1H-Benzazirines. Intermediates in the ring contraction of iminocyclohexadienylidenes and arylnitrenes

Thetaz, Celestin; Wentrup, Curt

doi:10.1021/ja00421a034

Cited by 60 publications

(41 citation statements)

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“…An arene aziridine is also observed (ion c), which arises from a second loss of CO [544][545][546] . The ions b and c are also observed in the gas-phase pyrolysis of isatin 547 . In a general manner, the mass spectra of 3-substituted isatins show a sequential loss of neutral molecules 548 (Scheme 135).…”

Section: Mass Spectrometrymentioning

confidence: 89%

The chemistry of isatins: a review from 1975 to 1999

Silva¹,

Garden²,

Pinto³

2001

J. Braz. Chem. Soc.

858

447

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Isatinas (1H-indol-2,3-diona) são compostos de grande versatilidade sintética, podendo ser utilizados na obtenção de diversos sistemas heterociclos, como derivados indólicos e quinolínicos, o que as tornam importantes matérias-primas na síntese de fármacos. Isatinas também têm sido detectadas em tecidos de mamíferos, o que tem despertado o interesse em seu estudo como moduladores em diversos processos bioquímicos. Os avanços na aplicação de isatinas em síntese orgânica, bem como na compreensão de seus efeitos biológicos e farmacológicos nos últimos vinte e cinco anos encontram-se relatados nesta revisão e seus respectivos materiais suplementares.Isatins (1H-indole-2,3-dione) are synthetically versatile substrates, where they can be used for the synthesis of a large variety of heterocyclic compounds, such as indoles and quinolines, and as raw material for drug synthesis. Isatins have also been found in mammalian tissue and their function as a modulator of biochemical processes has been the subject of several discussions. The advances in the use of isatins for organic synthesis during the last twenty-five years, as well as a survey of its biological and pharmacological properties are reported in this review and in the accompanying supplementary information.

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Section: Mass Spectrometrymentioning

confidence: 89%

The chemistry of isatins: a review from 1975 to 1999

Silva¹,

Garden²,

Pinto³

2001

J. Braz. Chem. Soc.

858

447

View full text Add to dashboard Cite

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“…Labelling experiments have demonstrated that, in fact, all ring carbon atoms in cyanocyclopentadiene become completely scrambled due to these rapid sigmatropic shifts of H and CN. [41] Napthyl Azides ] Naphthylnitrenes A mixture of 2-and 3-cyanoindenes 17 and 16 is obtained on FVT of 1-and 2-naphthyl azides 8 and 22 as well as the triazoles and tetrazoles 10, 11, 21, and 24 at 340-4008C (Scheme 2). The triazoles and tetrazoles have been shown to be precursors of quinolyl-and isoquinolylcarbenes, which rearrange to the 1-and 2-naphthylnitrenes via ring expansion to cyclic carbodiimides 12 and 19.…”

Section: Phenyl Azide ] Phenylnitrene ] Cyanocyclopentadienementioning

confidence: 99%

Chemical Activation in Azide and Nitrene Chemistry: Methyl Azide, Phenyl Azide, Naphthyl Azides, Pyridyl Azides, Benzotriazoles, and Triazolopyridines

Wentrup¹

2013

Aust. J. Chem.

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Chemical activation (the formation of 'hot' molecules due to chemical reactions) is ubiquitous in flash vacuum thermolysis (FVT) reactions, and awareness of this phenomenon is indispensable when designing synthetically useful gas-phase reactions. Chemical activation is particularly prevalent in azide chemistry because the interesting singlet nitrenes are high-energy intermediates, and their reactions are highly exothermic. Consequently, chemical activation is observed in the isomerization of methylnitrene CH 3 N to methylenimine (methanimine) CH 2 ¼NH, facilitating the elimination of hydrogen to form HCN or HNC. Rearrangements of phenylnitrene, 1-and 2-naphthylnitrenes, and 2-, 3-and 4-pyridylnitrenes afford cyanocyclopentadiene, 3-and 2-cyanoindenes, and 2-and 3-cyanopyrroles, all showing the effects of chemical activation by undergoing facile interconversion of isomers. Chemical activation can often be reduced or removed entirely by increasing the pressure, thereby promoting collisional deactivation. Larger molecules having more degrees of freedom are better able to dissipate excess energy; therefore the effects of chemical activation are less pronounced or completely absent in the formation of 3-cyanoindole and 1-cyanobenzimidazoles from 3-and 4-quinolylnitrenes and 4-quinazolinylnitrenes, respectively. In compounds possessing nitro groups, chemical activation can cause the loss of the nitro group at nominal temperatures far below those normally needed to cleave the C-NO 2 bond.

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“…It is generally accepted that [Mn(CO) 5 ]· radicals are generated by the photolysis or thermolysis of [Mn 2 (CO) 10 ]. 26,27 In addition, cyclopropabenzenes reportedly decompose by the thermolysis 1 -3,28,29 and photolysis 30 to generate the corresponding biradical via the C-C bond cleavage in the cyclopropene ring.…”

Section: Thermal Reaction Of 1 With [Mn 2 (Co) 10 ]mentioning

confidence: 99%

“…heavier congeners of cyclopropane and cyclopropene. 7 -9 However, the chemistry of heteroatom analogs of cyclopropabenzene has been unexplored because of their low thermal stability except for some examples of heteracyclopropabenzenes such as aza-, 10 thia-, 11,12 selena-, 13 bora-, 14 and silacyclopropabenzenes 15 postulated as reactive intermediates. On the other hand, we have recently succeeded in the synthesis of the first stable sila- 16,17 and germacyclopropabenzenes, 18 by taking advantage of a combination of efficient steric protection groups, 2,4,6-tris[bis(trimethylsilyl)methyl]phenyl (Tbt) and 2,6-diisopropylphenyl (Dip), via the reactions of the corresponding overcrowded dilithiosilane 19 and dilithiogermane 18 with o-dibromobenzene, respectively.…”

Section: Introductionmentioning

confidence: 99%