- Synthesis and olfactory evaluation of optically active β-alkyl substituted γ-lactones and whiskey lactone analogues
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Optically active β-alkyl substituted γ-lactones and whiskey lactone analogues were synthesized, and the odor properties were evaluated. During the preparation of the chiral intermediates, we found good reaction conditions for the highly enantioselective esterification of 3-arylmethyl-2-methyl-1-propanols to kinetically resolve them. The results of the olfactory evaluations of the synthesized lactones revealed that the alkyl groups on the γ-lactone rings played an important role for the odor profiles.
- Kato, Daiki,Kawasaki, Masashi,Morita, Yuko,Okada, Takuya,Tanaka, Yasuo,Toyooka, Naoki
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- Iridium catalysts with Chiral bicyclic pyridine-phosphane ligands for the asymmetric hydrogenation of olefins
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New bicyclic pyridine-phosphane ligands were prepared, and their iridium complexes were evaluated in asymmetric hydrogenation of trisubstituted olefins with non-coordinating and weakly coordinating substituents. The iridium catalysts showed high reactivity and enantioselectivity for both types of olefins. New pyridine-derived N,P-chelated iridium catalysts were prepared and evaluated in the asymmetric hydrogenation of trisubstituted olefins. High conversions and enantioselectivities were obtained. Copyright
- Quan, Xu,Parihar, Vijay Singh,Bera, Milan,Andersson, Pher G.
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p. 140 - 146
(2014/01/06)
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- A theoretically-guided optimization of a new family of modular P,S-ligands for iridium-catalyzed hydrogenation of minimally functionalized olefins
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A library of modular iridium complexes derived from thioether-phosphite/phosphinite ligands has been evaluated in the asymmetric iridium-catalyzed hydrogenation of minimally functionalized olefins. The modular ligand design has been shown to be crucial in finding highly selective catalysts for each substrate. A DFT study of the transition state responsible for the enantiocontrol in the Ir-catalyzed hydrogenation is also described and used for further optimization of the crucial stereodefining moieties. Excellent enantioselectivities (enantiomeric excess (ee) values up to 99%) have been obtained for a range of substrates, including E- and Z-trisubstituted and disubstituted olefins, α,β-unsaturated enones, tri- and disubstituted alkenylboronic esters, and olefins with trifluoromethyl substituents.
- Margalef, Jèssica,Caldentey, Xisco,Karlsson, Erik A.,Coll, Mercè,Mazuela, Javier,Pàmies, Oscar,Diéguez, Montserrat,Pericàs, Miquel A.
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supporting information
p. 12201 - 12214
(2015/03/31)
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- A modular furanoside thioether-phosphite/phosphinite/ phosphine ligand library for asymmetric iridium-catalyzed hydrogenation of minimally functionalized olefins: Scope and limitations
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A highly modular furanoside thioether-phosphite/phosphinite/phosphine ligand library has been synthesized for the iridium-catalyzed asymmetric hydrogenation of minimally functionalized olefins. These ligands can be prepared efficiently from easily accessible D-(+)-xylose. We found that their effectiveness at transferring the chiral information in the product can be tuned by correctly choosing the ligand components. Enantioselectivities were therefore excellent (ees up to 99%) in a wide range of E- and Z-trisubstituted alkenes using 5-deoxyribofuranoside thioether-phosphite ligands. It should be pointed out that these catalysts are also very tolerant to the presence of a neighbouring polar group. For 1,1-disubstituted substrates, both enantiomers of the hydrogenation product can be obtained in high enantioselectivities simply by changing the configuration of the biaryl phosphite moiety. The asymmetric hydrogenation was also performed using propylene carbonate as solvent, which allowed the iridium catalysts to be reused while maintaining the excellent enantioselectivities. Copyright
- Coll, Mercedes,Pamies, Oscar,Dieguez, Montserrat
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supporting information
p. 143 - 160
(2013/03/28)
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- A phosphite-pyridine/iridium complex library as highly selective catalysts for the hydrogenation of minimally functionalized olefins
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A modular library of readily available phosphite-pyridine ligands has been successfully applied for the first time in the iridium-catalyzed asymmetric hydrogenation of a broad range of minimally functionalized olefins. The modular ligand design has been shown to be crucial in finding highly selective catalytic systems for each substrate. Excellent enantioselectivities (ees up to 99%) have therefore been obtained in a wide range of E- and Z-trisubstituted alkenes, including more demanding triaryl-substituted olefins and dihydronaphthalenes. This good performance extends to the very challenging class of terminal disubstituted olefins, and to olefins containing neighbouring polar groups (ees up to 99%). Both enantiomers of the reduction product can be obtained in excellent enantioselectivities by simply changing the configuration of the carbon next to the phosphite moiety. The hydrogenations were also performed using propylene carbonate as solvent, which allowed the iridium catalyst to be reused and maintained the excellent Copyright
- Mazuela, Javier,Pamies, Oscar,Dieguez, Montserrat
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supporting information
p. 2569 - 2583
(2013/10/21)
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- Expanded scope of the asymmetric hydrogenation of minimally functionalized olefins catalyzed by iridium complexes with phosphite-thiazoline ligands
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We have replaced the oxazoline group with a thiazoline moiety in one of the most successful of the phosphite-oxazoline ligand families for the Ir-catalyzed hydrogenation of minimally functionalized olefins. A small but structurally important library of Ir phosphite-thiazoline precatalysts (Ir-L1-L2a-e) has been developed by changing the substituents/configurations at the biaryl phosphite group. We found that the replacement of the oxazoline with a thiazoline moiety in the ligand design is beneficial in terms of substrate scope.
- Mazuela, Javier,Pamies, Oscar,Dieguez, Montserrat
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p. 2410 - 2417
(2013/08/23)
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- Chiral imidate-ferrocenylphosphanes: Synthesis and application as P,N-ligands in iridium(i)-catalyzed hydrogenation of unfunctionalized and poorly functionalized olefins
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A small library of chiral imidate-ferrocenylphosphane ligands was efficiently synthesized (8 examples) and evaluated in the iridium(i)-catalyzed hydrogenation of unfunctionalized and poorly functionalized olefins. These catalysts perform very well in a range of examples (yields and ee's up to 100%).
- Bert, Katrien,No?l, Timothy,Kimpe, Wim,Goeman, Jan L.,Van Der Eycken, Johan
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p. 8539 - 8550
(2013/01/15)
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- The application of pyranoside phosphite-pyridine ligands to enantioselective Ir-catalyzed hydrogenations of highly unfunctionalized olefins
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Eight (biaryl)phosphite/pyridine ligands 1-2a-d have been prepared by the modular functionalization of positions C-2 and C-3 of two d-glucopyranoside backbones. The chiral ligands were examined in the iridium-catalyzed asymmetric hydrogenation of poorly functionalized alkenes, as a function of the relative position of the coordinating groups and the geometric properties of the biaryl phosphite moieties. Enantiomeric excesses of up to 90% were achieved in the hydrogenation of E-2-(4-methoxyphenyl)-2-butene by using 1a and 1c, which seemingly combine the beneficial effect of the phosphite at the 2-position with the matching (Rax)-configuration of their encumbered biaryl substituents. The results of the hydrogenation of more challenging substrates, such as Z-trisubstituted alkenes, alkenes with a neighboring polar group or demanding 1,1-di-substituted alkenes, generally confirmed this trend, and in some significant cases, the chiral hydrogenated products were isolated with ees of 65-79%. 2012 Elsevier Ltd.
- Margalef, Jessica,Lega, Matteo,Ruffo, Francesco,Pamies, Oscar,Dieguez, Montserrat
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experimental part
p. 945 - 951
(2012/10/07)
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- New monoterpene-derived phosphinopyridine ligands and their application in the enantioselective iridium-catalyzed hydrogenation
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Pyridine derivatives with a phosphine or phosphinite pendant (1-11) have been synthesized from (+)-α-pinene, (-)-isopinocampheol, and/or (+)-camphor via Kro?hnke annulation or another annulation method as the key step for the construction of the pyridine nucleus. The iridium complex of 6 proved to catalyze hydrogenation of the prochiral unfunctionalized alkene 44 with 94% ee, whereas the complex of 2 was most efficient in the hydrogenation of the cinnamyl-type ester 45 (83% ee).
- Chelucci, Giorgio,Marchetti, Mauro,Malkov, Andrei V.,Friscourt, Frédéric,Swarbrick, Martin E.,Ko?ovsky, Pavel
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experimental part
p. 5421 - 5431
(2011/08/06)
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- Adaptative biaryl phosphite-oxazole and phosphite-thiazole ligands for asymmetrie Ir-catalyzed hydrogenation of alkenes
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A library of readily available phosphite-oxazole/thiazole ligands (L1a-g-L7a-g) was applied in the Ir-catalyzed asymmetric hydrogenation of several largely unfunctionalized E- and Z-trisubstituted and 1,1-disubstituted terminal alkenes. The ability of the catalysts to transfer chiral information to the product could be tuned by choosing suitable ligand components (bridgelength, the substituents in the heterocyclic ring and the alkyl backbone chain, the configuration of the ligand backbone, and the substituents/ configurations in the biaryl phosphite moiety),so that enantioselectivities could be maximized for each substrate as required. Enantioselectivities were therefore excellent (enantiomeric excess (ee) values up to >99%) for a wide range of E- and Z-trisubstituted and 1,1-disubstituted terminal alkenes. The biaryl phosphite moiety was a very advantageous ligand component in terms of substrate versatility.
- Diéguez, Montserrat,Mazuela, Javier,Paptchikhine, Alexander,Pàmies, Oscar,Andersson, Pher G.
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experimental part
p. 4567 - 4576
(2010/08/07)
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- A molecular modelling approach to rationalize the stereochemical outcome of the Burkholderia cepacia lipase-catalyzed transesterification of aromatic primary alcohols with vinyl esters with different chain lengths in chloroform
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The Burkholderia cepacia lipase-catalyzed transesterification of 2-methyl-3-phenyl-1-propanol with vinyl esters proceeds with high enantioselectivity independently of the acyl chain length and the low enantioselectivity of the same reaction with 2-phenyl-1-propanol is not affected by chain length of the vinyl esters. A molecular modelling approach has been developed in order to rationalize the enzymatic results.
- Santaniello, Enzo,Casati, Silvana,Ciuffreda, Pierangela,Meroni, Giuseppe,Pedretti, Alessandro,Vistoli, Giulio
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experimental part
p. 1833 - 1836
(2009/12/26)
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- Asymmetric hydrogenation and allylic substitution reaction with novel chiral pinene-derived N,P-ligands
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A series of new chiral tetrahydroquinoline ligands, derived from chiral α-pinene, were successfully synthesized. Iridium and palladium complexes of these ligands were proven to be efficient catalysts for enantioselective hydrogenation and allylic substitution reactions with moderate to excellent enantioselectivities (90-95% ee) and high yields.
- Meng, Xiangyan,Li, Xinsheng,Xu, Dongcheng
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experimental part
p. 1402 - 1406
(2009/12/01)
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- Iridium catalysts with chiral imidazole-phosphine ligands for asymmetric hydrogenation of vinyl fluorides and other olefins
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New chiral bidentate imidazole-phosphine ligands have been prepared and evaluated for the iridium-catalysed asymmetric hydrogenation of olefins. The imidazole-phosphine-ligated iridium catalysts hydrogenated trisubstituted olefins with the same sense of enantiodiscrimination as known iridium catalysts possessing oxazole and thiazole as N-donors. The imidazole-based catalysts were shown to hydrogenate vinyl fluorides, in some cases with the highest ee values published to date.
- Kaukoranta, Paeivi,Engman, Mattias,Hedberg, Christian,Bergquist, Jonas,Andersson, Pher G.
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supporting information; experimental part
p. 1168 - 1176
(2009/05/27)
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- Chiral pyranoside phosphite-oxazolines: A new class of ligand for asymmetric catalytic hydrogenation of alkenes
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We have described the first successful application of a phosphite-oxazoline ligand library in the asymmetric Ir-catalyzed hydrogenation of several unfunctionalized olefins. The introduction of a bulky biaryl phosphite moiety in the ligand design is highly adventitious in the product outcome. By carefully selecting the ligand components, we obtained high activities (TOFs up to >1500 mol·(mol·h)-1 at 1 bar of H2) and enantioselectivities (ee values up to >99%) and, at the same time, show a broad scope for different substrate types. So, this is an exceptional ligand class that competes favorably with a few other ligand series that also provide high ee values for tri- and disubstituted substrate types. Copyright
- Dieguez, Montserrat,Mazuela, Javier,Pamies, Oscar,Verendel, J. Johan,Andersson, Pher G.
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p. 7208 - 7209
(2008/12/21)
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- Zirconium-catalyzed asymmetric carboalumination of alkenes: ZACA-lipase-catalyzed acetylation synergy
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ZACA-lipase-catalyzed acetylation tandem reactions provide highly efficient and selective routes to either (R)- or (S)-2-methyl-1-alkanols, making, for the first time, the ZACA-based asymmetric synthesis of 2-methyl-1-alkanols widely applicable and satisfactory.
- Huang, Zhihong,Tan, Ze,Novak, Tibor,Zhu, Gangguo,Negishi, Ei-Ichi
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p. 539 - 545
(2008/02/08)
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- CHIRAL LIGANDS AND THEIR TRANSITION METAL COMPLEXES
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The invention relates to chiral phosphorus compounds and their transition metal complexes, in addition to the use of said transition metal complexes, in particular in asymmetric syntheses.
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Page/Page column 34-36
(2010/02/09)
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- Rationally designed ligands for asymmetric iridium-catalyzed hydrogenation of olefins
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A new class of chiral N,P-ligands for the Ir-catalyzed asymmetric hydrogenation of aryl alkenes has been developed. These new ligands proved to be highly efficient and tolerates a broad range of substrates. The enantiomeric excesses are in the range of the best ever reported. The results can be rationalized with the proposed selectivity model. Copyright
- Kaellstroem, Klas,Hedberg, Christian,Brandt, Peter,Bayer, Annette,Andersson, Pher G.
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p. 14308 - 14309
(2007/10/03)
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- t-BuOK-mediated hydrophosphination of functionalized alkenes: A novel synthesis of chiral P,N- and P,P-ligands
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A novel synthesis of effective chiral P,N- and P,P-ligands has been developed by using a t-BuOK-mediated hydrophosphination of chiral alkenylpyridines and alkenylphosphine oxides. Ir complexes of chiral P,N-ligands 1 and 3 gave high enantioselectivities for the hydrogenation of (Z)-α-(acetamido)cinnamate 25 and (E)-1,2-diphenylpropene leading to the hydrogenated products with up to 97% ee.
- Bunlaksananusorn, Tanasri,Knochel, Paul
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p. 4595 - 4601
(2007/10/03)
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- Highly enantioselective kinetic resolution of primary alcohols of the type Ph-X-CH(CH3)-CH2OH by Pseudomonas cepacia lipase: Effect of acyl chain length and solvent
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Although lipase from Pseudomonas cepacia (PCL) shows high enantioselectivity towards many secondary alcohols, it usually exhibits only low to moderate enantioselectivity towards primary alcohols. To increase this enantioselectivity, we optimised the reaction conditions for the PCL-catalysed hydrolysis of esters of three chiral primary alcohols: 2-methyl-3-phenyl-1- propanol 1, 2-phenoxy-1-propanol 2 and solketal 3. The enantioselectivity towards 1-acetate increased from E=16 to 38 upon changing the solvent from ethyl ether/phosphate buffer to 30% n-propanol in phosphate buffer and increased again to E ≥190 upon changing the substrate from 1-acetate to 1-heptanoate. The same changes increased the enantioselectivity towards alcohol 2 from E=17 to 70, but did not significantly increase the enantioselectivity towards alcohol 3. The best solvent was similar to the solvent used to crystallise the open form of PCL and likely stabilises the open form of PCL. This stabilisation may increase the enantioselectivity by removing kinetic contributions from a non-enantioselective lid-opening step. We determined the kinetic contribution of the lid-opening step by measuring the interfacial activation of PCL. The activation energy for the PCL-catalysed hydrolysis of ethyl acetate was at least 2.6 kcal/mol lower in the presence of a water-organic solvent interface.
- Mezzetti, Alessandra,Keith, Curtis,Kazlauskas, Romas J.
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p. 3917 - 3924
(2007/10/03)
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- New P, N ligands for asymmetric Ir-catalyzed reactions
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Chiral Ir complexes such as 1 catalyze the hydrogenation of (E)-1, 2-diphenylpropene at 1 bar of H2 to give (5)-1, 2-diphenylpropane with up to 95% ee and full conversion (see scheme). Methyl (Z)-α -(acetamido)cinnamate underwent enantioselective hydrogenation under similar conditions to the corresponding amino acid derivative with up to 96% ee. BARF = tetrakis(3,5-bis(trifluoromethyl)phenyl)borate, cod = 1, 5-cyclooctadiene.
- Bunlaksananusorn, Tanasri,Polborn, Kurt,Knochel, Paul
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p. 3941 - 3943
(2007/10/03)
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- Kinetic resolution of primary 2-methyl-substituted alcohols via Pseudomonas cepacia lipase-catalysed enantioselective acylation
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The enantioselectivities of lipases from Pseudomonas cepacia (PFL, Amano PS, etc.) towards a series of primary 2-methyl-substituted alcohols using vinyl acetate as the acyl donor in transesterifications in organic solvents were studied. In terms of enantioselectivity, the best results were found for 3-aryl-2-methylpropan-1-ols with enantiomeric ratios (E-values) over 100 in most cases, whereas other 3-substituted primary 2-methylpropan-1-ols generally displayed lower enantioselectivities: 3-cycloalkyl-2-methylpropan-1-ols (E ≈ 20) and 2-methylalkan-1-ols (E ≈ 10). Moving the aryl group closer or further away from the chiral centre resulted in low enantioselectivities: 2-arylpropan-1-ols (E 10), 2-methyl-4-(2-thienyl)butan-1-ol (E = 12), 2-methyl-5-(2-thienyl)pentan-1-ol (E = 3.2) and 2-methyl-6-(2-thienyl)hexan-1-ol (E = 3.8).
- Nordin, Ove,Nguyen, Ba-Vu,Voerde, Carin,Hedenstroem, Erik,Hoegberg, Hans-Erik
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p. 367 - 376
(2007/10/03)
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- Enzymatic preparation of optically active fungicide intermediates in aqueous and in organic media
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Pure stereoisomers of two new triazole and morpholine fungicides have been prepared starting from enzymatically synthesized chiral alcohol intermediates.Two resolution strategies compared are: lipase-catalyzed hydrolysis of corresponding acetates in water and lipase-catalyzed transesterification of alcohols in organic solvents.The antifungal activity of optically pure enantiomers of the synthesized fungicides investigated in vitro and in vivo against a variety of fungi, show an activity ratio (R-form/S-form) up to 400.
- Bianchi, Daniele,Cesti, Pietro,Golini, Paolo,Spezia, Sandro,Garavaglia, Carlo,Mirenna, Luigi
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p. 176 - 180
(2007/10/02)
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- SYNTHESIS OF CHIRAL BUILDING BLOCKS FOR SELECTIVE ADENOSINE RECEPTOR AGENTS. LIPASE-CATALYZED RESOLUTION OF 2-BENZYLPROPANOL AND 2-BENZYLPROPIONIC ACID
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Both enantiomers of 2-benzylpropanol and 2-benzylpropinoic acid have been synthesized using a lipase-catalyzed resolution in an organic solvent and in water.
- Delnick, Deborah L.,Margolin, Alexey L.
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p. 6797 - 6798
(2007/10/02)
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