Neue Azoolefine und deren saure Spaltung zu Aryldiiminen

Kirschke, Klaus; Möller, Angela; Schmitz, Ernst

doi:10.1002/prac.19853270604

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Reactions Of α-Haloketones With Alkenes and Alkynes1

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2009

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Cited by 11 publications

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“…Methyl 3-amino-3-arylazopropenates 285 react with α-haloketones in the presence of 1,8-diazabi-cyclo[5.4.0]undec-7-ene (DBU) to furnish the pyrrole derivatives 286 on the pattern of the Hantzch-pyrrole synthesis ( Scheme 84 ) [ 536 , 537 ].…”

Section: Reactions Of α-Haloketones With Alkenes and Alkynesmentioning

confidence: 99%

The Chemistry of α-Haloketones and Their Utility in Heterocyclic Synthesis

2003

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Section: Reactions Of α-Haloketones With Alkenes and Alkynesmentioning

confidence: 99%

The Chemistry of α-Haloketones and Their Utility in Heterocyclic Synthesis

2003

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Synthesis and Reactions of Hydrazo, Azo and Azoxy Compounds

Boyd

2009

Patai's Chemistry of Functional Groups

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Ring Transformations of Pyrazolones Via Azo‐Olefins

Schmitz¹,

Lutze²,

Kirschke³

et al. 1992

Bulletin des Soc Chimique

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Instead of substitution, 4-halo-pyrazolones undergo ring opening to azo-olefins (2,U,B) on reaction with nucleophiles. Attempted Hofmann degradation of N-Haloamides 4 has to compete with either ring closure, involving NHCI-shift to z, or formation of mesoionic compounds 19, whose pyrazolone ring shows a different pattern of nitrogen insertion. Substitution of cyclic amines for chlorine in azo-olefin a is followed by rearrangement to the bicycle 15. Access to 1,2,3-thiadiazolium salts (I.& 22) is possible by electrophilic attack of sulfur reagents to azo-olefins.4,4-Dihalo-pyrazolones react with nucleophiles by ring opening to unsaturated azo compounds; ester 2, for example, is formed from dibromo-pyrazolone 1 on the action of methoxide. A reverse reaction was also observed : Morpholine converts 2 to the pyrazolone This Hofmann degradation had to compete with a shift of the chloramine group in the course of a pyrazolone formation yielding chlorimino pyrazolones 2. Action of ammonia to 2 gave the triazole 9. Obviously the pyrazolone ring was opened by ammonia to give 8, which cyclized to 9 with chloride ion elimination.A third reaction type was observed in several cases which competed successfully with Hofmann degradation :N-N-bond formation between the chlorine bearing nitrogen and an azo nitrogen in 4 lead to the deep red mesoionic 1p. The structure of j & was confirmed by an X-ray analysis. It is noteworthy that the new pyrazolones 1Q have incorporated only one of the nitrogen atoms of the starting pyrazolone, the other comes from the acid amide group.In an attempt to parallel the reaction of 2 to 3 using pyrrolidine in place of morpholine, azo olefine Q was not the final product. Its isomer L5 was isolated instead.Piperidine reacted analogously.-6 1 -

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Neue Azoolefine und deren saure Spaltung zu Aryldiiminen

Cited by 11 publications

References 17 publications

The Chemistry of α-Haloketones and Their Utility in Heterocyclic Synthesis

The Chemistry of α-Haloketones and Their Utility in Heterocyclic Synthesis

Synthesis and Reactions of Hydrazo, Azo and Azoxy Compounds

Ring Transformations of Pyrazolones Via Azo‐Olefins

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