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Search for "prochiral" in Full Text gives 63 result(s) in Beilstein Journal of Organic Chemistry.
Bromine–lithium exchange: An efficient tool in the modular construction of biaryl ligands
Beilstein J. Org. Chem. 2011, 7, 1278–1287, doi:10.3762/bjoc.7.148
- routes to synthetically challenging aryl halide precursors have been devised. A. Alexakis et al. recently achieved a significant breakthrough. They succeeded in the desymmetrization of prochiral polybrominated [32][51] compounds by an asymmetric bromine–lithium exchange in the presence of a
- stoichiometric amount of chiral diamines. An enantiomeric excess of up to 63% was obtained [67]. H. Kagan et al. reported the desymmetrization of prochiral aromatic or vinylic dihalide substrates by halogen–metal exchange in the presence of a stoichiometric amount of diamines, with enantiomeric excess up to 26
A simple and convenient one-pot synthesis of substituted isoindolin-1-ones via lithiation, substitution and cyclization of N'-benzyl-N,N-dimethylureas
Beilstein J. Org. Chem. 2011, 7, 1219–1227, doi:10.3762/bjoc.7.142
- report full details of that work, extend the scope of the reaction and examine the diastereoselectivity of the reaction with prochiral electrophiles. Results and Discussion As noted above, when lithiation of 1 was carried out at 0 °C rather than at −20 °C prior to reaction with an electrophile, lower
Chiral gold(I) vs chiral silver complexes as catalysts for the enantioselective synthesis of the second generation GSK-hepatitis C virus inhibitor
Beilstein J. Org. Chem. 2011, 7, 988–996, doi:10.3762/bjoc.7.111
- of the 1,3-DC employing chiral metallic Lewis bases arises from the blockage of one of the prochiral faces [40]. In this way, our results (in terms of DFT calculations) show that there is only one energetically accessible conformation due to the high substitution of the leucine-derived ylide (Figure
- 3). In this reactive complex there is an effective blockage of the (2re,5si) prochiral face of the ylide. Therefore, the predicted stereochemical outcome corresponds to the exclusive formation of the (2S,4S,5R)-5b cycloadduct, the same as that obtained experimentally. As shown in Figure 3, the
Recent advances in the gold-catalyzed additions to C–C multiple bonds
Beilstein J. Org. Chem. 2011, 7, 897–936, doi:10.3762/bjoc.7.103
Asymmetric synthesis of tertiary thiols and thioethers
Beilstein J. Org. Chem. 2011, 7, 582–595, doi:10.3762/bjoc.7.68
- simple tertiary alcohols is generally achieved by controlling enantiofacial selectivity in nucleophilic attack on a prochiral ketone [10], comparable approaches to tertiary thiols 1 are not practical due to the instability of thioketones, their tendency to undergo nucleophilic attack at sulfur rather
Application of the diastereoselective photodeconjugation of α,β-unsaturated esters to the synthesis of gymnastatin H
Beilstein J. Org. Chem. 2011, 7, 151–155, doi:10.3762/bjoc.7.21
- enantioselective versions. Starting from α-substituted esters 3 in the presence of a catalytic amount of an enantiomerically pure bicyclic amino alcohol 4 – derived from camphor –, the protonation of the prochiral photodienol can be achieved with an ee up to 91% [5]. This value is one of the highest values
Development of dynamic kinetic resolution on large scale for (±)-1-phenylethylamine
Beilstein J. Org. Chem. 2010, 6, 823–829, doi:10.3762/bjoc.6.97
- for their preparation that are applicable on multigram scale. They can be prepared by resolution of amines, hydrogenation of prochiral imines and enamines [1][2], alkylation of prochiral imines [3], aminohydroxylation of alkenes [4], transamination of prochiral ketones [5][6][7], and reductive
- amination of prochiral ketones [8]. Of these methods kinetic resolution using enzymes is often favored due to its simplicity [9][10]. The main disadvantages of kinetic resolution are that only a maximum yield of 50% can be achieved and that the remaining unreacted starting material must be removed from the
Shelf-stable electrophilic trifluoromethylating reagents: A brief historical perspective
Beilstein J. Org. Chem. 2010, 6, No. 65, doi:10.3762/bjoc.6.65
- chiral groups thus giving the possibility to achieve enantioselective trifluoromethylation of prochiral substrates. This is one of the important issues that is only partially solved in fluoro-organic chemistry. Therefore, chiral reagent 18 was designed and synthesized from (1R)-(+)-camphor as shown in
A novel and efficient method to prepare 2-aryltetrahydrofuran-2-ylphosphonic acids
Beilstein J. Org. Chem. 2010, 6, No. 63, doi:10.3762/bjoc.6.63
- from MS and NMR spectral data. The cyclic structures of the end products were verified not only from molecular ion peaks in the mass spectra but also from 1H NMR data, in which three CH2-groups give rise to six chemical shifts. This phenomenon exists if a chiral center (sometimes a prochiral center) is
Concise methods for the synthesis of chiral polyoxazolines and their application in asymmetric hydrosilylation
Beilstein J. Org. Chem. 2010, 6, No. 29, doi:10.3762/bjoc.6.29
- prochiral ketones. In particular, asymmetric catalysis provides organic chemists with a unique tool for their efficient synthesis [23], although none of these are, as yet, optimal [24][25][26]. In recent years, metal-catalyzed hydrosilylation of ketones has been investigated using chiral ligands [27][28][29
- ][30][31][32][33], while enantioselective hydrogenation of prochiral ketones to optically active secondary alcohols is among the most fundamental subjects in modern synthetic chemistry. In this article, with the new polyoxazoline ligands in hand, the Rh-catalyzed hydrosilylation of aromatic ketones was
- alcohols, because the enantioselectivities were determined solely by the chirality of oxazoline rings derived from the chiral amino alcohols. The reduction of various prochiral aryl-substituted ketones was examined in order to evaluate the influence of ligand 2 on Rh(I)-catalyzed asymmetric hydrosilylation
Large- scale ruthenium- and enzyme- catalyzed dynamic kinetic resolution of (rac)-1-phenylethanol
Beilstein J. Org. Chem. 2007, 3, No. 50, doi:10.1186/1860-5397-3-50
- natural products. [1][2][3][4] A few methods have been developed for the enantioselective synthesis of chiral alcohols including catalytic asymmetric hydrogenation [5][6][7][8][9][10][11][12][13][14] and enantioselective hydride addition [15][16] of prochiral ketones, asymmetric dialkylzinc addition to
Conformational rigidity of silicon- stereogenic silanes in asymmetric catalysis: A comparative study
Beilstein J. Org. Chem. 2007, 3, No. 9, doi:10.1186/1860-5397-3-9
- formation occurs between the stereogenic silicon and the prochiral carbon therefore entailing their close proximity. The newly formed stereogenic carbon is directly connected to the former source of chiral information. In contrast, the decisive asymmetrically substituted carbon atom in the alcohol substrate
Synthesis and glycosidase inhibitory activity of new hexa- substituted C8-glycomimetics
Beilstein J. Org. Chem. 2005, 1, No. 12, doi:10.1186/1860-5397-1-12
- H2 (proS), H8 and H7 (proS) indicate a pseudo-equatorial position of protons H2 (proS) and H7 (proS). NOE measurements and finally Molecular Dynamic calculations using Insight II software (Biosym Technologies, San Diego, CA) allowed to deduce the structure of 11 (Figure 4). Prochiral H2 (proS) and H7
- protons (in bold) of the upper face of the C8 ring. Prochiral 1H are labelled pR or pS. X-ray structure of epoxide 7 (upper) and sulfate 9 (down) solved using SHELXS and anisotropically refined using SHELXL programs [38]. Reagents and conditions: (a) OsO4, NMO, tBuOH, rt; (b) TFA, H2O, rt. Reagents and
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