In Situ Generated Magnesium Cyanide as an Efficient Reagent for Nucleophilic Cyanation of Nitrosoalkenes and Parent Nitronates

Ushakov, Pavel Yu.; Tabolin, Andrey A.; Ioffe, Sema L.; Sukhorukov, Alexey Yu.

doi:10.1002/ejoc.201801761

Cited by 12 publications

(15 citation statements)

References 48 publications

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“…HPLC analysis: ee 58%, RT 4.5 min (major enantiomer), 3.5 min (minor enantiomer); column CHIRALPAK IA-3 (15 cm); solvent hexane/i-PrOH = 90:10; temperature 40 °C; flow rate 1 mL/min. NMR spectra are in agreement with published data …”

Section: Experimental Sectionsupporting

confidence: 91%

Construction of Saturated Oxazolo[3,2-b][1,2]oxazines via Tandem [3+2]-Cycloaddition/[1,3]-Rearrangement of Cyclic Nitronates and Ketenes

et al. 2021

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Reaction of six-membered cyclic nitronates with disubstituted ketenes affords hitherto unknown saturated oxazolo[3,2-b][1,2]oxazines possessing up to four contiguous stereogenic centers. The process involves a tandem of [3+2]-cycloaddition across the CO bond of ketene, followed by a spontaneous [1,3]-rearrangement of transient vinylidene-substituted bicyclic nitrosoacetals. DFT calculations of the mechanism suggest that the [1,3]-O,C-shift proceeds through a recyclization of a biradical intermediate formed by an unusually mild homolytic cleavage of the N–O bond. The resulting products can be utilized as precursors of other fused 1,2-oxazines derivatives, in particular 1,2-oxazino-1,2,4-triazin-3-ones.

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Section: Experimental Sectionsupporting

confidence: 91%

Construction of Saturated Oxazolo[3,2-b][1,2]oxazines via Tandem [3+2]-Cycloaddition/[1,3]-Rearrangement of Cyclic Nitronates and Ketenes

et al. 2021

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“…Unlike, nitroalkenes, nitrosoalkenes NSA (Scheme 5a) are unstable species that tend to polymerize and undergo side reactions. 26 Nevertheless, these intermediates have been successfully used in Michael additions with many nucleophiles, such as C-H active compounds, 27 organocopper compounds, 28 amines, 27c,29 phenols, 30 carboxylic acids, 30 thiols, 30b,31 dialkylphosphonates, 32 phosphine-borane complexes, 32 and cyanide 33 and azide anions, 34 among others 27c,35 (Scheme 5b). These reactions produce -substituted oximes that can be readily converted into the corresponding carbonyl compounds, amines, or hydroxylamines.…”

Section: Synpacts Syn Lettmentioning

confidence: 99%

Umpolung of Enamines: An Overview on Strategies and Synthons

Sukhorukov

2020

Synlett

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Umpolung strategies are of considerable interest to organic chemists because they provide alternative synthetic routes to those imposed by the natural polarity of classical synthons. Reverse-polarity reactions of aldehydes, α,β-unsaturated carbonyl compounds, and imines are deeply embedded in the methodology of organic synthesis. In recent years, umpolung of enols and enamines has received much attention as a novel strategy to access α-substituted ketones. Here, state-of-the-art approaches to umpolung of enamine reactivity are discussed, with a particular focus on recent developments in this field from the author’s research group.1 Introduction2 Approaches toward Umpolung of Enamines3 Umpolung of Enamines through Single-Electron Oxidation4 Azadienes as Synthetic Equivalents of Enamine Umpolung Synthons5 Enamines Possessing a Leaving Group at the Nitrogen Atom6 Enamines Possessing a Directing Group at the Nitrogen Atom7 Summary and Outlook

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“…Nucleophiles such as cyanide and azide anions, the H‐forms of which are dangerous to handle, were reacted with N , N ‐bis(siloxy)enamines 13 and 15 in the form of their TMS derivatives or magnesium salts generated in situ (Scheme ). In the case of cyanide, initially formed α‐cyanoximes 126 cyclize into the corresponding 5‐aminoizoxazoles 127 …”

Section: Nitrones and Nitronates As α‐C‐electrophilic Synthonsmentioning

confidence: 99%