexander K.,Veloza, L. Angela,Weinkoetz, Stephan,Winde, Roland
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p. 105 - 109
(2007/10/03)
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- (5aS,10aS)-Octahydro-1H,5H-dipyrrolopyrazine "DPP" as Auxiliary Reagent for Enantioselctive Alkylations of Prochiral Carbonyl Compounds
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In the presence of one equivalent of the title compound "DPP" (1) prochiral carbonyl compounds 2 react with Grignard reagents 3 in THF to form enantioselectively alcohols 4 with up to 98percent ee, whereas the addition of one equivalent of triethylamine yields the opposite enantiomers with up to 97percent ee.The optimal molar ratio of 1 and magnesium reagent 3 was determined by cryoscopic measurements.Asymmetric induction is supposed to arise from transition states involving monomeric octahedral complexes of Grignard reagent, chiral solvent, and carbonyl compound.DPP (1) also catalyses Grignard alkylations, because a tenth of its stochiometric amount gives an enantiomeric eccess four times more than as expected.Prepared from (S)-proline, only the boat conformation of 1 induces the observed selectivity as detected by 13C-NMR spectroscopy. - Key Words: Dipyrrolopyrazine, (5aS,10aS)-octahydro-1H,5H- / 1,2-Addition, enantioselective / Grignard reagents / Chiral solvent /Cryoscopic measurements
- Zadel, Guido,Breitmaier, Eberhard
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p. 1323 - 1326
(2007/10/02)
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- Highly enantioselective addition of primary alkyl Grignard reagents to carbocyclic and heterocyclic arylketones in the presence of magnesium TADDOLate preparative and mechanistic aspects
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In the presence of equimolar amounts of the Mg alkoxide from α,α,α',α'-tetraphenyl-2,2-dimethyl-1,3-dioxolan-4,5-dimethanol (a TADDOL) primary Grignard reagents (Et, Pr, Bu, Oct, 3-butenyl) add to carbo- and heteroaromatic methyl ketones in THF at -100°C to give tertiary alcohols of enantiomeric excesses reaching values above 98%. The scope and limitation of the method are investigated. The reaction, which occurs in a vigorously stirred heterogeneous mixture, give best results in the absence of steric hindrance of the reacting centers; Grignard reagents made from alkyl bromides are superior to those obtained from chlorides; there is a perfect linear relationship between the ee of the TADDOL and of the product 2-phenyl-2-decanol; those tertiary alcohols of which the absolute configuration is known, are formed by nucleophilic attack from the Re face of the keto carbonyl groups. Three tentative mechanistic models for the stereochemical course of the reaction are discussed.
- Weber, Beat,Seebach, Dieter
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p. 6117 - 6128
(2007/10/02)
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- HIGHLY ENANTIOSELECTIVE ADDITION OF (S)-LITHIOMETHYL 1-NAPHTHYL SULFOXIDE TO KETONES
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The anion of (S)-(-)-methyl 1-naphthyl sulfoxide reacts enantioselectively with alkyl phenyl ketones to give (SsSc)-β-hydroxysulfoxides with diastereomeric excess (de) up to 100percent.Optical pure (S)-tertiary alcohols are prepared by desulfurization of the corresponding diastereomers.
- Sakuraba, Hidetake,Ushiki, Shigeru
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p. 5349 - 5352
(2007/10/02)
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- Diastereofacial Control in the Reaction of Chiral α-Amino Ketones with Several Organometallics
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The addition reaction of organometallics to chiral α-amino ketones, prepared from α-halo ketones and (S)-2-methoxymethylpyrrolidine as a chiral auxiliary, gave different diastereomers of chiral amino alcohols depending on the difference of coordination ab
- Fujisawa, Tamotsu,Funabora, Makoto,Ukaji, Yutaka,Sato, Toshio
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- Asymmetric Syntheses Based on 1,3-Oxathianes. 2. Synthesis of Chiral Tertiary α-Hydroxy Aldehydes, α-Hydroxy Acids, Glycols (RR'C(OH)CH2OH), and Carbinols (RR'C(OH)CH3) in High Enantiomeric Purity
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A chiral 1,3-oxathiane (5) prepared from (+)-pulegone in three steps is converted to diastereomerically pure equatorial 2-acyl derivatives by lithiation, condensation with aldehydes, and Me2SO oxidation.Reaction of the resulting ketones with Grignard reagents at -78 deg C again proceeds highly stereoselectively (diastereomer excess generally above 90percent) according to Cram's rule (cyclic model).The resulting tertiary carbinols when cleaved with NCS/AgNO3 give chiral tertiary α-hydroxy aldehydes, RR'C(OH)CHO, plus a mixture of epimeric sultines which may be readily reconverted to the starting oxathiane.The hydroxy aldehydes have been oxidized to chiral tertiary α-hydroxy acids, RR'C(OH)CO2H, and reduced to primary-tertiary glycols, RR'C(OH)CH2OH, and further to tertiary carbinols, RR'C(OH)CH3, all with over 90percent ee.The opposite enantiomers of these compounds (again >90percent ee) may be obtained by starting with a diastereomeric 1,3-oxathiane (6), also available from (+)-pulegone.The configurations of the chiral products may be deduced from the manner of preparation and the assumption that Cram's rule is valid and agree with prior assignments in the literature.
- Lynch, Joseph E.,Eliel, Ernest L.
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p. 2943 - 2948
(2007/10/02)
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- Sulfoximine-Mediated Syntheses of Optically Active Alcohols
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Optically active β-hydroxy sulfoximines were prepared, as diastereomeric pairs, by the addition the lithium derivative of optically active N,S-dimethyl-S-phenylsulfoximine to prochiral ketones and aldehydes.The ketone adducts after separation by medium-pr
- Johnson, Carl R.,Stark, Charles J.
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p. 1193 - 1196
(2007/10/02)
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