- Enantioselective one-pot catalytic synthesis of 4,5-epoxy-3-alkanols and 1-Phenyl-2,3-epoxy-1-alkanols from α,β-unsaturated aldehydes
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Conformationally restricted perhydrobenzoxazines have been demonstrated to be good chiral ligands for one-pot asymmetric ethylation/epoxidation, and the unprecedented arylation/epoxidation of trisubstituted α,β-unsaturated aldehydes. The scope of the reaction has been studied and a wide set of substrates with allylic strain of different nature has been explored, obtaining good or total diastereoselectivities in all cases. The enantiocontrol was good or high for the ethylation/epoxidation reaction, whereas it remained at moderate or good levels for the arylation/epoxidation. The reaction is general for trisubstituted enals, and alkylic and aromatic substituents are tolerated at both the α- and β-position of the unsaturated aldehyde; however, disubstituted enals remain challenging substrates. When the one-pot and two-pot protocols were compared, no significant differences concerning the stereocontrol were found, so the advantages of the one-pot procedure are clear. Copyright
- Infante, Rebeca,Hernandez, Yulan,Nieto, Javier,Andres, Celia
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supporting information
p. 4863 - 4869
(2013/08/23)
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- PaaSicats: Powerful catalysts for asymmetric epoxidation of enones. Novel syntheses of α-arylpropanoic acids including (S)-fenoprofen
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Application of the recently developed silica-adsorbed polyleucine catalysts to the enantioselective epoxidation of two enones is reported. Treatment of these epoxides with trimethylaluminium in moist dichloromethane generates the α-hydroxy-β-methylketones, with inversion of configuration. Diastereoselective reduction of the ketone moiety followed by oxidative cleavage generates α-arylpropanoic acids.
- Carde, Lydia,Davies, Huw,Geller, Thomas P.,Roberts, Stanley M.
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p. 5421 - 5424
(2007/10/03)
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- Synthesis of novel C2-symmetric ligands based on (R,R)- and (S,S)- diphenyl-1,3-propanediol
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A range of novel C2-symmetric dioxygen and dinitrogen ligands can readily be obtained through the interconversion of the parent 1,3-diphenyl- 1,3-propanediol enantiomers which are, in turn, accessed in good yields via a Sharpless asymmetric epoxidative resolution.
- Roos, Gregory H. P.,Donovan, A. Richard
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p. 991 - 1000
(2007/10/03)
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- Asymmetric allylic substitution reaction with nitrogen and oxygen nucleophiles using monodentate chiral phosphine, 9-PBN
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Asymmetric allylic substitution reactions between 1,3-diphenyl-2-propenyl acetate and various hetero nucleophiles were efficiently carried out using the catalysts derived from the monodentate phosphine ligands, (1R, 2S, 5R, 6S)-2,6-dimethyl-9-phenyl-9-phosphabicyclo[3.3.1] nonane and its enantiomer ((-)- and (+)-9-PBNs), and palladium (0).
- Hamada, Yasumasa,Seto, Noriko,Takayanagi, Yoshie,Nakano, Takeshi,Hara, Osamu
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p. 7791 - 7794
(2007/10/03)
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