Stereochemistry of cycloaddition of (S)-N-(1-phenylethyl)-C-diethoxyphosphorylated nitrone with vinyl acetate. Studies on mutarotation of 3-(O,O-diethylphosphoryl)-5-hydroxyisoxazolidines

Piotrowska, Dorota G.

doi:10.1016/j.tetasy.2008.01.009

Cited by 16 publications

(8 citation statements)

References 52 publications

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“…Although it is difficult to discriminate between the conformers and diastereomers of the isoxazoline associated with nitrogen inversion in 1 H NMR analysis, , our findings clearly demonstrated that 6da and 7da are interconvertible. Such interconversion has also been reported in the similar 5-hydroxyisoxazolidines − prepared by the addition of the hydroxylamine to α,β-unsaturated carbonyl compounds . On the other hand, when we examined the reaction with isolable π-conjugated ( Z )-nitrones ( 1e – h ), which structurally resemble C -CN nitrones (Figures S6–S9), the corresponding (3 + 2) adducts were not detected (Table , entries 5–8).…”

Section: Resultssupporting

confidence: 77%

Dynamics in Catalytic Asymmetric Diastereoconvergent (3 + 2) Cycloadditions with Isomerizable Nitrones and α-Keto Ester Enolates

et al. 2021

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Reaction design in asymmetric catalysis has traditionally been predicated on a structurally robust scaffold in both substrates and catalysts, to reduce the number of possible diastereomeric transition states. Herein, we present the stereochemical dynamics in the Ni(II)-catalyzed diastereoconvergent (3 + 2) cycloadditions of isomerizable nitrile-conjugated nitrones with α-keto ester enolates. Even in the presence of multiple equilibrating species, the catalytic protocol displays a wide substrate scope to access a range of CN-containing building blocks bearing adjacent stereocenters with high enantio-and diastereoselectivities. Our computational investigations suggest that the enantioselectivity is governed in the deprotonation process to form (Z)-Ni-enolates, while the unique syn addition is mainly controlled by weak noncovalent bonding interactions between the nitrone and ligand.

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Section: Resultssupporting

confidence: 77%

Dynamics in Catalytic Asymmetric Diastereoconvergent (3 + 2) Cycloadditions with Isomerizable Nitrones and α-Keto Ester Enolates

et al. 2021

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“…Because all of them depend on the dihedral angle in a Karplus‐type relationship, these differences are attributable to different conformations of the ring 20. Indeed, molecular mechanics models indicate that in 65 the 1,2‐oxaphospholane ring preferentially adopts an envelope E 4 conformation with phase angle P = 52°, whereas 66 shows a preference for an E 3 ( P = 204°) 37c,38b,39…”

Section: Resultsmentioning

confidence: 99%

Fragmentation of Carbohydrate Anomeric Alkoxyl Radicals: Synthesis of Chiral Polyhydroxylated β‐Iodo‐ and Alkenylorganophosphorus(V) Compounds

2014

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A direct approach to β‐iodophosphonates and β‐iodophosphine oxides from 2,3‐dideoxy‐3‐phosphoryl carbohydrate derivatives has been achieved by using the anomeric alkoxyl radical 1,2‐fragmentation protocol. The reaction has been conducted on carbohydrate derivatives under mild conditions with (diacetoxyiodo)benzene and molecular iodine. Subsequent dehydroiodination afforded the corresponding vinylphosphonates and vinylphosphine oxides.

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“…Recently, we succeeded in the synthesis of N-substituted Cphosphorylated nitrone 8 [14] and its application in the 1,3-dipolar cycloaddition with vinyl acetate was described [15]. Furthermore, the usefulness of C5-acetoxyisoxazolidines 9 as precursors in the synthesis of isoxazolidine nucleoside analogues 10 has recently been demonstrated (Scheme 1) [15,16].…”

Section: Introductionmentioning

confidence: 99%

Design, synthesis, antiviral and cytostatic evaluation of novel isoxazolidine nucleotide analogues with a 1,2,3-triazole linker

Piotrowska

Balzarini

Głowacka

2012

European Journal of Medicinal Chemistry

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Azidation (TMSN(3), SnCl(4)) of a 9:1 mixture of trans- and cis-5-acetoxy-2-methylisoxazolidin-3-yl-3-phosphonates at the anomeric carbon atom led to the formation of the equimolar mixture of cis- and trans-5-azido-2-methylisoxazolidin-3-yl-3-phosphonates, which were efficiently separated. The 1,3-dipolar cycloaddition of pure trans- and cis-5-azidoisoxazolidin-3-yl-3-phosphonates with selected alkynes gave the respective nucleoside mimetics containing a 1,2,3-triazole linker. The (1,2,3-triazolyl)isoxazolidine phosphonates obtained herein were evaluated in vitro for activity against a variety of DNA and RNA viruses. None of the compounds were endowed with antiviral activity at subtoxic concentrations. Compounds 15f-j and 16f-j were cytostatic in the higher micromolar range.

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Stereochemistry of cycloaddition of (S)-N-(1-phenylethyl)-C-diethoxyphosphorylated nitrone with vinyl acetate. Studies on mutarotation of 3-(O,O-diethylphosphoryl)-5-hydroxyisoxazolidines

Cited by 16 publications

References 52 publications

Dynamics in Catalytic Asymmetric Diastereoconvergent (3 + 2) Cycloadditions with Isomerizable Nitrones and α-Keto Ester Enolates

Dynamics in Catalytic Asymmetric Diastereoconvergent (3 + 2) Cycloadditions with Isomerizable Nitrones and α-Keto Ester Enolates

Fragmentation of Carbohydrate Anomeric Alkoxyl Radicals: Synthesis of Chiral Polyhydroxylated β‐Iodo‐ and Alkenylorganophosphorus(V) Compounds

Design, synthesis, antiviral and cytostatic evaluation of novel isoxazolidine nucleotide analogues with a 1,2,3-triazole linker

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