A new nitrone from C2 symmetric piperidine for the synthesis of hydroxylated indolizidinone

Brandi, Alberto; Cicchi, Stefano; Paschetta, Valentina; Pardo, Domingo Gomez; Cossy, Janine

doi:10.1016/s0040-4039(02)02336-5

Cited by 31 publications

(8 citation statements)

References 21 publications

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“…domino ring closure to the highly functionalized indolizidinone 111. [63] Summary and Outlook Hydroxylated pyrroline-N-oxides provide a general entry to the synthesis of polyhydroxylated pyrrolizidine and indolizidine alkaloids and their analogues. Their use appears attractive for many aspects that are a major topic in modern organic synthesis.…”

Section: Intramolecular Cycloaddition: Trans {Bridgehead-h 1-coh} Rel...mentioning

confidence: 99%

Stereocontrolled Cyclic Nitrone Cycloaddition Strategy for the Synthesis of Pyrrolizidine and Indolizidine Alkaloids

Brandi

Cardona

Cicchi

et al. 2009

Chemistry A European J

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236

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The synthesis of polyhydroxylated indolizidines and pyrrolizidines belonging to the class of iminosugars, endowed with a vast and assorted biological activity, can be achieved in a straightforward manner by a general strategy consisting of a highly stereoselective 1,3-dipolar cycloaddition of polyhydroxylated pyrroline-N-oxides followed by simple transformations of the isoxazolidine adducts. The strategy allows the complete control of the relative and absolute stereochemistry of the numerous stereogenic centers decorating these compounds.

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Section: Intramolecular Cycloaddition: Trans {Bridgehead-h 1-coh} Rel...mentioning

confidence: 99%

Stereocontrolled Cyclic Nitrone Cycloaddition Strategy for the Synthesis of Pyrrolizidine and Indolizidine Alkaloids

Brandi

Cardona

Cicchi

et al. 2009

Chemistry A European J

Self Cite

236

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“…1). It is important to note that simple a-hydrogen nitroxides that do not conform to this design are inherently unstable; for instance, oxidation of piperidine N-oxides with single substituents on C(2) or C(4) results in nitrones [40][41][42][43] .…”

Section: Resultsmentioning

confidence: 99%

“…We have shown that OTIPS and methyl groups on the radical backbone stabilize the isoindoline and iso-azaphenalene nitroxides. In contrast, the nitroxide derived by oxidation of quinone 22b decomposes rapidly as do other piperidine hydroxylamines upon oxidation [40][41][42][43] . The design principles outlined in the introduction were then evaluated, taking advantage of the power of computational studies of the nitroxides already demonstrated to be stable 12,49,50 .…”

Section: Resultsmentioning

confidence: 99%

Design concept for α-hydrogen-substituted nitroxides

et al. 2015

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Stable nitroxides (nitroxyl radicals) have many essential and unique applications in chemistry, biology and medicine. However, the factors influencing their stability are still under investigation, and this hinders the design and development of new nitroxides. Nitroxides with tertiary alkyl groups are generally stable but obviously highly encumbered. In contrast, a-hydrogen-substituted nitroxides are generally inherently unstable and rapidly decompose. Herein, a novel, concept for the design of stable cyclic a-hydrogen nitroxides is described, and a proof-of-concept in the form of the facile synthesis and characterization of two diverse series of stable a-hydrogen nitroxides is presented. The stability of these unique a-hydrogen nitroxides is attributed to a combination of steric and stereoelectronic effects by which disproportionation is kinetically precluded. These stabilizing effects are achieved by the use of a nitroxide co-planar substituent in the g-position of the backbone of the nitroxide. This premise is supported by a computational study, which provides insight into the disproportionation pathways of a-hydrogen nitroxides.

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“…The prolinol derivative 155, synthesized from commercially available (4R)-hydroxy-(2S)-hydroxymethylpyrrolidine, 103 was transformed into the C 2 -symmetric piperidine 156 that was then oxidized, using C-phenyl-Nbenzenesulfonyloxaziridine, to nitrone 157 in quantitative yield (Scheme 44). 104 This compound is extremely unstable and unsuitable for isolation in appreciable chemical purity and yield, but can afford in situ cycloaddition products with reactive dipolarophiles in high yields. It is worth mentioning that this instability is common to other sixmembered cyclic nitrones, which, in general, are known to undergo dimerization.…”

Section: Scheme 43mentioning

confidence: 99%

Enantiopure Cyclic Nitrones: A Useful Class of Building Blocks for Asymmetric Syntheses

Revuelta¹,

Cicchi²,

Goti³

et al. 2007

Synthesis

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A new nitrone from C2 symmetric piperidine for the synthesis of hydroxylated indolizidinone

Cited by 31 publications

References 21 publications

Stereocontrolled Cyclic Nitrone Cycloaddition Strategy for the Synthesis of Pyrrolizidine and Indolizidine Alkaloids

Stereocontrolled Cyclic Nitrone Cycloaddition Strategy for the Synthesis of Pyrrolizidine and Indolizidine Alkaloids

Design concept for α-hydrogen-substituted nitroxides

Enantiopure Cyclic Nitrones: A Useful Class of Building Blocks for Asymmetric Syntheses

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