13286-60-7Relevant academic research and scientific papers
Highly Diastereoselective Reactions of Isoxazolidine-4,5-diols with Grignard Reagents: A New Approach to anti, syn -γ-Amino-α,β-diols
?urina, Luká?,Malatinsky, Tomá?,Moncol, Ján,Záborsky, Ondrej,Fischer, Róbert
, p. 688 - 698 (2021)
An investigation of the reaction of 3,4- trans -isoxazolidine-4,5-diols with Grignard reagents is described for the first time. Their resemblance to five-membered cyclic hemiacetals allows them to react as α-hydroxy-β-(hydroxyamino)aldehydes in a highly stereoselective manner, providing anti, syn -γ-(hydroxyamino)-α,β-diols in moderate yields and with good to excellent syn -diastereoselectivities, which can be improved by the addition of anhydrous cerium chloride. The obtained (hydroxyamino-)diols serve as suitable precursors of anti, syn -γ-amino-α,β-diols that represent valuable scaffolds for the synthesis of various biologically active compounds.
Asymmetric reduction of racemic 2-isoxazolines
Tokizane, Masashi,Sato, Kaori,Ohta, Tetsuo,Ito, Yoshihiko
scheme or table, p. 2519 - 2528 (2009/04/04)
The kinetic resolution of racemic 2-isoxazolines was carried out by asymmetric reduction using borane with 1,2-amino alcohols as a chiral source. Using excess BH3-THF in the presence of (-)-norephedrine, optically active 1,3-amino alcohol derivatives were obtained with good ee but in lower yield, while the optically active substrates 2-isoxazolines were recovered with modest ee. The asymmetric reduction using 2.0 equiv of BH3-SMe2 was investigated as an alternative strategy for the synthesis of optically active products. After reduction, treatment of the resulting mixture with Et3N was successful in providing optically active isoxazolidine derivatives in good yields and with good ee. The choice of chiral source was also shown to have a significant effect. In particular, the use of (S)-α,α-diphenyl-2-pyrrolidinemethanol reversed the enantioselectivity of the recovered substrates.
Stereoselective Preparation of Acyclic syn-β-Amino Alcohols from β-Hydroxy Ketones via the Corresponding O-Benzyl Oximes
Narasaka, Koichi,Ukaji, Yutaka,Yamazaki, Shigeru
, p. 525 - 534 (2007/10/02)
Reduction of β-hydroxy ketone O-benzyl oximes with lithium aluminum hydride in the presence of sodium or potassium methoxide afforded the corresponding syn-β-amino alcohols in highly stereoselective manner.A lythraceae alkaloid, lasubine II, was synthesiz
Synthesis via Isoxazolines, 5. - 1,3-Asymmetric Induction in the reduction of 3,5-Disubstituted 2-Isoxazolines; Diastereoselective Synthesis and Configurational Assignment of γ-Amino Alcohols
Jaeger, Volker,Buss, Volker
, p. 101 - 121 (2007/10/02)
The cycloaddition of nitrile oxides to alkenes, followed by reduction of the ensuing 2-isoxazolines 3, yields γ-amino alcohols 4 in a regioselective manner.The stereoselectivity of the reduction step is examined; it is highest with LiAlH4 as the reducing agent. 1,3-Asymmetric induction by isoxazoline ring substituents leads to β-4:α-4 ratios of ca. 85:15 for 5-methyl and ca. 95:5 for 5-phenyl. (CH3)2S-BH3, less selectively, furnishes 60:40, Na-Hg and Na/ethanol reduction give rise to 40:60 diastereomer mixtures.From these, two amino alcohols of the α-series are isolated. 3a is reduced by NaBH3CN to give cis/trans-isoxazolines 11. - The relative configurations of β- and α-4 and, consequently, the steric course of these reductions, are established by 1H- and 13C-NMR studies of 4 as well as of cyclic derivatives (azetidine 7, tetrahydro-1,3-oxazine 10).In addition, conformations of the free amino alcohols 4 are suggested on the basis of 13C-NMR data.
