25756-02-9Relevant 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 (2020/11/13)
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.
Iron-Catalyzed Radical Acyl-Azidation of Alkenes with Aldehydes: Synthesis of Unsymmetrical β-Azido Ketones
Ge, Liang,Li, Yajun,Bao, Hongli
, p. 256 - 260 (2019/01/10)
An iron-catalyzed acyl-azidation of alkenes under mild reaction conditions has been developed. Aromatic aldehydes or aliphatic aldehydes can be used as the acyl radical precursors; TMSN3 is used as the azido source; TBHP is the initiator. The s
Efficient and regioselective synthesis of 5-hydroxy-2-isoxazolines: Versatile synthons for isoxazoles, β-lactams, and γ-amino alcohols
Tang, Shibing,He, Jinmei,Sun, Yongquan,He, Liuer,She, Xuegong
supporting information; scheme or table, p. 1961 - 1966 (2010/06/20)
"Chemical Equation Presented" An efficient and highly regioselective protocol was developed for the preparation of 5-hydroxy2-isoxazolines, which have been proved to be versatile synthons for isoxazles, β-hydroxy oximes, and γ-amino alcohols. β-Lactams, commonly embedded in the skeletons of bioactive natural products, were also synthesized in two steps from β-hydroxy oximes, providing a new strategy for the synthesis of this kind of 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.
Generation of chromioenamines by reduction of O-acetyloximes with chromium(II) and their application
Takai,Katsura,Kunisada
, p. 1724 - 1725 (2007/10/03)
Chromioenamines can be generated by treatment of O-acetyloximes with chromium(II) via two steps of one-electron reduction and successive isomerization, and the species react with aldehydes to give γ-amino alcohols after reduction with LiA1H4.
NEW ASPECTS IN THE HYDROGENOLYTIC OPENING OF 2-ISOXAZOLINES
Auricchio, Sergio,Ricca, Aldo
, p. 3983 - 3986 (2007/10/02)
It has been observed that the hydrogenolytic opening of 2-isoxazolines depends on the substituents present in positions 3 and 5.The hydrogenolysis on 10percent Pd/C of 2-isoxazolines, substituted in position 3 with carbonyl or carboxyl groups and in posit
Electrochemical Reduction of Isoxazoles and Related Compounds
Surov, Igor,Lund, Henning
, p. 831 - 838 (2007/10/02)
Some isoxazoles, isoxazolines, and their quaternized derivatives have been investigated by polarography and preparative reduction.A reductive cleavage of the oxygen-nitrogen bond without reduction of the carbon-nitrogen double bond was possible in protic medium for the quaternized derivatives, whereas for the parent compounds this was possible only in aprotic medium.By this means, preferentially via quaternization, isoxazoles and isoxazolines may be transformed to β-diketones or β-hydroxyketones.Under suitable conditions, the quaternized isoxazoles and isoxazolines may be reduced to 1,3-aminoalcohols, the erythro:threo ratio of the products differing considerably.
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
cis- And trans-N-Nitroso-2,4-diphenylazetidines
Powell, Burwell F.,Reichenthal, Jules,Overberger, C. G.,Anselme, J.-P.
, p. 219 - 224 (2007/10/02)
The synthesis of cis- and trans-2,4-diphenylazetidines as well as that of their N-nitroso derivatives is described.The "abnormal" reduction of the N-nitrosamines gives a cis-trans mixture of the expected 1,2-diphenylcyclopropanes.However, no stereochemical correlations could be made owing to the base-induced isomerisation of the starting N-nitrosamines during the course of the reaction.
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.
