Kinetic Resolutions by Means of Cycloaddition Reactions

Cardona, Francesca; Goti, Andrea; Brandi, Alberto

doi:10.1002/1099-0690(200108)2001:16<2999::aid-ejoc2999>3.0.co;2-4

Cited by 35 publications

(10 citation statements)

References 34 publications

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“…Modern chemistry has benefited from the synthetic power and versatility of dipolar cycloaddition and cyclization reactions, [1][2][3][4] which have enabled far-reaching advances in many pursuits, from the preparation of unnatural β-amino acids, [5] to the kinetic resolution of stereoisomers, [6] to the functionalization of carbon nanotubes. [7] Alkyne-azide 1,3-dipolar cycloadditions are an especially practical subclass of reactions, given that molecules comprising terminal alkyne [8][9][10] and azide [11] functionalities are synthetically accessible and often commercially available.…”

Section: Introductionmentioning

confidence: 99%

Methylation of Ylidene‐Triazenes: Insight and Guidance for 1,3‐Dipolar Cycloaddition Reactions

et al. 2010

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Reaction of 1,3-dimesitylimidazolylidene (1) with p-functionalized phenyl azides 2 (a: H, b: OCH 3 , c: NO 2 ) afforded the respective imidazolylidene-triazenes 3 in good yields (65-99 %). Subsequent treatment with methyl iodide produced the corresponding methylated products 4 in near-quantitative yields (99 %). Analysis by NOESY 1D NMR spectroscopy and single-crystal X-ray diffraction revealed that the methylation reaction was regioselective and occurred at the nitrogen atom most distal from the heterocycle. Consistent with the formation of ionic salts, the 1 H NMR signals for the imidazole protons in 4 were shifted Ͼ 0.5 ppm downfield compared to 1, indicating the accumulation of positive charge.

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Section: Introductionmentioning

confidence: 99%

Methylation of Ylidene‐Triazenes: Insight and Guidance for 1,3‐Dipolar Cycloaddition Reactions

et al. 2010

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“…Brandi and co-workers used triacetyl-d-glucal (S)-24 a and triacetyl-l-rhamnal (R)-24 b as quasiracemates to resolve nitrones 23 with modest selectivities. [25] In contrast, high selectivities were observed by Fox and co-workers in resolution of cyclopropene carboxylic acid chlorides 26 with quasienantiomeric oxazolidinones derived from d-phenylalanine (S)-27 a and l-tyrosine (R)-27 b. [26] Davies and coworkers resolved 3-alkylcycopentene-1-carboxylate esters 29 by 1,4-addition reactions with quasienantiomeric derivatives (S)-30 a and (R)-30 b of phenethyl amine ( Figure 6).…”

Section: Quasienantiomers As Tools For Enantiomer Separationmentioning

confidence: 99%

Quasienantiomers and Quasiracemates: New Tools for Identification, Analysis, Separation, and Synthesis of Enantiomers

Zhang

Curran

2005

Chemistry A European J

105

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The old adage "never mix pure organic compounds" holds in spades for enantiomers. After going to all the trouble to make enantiopure molecules, who in their right mind would ever mix them to make a racemate? Quasienantiomers are almost enantiomers, but not quite. Yet unlike enantiomers, the interest is not so much in separating them but in mixing them to make quasiracemates. This backwards thinking opens new possibilities for identification, analysis, separation and synthesis of enantiomers. A short history is provided, the terms are defined and illustrated, and recent applications of quasienantiomers, quasiracemates and related species are reviewed.

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“…Kinetic resolution (Kagan and Fiaud, 1988, Vedejs and Jure, 2005, Pellissier, 2011) is one of the commonly used strategies to obtain the optically active compounds from racemic starting materials, which was recently also employed in cycloaddition reactions (Cardona et al., 2001, Yu et al., 2010, Takayama et al., 2013, Xu et al., 2016, Yuan et al., 2018). As part of our ongoing research interest in asymmetric 1,3-dipolar cycloaddition (Wang et al., 2008, Wang et al., 2012, He et al., 2013, Li et al., 2014), we considered employing kinetic resolution strategy to develop a new cycloaddition process with readily accessible racemic alkylidene norcamphors as dipolarophiles (Figure 1C).…”

Section: Introductionmentioning

confidence: 99%

Kinetic Resolution of Alkylidene Norcamphors via a Ligand-Controlled Umpolung-Type 1,3-Dipolar Cycloaddition

et al. 2019

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SummaryDevelopment of a general catalytic and highly efficient method utilizing readily available precursors for the regio- and stereoselective construction of bioactive natural-product-inspired spiro architectures remains a formidable challenge in chemical research. Transition metal-catalyzed asymmetric 1,3-dipolar cycloaddition of azomethine ylides produces numerous N-heterocycles, but reaction control with the regioselectivity opposite to the conventional fashion has rarely been demonstrated. Herein, we report a unique ligand-controlled Cu(I)-catalyzed umpolung-type 1,3-dipolar cycloaddition of azomethine ylide to realize efficient kinetic resolution of racemic alkylidene norcamphors with the concomitant construction of previously inaccessible spiro N-heterocycles with high levels of regio- and stereoselectivity. The success of this methodology relies on the strategy of kinetic resolution, and the serendipitous discovery of a unique ligand-enabled regiospecific cycloaddition, which not only provides evidence for the existence of the minor zwitterionic resonance form in metallated azomethine ylide but also diversifies the existing chemistry of azomethine ylide-involved 1,3-dipolar cycloadditions with rare polarity inversion.

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Kinetic Resolutions by Means of Cycloaddition Reactions

Cited by 35 publications

References 34 publications

Methylation of Ylidene‐Triazenes: Insight and Guidance for 1,3‐Dipolar Cycloaddition Reactions

Methylation of Ylidene‐Triazenes: Insight and Guidance for 1,3‐Dipolar Cycloaddition Reactions

Quasienantiomers and Quasiracemates: New Tools for Identification, Analysis, Separation, and Synthesis of Enantiomers

Kinetic Resolution of Alkylidene Norcamphors via a Ligand-Controlled Umpolung-Type 1,3-Dipolar Cycloaddition

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