- New chiral bis(oxazoline) Rh(I)-, Ir(I)- and Ru(II)-complexes for asymmetric transfer hydrogenations of ketones
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Chiral bis(oxazoline)-based Rh(I)-, Ir(I)- and Ru(II)-complexes have been prepared and used for asymmetric transfer hydrogenation of prochiral ketones. The presence of a free hydroxyl group on the ligand is necessary for high enantioselectivity. With acetophenone, up to 50% conversion and 89% ee were achieved.
- Debono, Nathalie,Besson, Michèle,Pinel, Catherine,Djakovitch, Laurent
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- Enantioselective Total Synthesis of Cannogenol-3-O-α- l -rhamnoside via Sequential Cu(II)-Catalyzed Michael Addition/Intramolecular Aldol Cyclization Reactions
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A concise and scalable enantioselective total synthesis of the natural cardenolides cannogenol and cannogenol-3-O-α-l-rhamnoside has been achieved in 18 linear steps. The synthesis features a Cu(II)-catalyzed enantioselective and diastereoselective Michae
- Bhattarai, Bijay,Nagorny, Pavel
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supporting information
p. 154 - 157
(2018/01/17)
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- New chiral oxazoline based-rhodium(I) catalysts: Synthesis, characterisation, heterogeneisation and applications
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New chiral oxazoline-based rhodium(I) homogeneous and heterogeneous catalysts have been prepared and fully characterised through 1H and 13C NMR, CP-MAS NMR and XPS. The method used for anchoring the catalyst onto silica was found par
- Debono, Nathalie,Djakovitch, Laurent,Pinel, Catherine
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p. 741 - 747
(2007/10/03)
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- Heterogeneous asymmetric nitro-Mannich reaction using a bis(oxazoline) ligand grafted on mesoporous silica
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A chiral bis(oxazoline) ligand was immobilized on mesoporous silica (SBA-15) and examined in an asymmetric heterogeneous nitro-Mannich reaction. Depending upon the size of the alkyl chain in the nitroalkane substrates, enantioselectivities comparable to and higher diastereoselectivities (syn/anti ratio) than those obtained from homogeneous reactions were observed. In the case of the long chain substituted nitroalkane substrate (nitrohexane), the best selectivities (diastereoselectivity: syn/anti = 98/2, and enantioselectivity: 93% and 82% ee's for syn- and anti-isomers, respectively), were observed. Recycling of the catalyst in subsequent reactions was carried out and gradually diminishing levels of both diastereo and enantioselectivities were observed after each recycle.
- Lee, Anna,Kim, Woosung,Lee, Jinwoo,Hyeon, Taeghwan,Kim, B. Moon
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p. 2595 - 2598
(2007/10/03)
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- Asymmetric copper complex and cyclopropanation reaction using the same
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There are disclosed asymmetric copper complex comprising, as components, (a) an optically active bisoxazoline compound of formula (1): wherein R1 and R2 are different and each represent a hydrogen atom, an alkyl group, a cycloalkyl group, or a phenyl or aralkyl group which may be substituted, R3 and R4 each represent a hydrogen atom, an alkyl group, a cycloalkyl group, or a phenyl or aralkyl group which may be substituted, or R3 and R4 may be bonded to each other to form a C3-5 cyclic alkylene group, R5 represents a hydrogen atom or a C1-6 alkyl group, or the two R5 groups may be bonded to each other to represent a C3-5 cyclic alkylene group, (b) a monovalent or divalent copper compound, and (c) a strong acid or a Lewis acid or a mixture thereof, and a process for producing an optically active cyclopropanecarboxylate using the same.
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- Spectroscopic studies on complexes of magnesium (II) with C2-chiral bis-oxazolines
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The configurations of chloro, ethyl and bis-complexes of magnesium with C2-chiral bis-oxazolines such as 2,2′-methylenebis[(4S)-4-iso-propyl-2-oxazoline] (MBIO). 2,2′-methylenebis[(4S)-4-tert-butyl-2-oxazoline] (MBTO) and 2,2′-methylenebis[(4S)-4-phenyl-2-oxazoline] (MBPO) have been investigated on the basis of spectroscopic studies. The IR and NMR (1H, 13C) data suggested that the bis-oxazoline ligands coordinated magnesium (II) through both the nitrogen atoms. The molecular weight determination in nitrobenzene indicated the dimeric nature of chloro and ethylmagnesium complexes whereas bis-magnesium complexes were found to be monomeric.
- Singh
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p. 1713 - 1717
(2007/10/03)
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