Eine Methode zur Identifizierung von aus unsymmetrischen β‐Diketonen und Hydrazinderivaten erhältlichen Pyrazolderivaten

Eistert, Bernd; Wessendorf, Richard

doi:10.1002/cber.19610941003

Cited by 16 publications

(4 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The yields, physical properties and analytical data of the previously unreported compounds are given in Table 6. The following compounds have been previously reported but their isomeric distributions were not reported: 1-pyrrolidino-2(or 5)-acetylcyclopentene (2a) [26]; 1-morpholino-2(or 5)-acetylcyclopentene (2c) [4] 1-(3-azabicyclo[3.2.2]nonylamino-2(or 5)-methylcyclohexene (1f) [27].…”

Section: Methodsmentioning

confidence: 99%

“…( We produced cyclohexenyl enamines with acetyl substituents in the 2-and 6-positions and cyclopentenyl enamines with acetyl substituents in the 2-and 5-positions in two different ways. They were synthesized by direct carbon acylation of the enamine [3,4] and by reaction of an acetylcycloalkanone with a secondary amine [5,6] (Scheme 1). We have found that the isomeric distributions of enaminoketones 1 and 2 are essentially the same for each of the two alternative methods of synthesis.…”

mentioning

confidence: 99%

“…They were synthesized by direct carbon acylation of the enamine [3,4] and by reaction of an acetylcycloalkanone with a secondary amine [5,6] (Scheme 1). We have found that the isomeric distributions of enaminoketones 1 and 2 are essentially the same for each of the two alternative methods of synthesis.…”

mentioning

confidence: 99%

See 2 more Smart Citations

Isomer Distribution of Succinylcyclohexenyl, Acetylcyclohexenyl and Acetylcyclopentenyl Enamines

Cook¹,

Folk

2008

LOC

View full text Add to dashboard Cite

The isomeric distributions of some cyclohexenyl enamines substituted by succinyl or acetyl groups at either the 2-or 6-positions are reported as are the isomeric distributions of similarly substituted cyclopentenyl enamines. Correlation between the 13 C NMR chemical shifts in these enamines and isomer distribution is shown. Density functional molecular modeling is used to demonstrate resonance and electrostatic effects on isomeric distributions.One of the most common methods of synthesizing cyclohexenyl and cyclopentenyl enamines is to allow a cyclohexanone or a cyclopentanone compound to react with a secondary amine [1,2]. If the enamine is unsymmetrically substituted at the 2,6-positions (cyclohexenyl) or at the 2,5-positions (cyclopentenyl), two different isomers may be produced, namely tet and tri (Eq. 1) with the latter present as two different conformers in the cyclohexenyl case, tri ax (substituted X is pseudoaxial) and tri eq (substituted X is pseudoequatorial).We produced cyclohexenyl enamines with acetyl substituents in the 2-and 6-positions and cyclopentenyl enamines with acetyl substituents in the 2-and 5-positions in two different ways. They were synthesized by direct carbon acylation of the enamine [3,4] and by reaction of an acetylcycloalkanone with a secondary amine [5,6] (Scheme 1). We have found that the isomeric distributions of enaminoketones 1 and 2 are essentially the same for each of the two alternative methods of synthesis. We have further discovered that the second method (acetylcycloalkane with a secondary amine) also produces an amide. For example amide 5 is produced along with acylated cyclic enamines 1 and 2 when this method is used. Production of amides from enamines by the reaction of acyl halides with enamines has been reported before [7], but this reaction involves different reagents and so follows a different mechanistic pathway. These amides are probably produced by way of initial formation of pseudobase 3 or 4 followed by elimination of amide 5 in a retro condensation reaction. Further proof for this mechanism is shown by the appearance of significant amounts of simple cyclic ketones and simple enamines in the crude reaction products as determined by GC-MS. A similar reaction has been reported with the reaction of pyrrolidine with acetylacetone under microwave conditions [8]. The yields of amides represent the amount of alternate enaminoketone (with an exocyclic double bond due to attack of the acetyl carbonyl by the amine) which would have formed if the retro reaction to form amide 5 did not take place. + + 1 tet, n=1 1 tri, n=1 2 tet, n=0 2 tri, n=0 + + 3, n=1 4, n=0 5 + Scheme 1.The isomeric distributions of products for these reactions are given in Tables 1 and 2 along with the isomeric distribution of some previously unreported or erroneously reported enamines of 2-methyl-and 3-phenylcyclohexanones.The relative amounts of the isomers were determined by using 13 C NMR in CDCl 3 solvent with a long relaxation delay. The pseudo-equatorial and pseudo-axial configurational iden...

show abstract

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

Isomer Distribution of Succinylcyclohexenyl, Acetylcyclohexenyl and Acetylcyclopentenyl Enamines

Cook¹,

Folk

2008

LOC

View full text Add to dashboard Cite

show abstract

“…Saturated bicyclic pyrazoles are typically prepared by the Knorr condensation of a hydrazine derivative with a 1,3-dicarbonyl compound − ,− (Scheme a) or an equivalent substrate. ,− Alternative procedures involve variations of the 1,3-dipolar cycloaddition (Scheme b). − ,− The main drawback of these methods lies in the often laborious preparation of the required starting materials, which can limit the available functionality in the product and precludes the late-stage introduction of structural diversity. In addition, some saturated heterocyclic systems have been noted to give unexpected rearrangement products under Knorr condensation conditions …”

Section: Introductionmentioning

confidence: 99%

Regioselective Preparation of Saturated Spirocyclic and Ring-Expanded Fused Pyrazoles

et al. 2014

View full text Add to dashboard Cite

Saturated bicyclic pyrazoles represent an important class of biologically active molecules, but their preparation can be hampered by labor-intensive synthesis of required starting materials. A convenient one- or two-step procedure for the synthesis of saturated spirocyclic and fused pyrazoles is reported. The synthesis benefits from the use of readily available alkynes and bench-stable tosylhydrazones, which are easily prepared from their parent ketones. Sigmatropic rearrangement of spirocyclic pyrazoles to fused analogues occurs with concomitant one-carbon expansion of the saturated ring, allowing rapid access to a range of pharmaceutically and agrochemically relevant polycyclic structures featuring a broad scope of saturated ring sizes.

show abstract

Derivate von 4,5,6,7‐Tetrahydroindazol 2. Mitt.

Schlager

1964

Archiv der Pharmazie

View full text Add to dashboard Cite

Schlager AMV der Pharmade gen ein, bevor der eigentliche Vmuch gestartet werden kann. Hierbei kommt es vor allem zur Bildung von Rheindianthron, wie chromatographieche Analyeen zeigten. Die spektrophotometriechen Measungen d e n in 1-cm-Kuvetten mit einem Spektralphotometer der Firma Carl Zeip, Modell PMQ 11, oder mit einem eelbstregistrierenden Spektdphotometer der Firma Beekman, Modell DK-lA, durchgefiihrt. PC: Whatman I, Methanol-Waaeeer (1 + 1); DC: Kieeelgel G ,,Merck", Toluol-Athylformiat-Ameieensiiure (6 + 4 + 1); Sichtbarmachen der Flecke durch Beetrahlen rnit W-Licht und Beapriihen mit methanol. KOH. Rhein wurde in Anlehnung an die Vorschrift von Horhammer, Wagner und K0hk+4) aus Rhiz. Rhei gewonnen. Hieraus wurde durch Reduktion mit Zinn(I1)-chlorid das Rheinanthron nach Croee und Perkids) hergestellt. Rheindianthron erhielten wir durch Oxydation von Rheinanthron mit FeC1, in EiRessigB) und durch Hydrolyee von Sennosiden. Ale Ferment verwendetsn wir Meerrettichperoxydasa der Firma C. F. Boehringer u. Sohne, deren Aktivitiit in friiher beachriebener Weiee b e a t i i t wurde14). Dem Fonds der Chemiechen Industrie d d e n wir fiir die Unterstutzung dieser Arbeit durch die Gewiihrung von Forschungebeihilfen, der Firma Handoz fiir die zur Verfugung geetellten Sennoside.

show abstract

Eine Methode zur Identifizierung von aus unsymmetrischen β‐Diketonen und Hydrazinderivaten erhältlichen Pyrazolderivaten

Cited by 16 publications

References 6 publications

Isomer Distribution of Succinylcyclohexenyl, Acetylcyclohexenyl and Acetylcyclopentenyl Enamines

Isomer Distribution of Succinylcyclohexenyl, Acetylcyclohexenyl and Acetylcyclopentenyl Enamines

Regioselective Preparation of Saturated Spirocyclic and Ring-Expanded Fused Pyrazoles

Derivate von 4,5,6,7‐Tetrahydroindazol 2. Mitt.

Contact Info

Product

Resources

About