- Oxazaborolidine-mediated asymmetric reduction of 1,2-diaryl-2- benzyloxyiminoethanones and 1,2-diarylethanediones
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Highly enantioselective reduction of 1,2-diaryl-2- benzyloxyiminoethanones and 1,2-diarylethanediones was conducted using oxazaborolidine derived from L-threonine and borane complexes to give β- imino alcohols and 1,2-diaryl-1,2-ethanediols in high enantiomeric purity. Subsequent reduction of the imino functionality of the former products afforded either syn- or anti-2-amino-1,2-diarylethanols in high enantiomeric purity by choosing appropriate reduction methods.
- Shimizu, Makoto,Tsukamoto, Keiko,Matsutani, Takayuki,Fujisawa, Tamotsu
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p. 10265 - 10274
(2007/10/03)
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- Reactions of α-Hydroxy Carbonyl Compounds with Azodicarboxylates and Triphenylphosphine: Synthesis of α-N-Hydroxy Amino Acid Derivatives
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Reaction of aliphatic α-hydroxy esters with azodicarboxylates and triphenylphosphine in the presence of either CbzNHOCH2Ph or trOCNHOCH2Ph provides a direct route to protected α-N-hydroxy amino acids.Similar reactions with aromatic α-hydroxy carbonyl compounds and derivatives result in predominate oxidation to the corresponding α-oxo carbonyl derivatives.
- Kolasa, Teodozyj,Miller, Marvin J.
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p. 4978 - 4984
(2007/10/02)
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- Methylthiomethyl Nitrones Derived from the Oximes of Benzil: Preparation, Thermolysis, and Photolysis
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Reaction between benzil E-monoxime, N-chlorosuccinimide, dimethyl sulphide, and triethylamine gave a mixture of the isomeric C-benzoyl-C-phenyl-N-methylthiomethyl nitrones (2) and (3).The isomers were thermally and photochemically interconverted, and longer heating afforded benzoin, 2-methylthio-4,5-diphenyl-1,3-oxazole, 4,5-diphenyl-1,3-oxazole, and benzil O-methylthiomethyl-Z-oxime as products.Photolysis gave the first three products as well as dimethyl disulphide.Mechanisms are suggested for these reactions.Attempted alkylation of benzil E- and Z-monoximes with methylthiomethyl chloride gave methylthiomethyl benzoate, phenyl cyanide, and benzoic acid, for which a fragmentation mechanism is proposed.Benzoin E-oxime underwent Beckmann fragmentation when formation of nitrone was attempted.
- Ooi, Ngan Sim,Wilson, David A.
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p. 4501 - 4512
(2007/10/02)
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