The quest for observation and isolation of oxyallyl derivatives

Regnier, Vianney; Martín, David

doi:10.1039/c5qo00230c

Cited by 16 publications

(3 citation statements)

References 81 publications

(50 reference statements)

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“…As first mentioned by Hoffmann in 1968, oxyallyl derivatives have been postulated as intermediates in an umber of rearrangements and cycloaddition reactions [30] such as the Favorskii rearrangement [31] and the photochemical rearrangemento f cyclohexadienones. [32] Although the parent oxyallyl compounds are too elusive to isolate, [33] an umber of oxyallyl derivatives have been synthesized by involvingt ransition-metal complexes [34] and electron donors such as NHCs. [22b, 35] However, transiento xyallylr adical cations have been observed by EPR spectroscopy in ag lassy matrix at 77 Ka nd by mass spectrometry.…”

Section: Oxyallyl Radicalsmentioning

confidence: 99%

Stable Organic Radicals Derived from N‐Heterocyclic Carbenes

Kim

Lee

2018

Chemistry A European J

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Over the past decade, numerous stable organic and main-group radicals have been synthesized from N-heterocyclic carbenes (NHCs). The structure of NHCs, in particular, offers electronic stabilization that helps to delocalize the unpaired electron over the molecule. In addition, the sterically bulky substituents of NHCs protect the radical center to prevent detrimental reactions such as dimerization. These advantages enable the straightforward synthesis and characterization of various interesting organic radicals starting from NHCs, which are, these days, widely available. NHCs have enabled the structural characterization of various organic radicals over the past decade, including α-carbonyl, propargyl, oxyallyl, and triazenyl radicals as notable examples. This minireview summarizes the advances in this field, mainly focusing on the preparation and stability as well as the properties and applications of NHC-derived organic radicals.

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Section: Oxyallyl Radicalsmentioning

confidence: 99%

Stable Organic Radicals Derived from N‐Heterocyclic Carbenes

Kim

Lee

2018

Chemistry A European J

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“…Intrigued by these resultsw ew ere interestedi nf urthere xplorationo f small ring systems in this strain-induced reactionb ut, although cyclobutanone derivatives are known to be relativelys table, cyclopropanones often decompose instantly at room temperature. [15] Kinetically unstablet oh eat, light and moisture, their most common decomposition pathways involve either polymerization,d ecarbonylation to alkenes, formation of hydrates, hemiketals, and hemiaminals/iminium ions, nucleophilic ringopeninga si nt he Favorskii rearrangement or,a ss een in Scheme 1a,s ome combination of these processes. [16] We considered that 1-siloxycyclopropenes which are availablef rom vinyldiazo compounds by dinitrogen extrusion [9] would be suitable precursors to cyclopropanones and their subsequentr ing opening.…”

Section: Introductionmentioning

confidence: 99%

Strain‐Induced Nucleophilic Ring Opening of Donor–Acceptor Cyclopropenes for Synthesis of Monosubstituted Succinic Acid Derivatives

Marichev

Wang

Greco

et al. 2020

Chemistry A European J

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1,2,3-Trisubstituted donor-acceptor cyclopropenes (DACPs) generatedi ns itu from enoldiazo compounds react with nucleophilest of orm a-substituted succinic acid derivatives in high yields. Initial dirhodium(II)c arboxylate catalysis rapidly converts enoldiazo-acetates or-acetamides to DACPs that undergo catalyst-free Favorskii ring openingw ith amines, and also with anilines,a lcohols, and thiols, when facilitated by catalytic amounts of 4-dimethylaminopyridine (DMAP). This methodology providese asy access to mixed esters and amides of monosubstituted succinic acids, including derivatives of naturallyo ccurring compounds.I ta lso affords dihydrazide, dihydroxamic acid, and diamide derivatives, as well as a-substituted tetrahydropyridazine-3,6diones in high yields. Attempts to generate optically enriched DACPs were not successful because their populations having the R and S configurations formedw ithachiral dirhodiumcatalystare quite similar, and the loss of enantiocontrol likely originates from the DACP ring forming step which is reversible with its intermediate metal carbene. Scheme1.Nucleophilic retro-Claisen and Favorskii-type ring opening of strained ring systems.

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“…Oxyallyl species A (see Scheme 1), [1,2] also called oxyallyl cations,h ave been postulated as reactive intermediates in numerous reactions, [3,4] including 1,3-dipolar cycloadditions, [5,6] and in in vivo biosyntheses. [7] They are non-disjoint non-KekulØ diradicaloids with singlet ground states.…”

Section: Introductionmentioning

confidence: 99%

Air‐Stable Oxyallyl Patterns and a Switchable N‐Heterocyclic Carbene

et al. 2020

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Oxyallyl derivatives are typically elusive compounds. Even recently reported “stabilized” 1,3‐diaminooxyallyl species are still highly reactive and have short lifetimes at room temperature. Herein, we report the synthesis and preliminary study of mesoionic pyrimidine derivatives that feature 1,3‐bis(dimethylamino)oxyallyl patterns with an unprecedented level of stabilization. The latter are not only insensitive towards air and moisture, but they are also compatible with the formation of an ancillary stable N‐heterocyclic carbene moiety. As the oxyallyl pattern is proton‐responsive, it allows the reversible switching of the electronic properties of the carbene, as a ligand.

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The quest for observation and isolation of oxyallyl derivatives

Abstract: International audienc

Cited by 16 publications

References 81 publications

Stable Organic Radicals Derived from N‐Heterocyclic Carbenes

Stable Organic Radicals Derived from N‐Heterocyclic Carbenes

Strain‐Induced Nucleophilic Ring Opening of Donor–Acceptor Cyclopropenes for Synthesis of Monosubstituted Succinic Acid Derivatives

Air‐Stable Oxyallyl Patterns and a Switchable N‐Heterocyclic Carbene

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