Formation of N-substituted pyrazoles from the pyrolysis of certain .alpha.,.beta.-unsaturated azines

Stern, Robert L.; Krause, Josef G.

doi:10.1021/jo01265a040

Cited by 9 publications

(11 citation statements)

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“…(14) See ref 3 for a discussion of the intramolecular facilitated solvolysis of an acetate located at position 9. tate appeared within 15 min after addition of the ethyl chloroformate. Filtration of the reaction mixture yielded 1.74 g of material characterized as 6a,8-diacetate hydrochloride 4-HC1, mp 269.5-270°d ec, by mixture melting point and comparison with the infrared spectrum of an authentic sample produced by adding diethyl ether saturated with hydrogen chloride gas to an ether solution of 6a,8-diacetate 4 and recrystallizing from ethyl alcohol-ethyl acetate. The infrared spectrum showed hydroxyl at 3340 and 3130 cm-1 and carbonyl at 1745 cm-1.…”

Section: Methodsmentioning

confidence: 99%

“…The viscous residue solidified upon treatment with Skellysolve B. The presence of 6a,8-diacetate 4 starting material was shown by thin layer chromatography. The infrared spectrum showed hydroxyl at 3490 cm-1 and carbonyl at 1760, 1735, and 1715 cm-1.…”

Section: Methodsmentioning

confidence: 99%

“…A. Formation of 1,3,4,6,6a,7,8,9,10, 10a, 11,1 la-Dodecahydro-2H -benzo [5] quinolizine -6a ,8,9,10a -tetrol 6a,8,9-Triacetate 10a-Ethyl Carbonate (8).-Using reported procedures,8 the mixture of compounds 4 and 6 was acetylated yielding a mixture of 6a,8,9-triacetate3 and 8. Several recrystallizations from Skellysolve B yielded an almost one spot material whose infrared spectrum was identical in all respects with that of the known material.8 B.…”

Section: Methodsmentioning

confidence: 99%

“…The compound under investigation was l,3,4,6,6a,7,8,9,10,10a,ll,lla-dodecahydro-2H-benzo [5]quinolizine-6a,8,9,10a-tetrol (1), and the tertiary hydroxyl was located at position 6a. 4 During the stereochemical elucidation of the all-axial tetrol 1, it was decided that one approach would be to form bridged structures of the two pairs of cis-1,3-diaxial hydroxyl groups. One method is to form a carbonate bridge using ethyl chloroformate.…”

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confidence: 99%

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Intramolecular facilitated acylation of a tertiary hydroxyl group in a perhydrobenzo[b]quinolizinetetrol

Block¹,

Nunes²

1970

J. Org. Chem.

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During the structure elucidation of 1,3,4,6,6a,7,8,9,10,10a,l l,lla-dodecahydro-2H-benzo[b] quinolizine-6a,8,9-loa-tetrol (l), a selective acylation of the tertiary loa-hydroxyl was observed. This reaction has been examined in more detail on the 6a18-diacetate derivative 4. It has been found that the acylation is solvent dependent. In pyridine, the secondary 9-hydroxyl is acylated with difficulty. In chloroform and tetrahydrofuran, the 10a-ethyl carbonate is obtained. Evidence is given for postulating that the acylation occurs directly by attack on the tertiary loa-hydroxyl with an assist by the secondary cis-9-hydroxyl and by what appears to be a long-range field effect of the ring nitrogen.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

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Intramolecular facilitated acylation of a tertiary hydroxyl group in a perhydrobenzo[b]quinolizinetetrol

Block¹,

Nunes²

1970

J. Org. Chem.

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“…When acetone azine is heated at 100 C in the presence of trace amounts of TiCl 3 , 90% conversion into pyrazoline 60 (R 1 ¼Me) is effected after 20 h [106]. Cinnamaldehyde azine and derivatives 61 are converted into pyrazoles 62 in high yields when heated at about 200 C (with or without solvent) (Scheme 8.14) [107]. Other a,b-unsaturated azines behave similarly [108,109].…”

Section: Formation Of One C-c Bondmentioning

confidence: 99%

Five‐Membered Heterocycles: 1,2‐Azoles. Part 1. Pyrazoles

Elguero

Silva

Tomé

2011

Modern Heterocyclic Chemistry

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1,5‐Diazabicyclo[3.3.0]octa‐2,6‐dien⇌4,5‐Diazaocta‐1,3,5,7‐tetraen Ein neues Valenzisomerenpaar und seine Rolle bei Pyrazol‐Synthesen

et al. 1979

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1,5-Diazabicyclo[3.3,O]octa-2,6-diene vom Typ 1 unterliegen sowohl bei der Thermolyse als auch bei der Photolyse einer Folge von elektrocyclischen Prozessen unter Bildung von 4,5-Diazaocta; 1,3,5,7-tetraenen 3. Der EinfluB des Substitutionsmusters auf die Auslosebedingungen der Reaktion sowie auf die Lage des Valenzisomeren-Gleichgewichts wird untersucht. Die Umsetzung von Aldazinen mit Alkinen fiihrt uber den beschriebenen ValenzisomerisierungsprozeB zu Pyrazolen. Der Mechanismus der Reaktion wird diskutiert. 1,5-Diazabicyclo[3.3.O]octa-2,6-diene 4,5-Diazaocta-1,3,5,7-tetraene A New Valence Isomeric Pair and its Part in Pyrazole Synthesis 1,5-Diazabicyclo[3.3,O]octa-2,6-dienes of type 1 undergo a sequence of electrocyclic reactions on thermolysis and photolysis to yield 4,5-diazaocta-1,3,5,7-tetraenes 3. The influence of the substitution pattern upon the conditions necessary for initiation of the reaction and upon the valence isomeric equilibrium is studied. The reaction of aldazines with alkynes yields pyrazoles via the described valence isomerization process. The reaction mechanism will be discussed.Bei der Synthese von 1,5-Diazabicyclo[3.3.O]octa-2,6-dienen aus Azinen und Alkinen -5 ) fanden wir in den Rohprodukten mit steigender Reaktionstemperatur zunehmende Mengen an 4,5-Diazaocta-l,3,5,7-tetraenen. In einer Reihe von FIllen konnten wir diesen Isomerisierungs-prozeD bereits bei Raumtemperatur bzw. wlhrend der saulenchromatographischen Auftrennung der Produktgemische an Kieselgel beobachten ' I. Wir nahmen diese Befunde zum AnlaD, die valenzisomere Beziehung des Paares 1,5-Diazabicyclo[3.3.O]octa-2,6-dien $4,5-Diazaocta-1,3,5,7tetraen zu untersuchen. Fur das Isomerenpaar 1,4-Dibenzoylbuta-l,3-dien + Furo[3,2-h]furan liegt das valenztautomere Gleichgewicht auch bei erhohter Temperatur ausschlieBlich auf der Seite des Bicyclus ", Das carbobicyclische Analogon ist bis 450°C stabil 'I. Synthese von 4,5-Diazaocta-l,3,5,7-tetraenen 4,4,8,8-Tetrakis(trifluormethyl)-l,5-diazabicyclo[3.3.0]octa-2,6-diene des Typs 1 unterliegen sowohl bei der Thermolyse als auch bei der Photolyse einer Umlagerung. Das aus 1 a durch zweistundiges Erhitzen auf 120°C hervorgehende Produkt zeigt im IR-Spektrum 0 Verlag Chemie, GmbH, D-

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Formation of N-substituted pyrazoles from the pyrolysis of certain .alpha.,.beta.-unsaturated azines

Cited by 9 publications

References 0 publications

Intramolecular facilitated acylation of a tertiary hydroxyl group in a perhydrobenzo[b]quinolizinetetrol

Intramolecular facilitated acylation of a tertiary hydroxyl group in a perhydrobenzo[b]quinolizinetetrol

Five‐Membered Heterocycles: 1,2‐Azoles. Part 1. Pyrazoles

1,5‐Diazabicyclo[3.3.0]octa‐2,6‐dien⇌4,5‐Diazaocta‐1,3,5,7‐tetraen Ein neues Valenzisomerenpaar und seine Rolle bei Pyrazol‐Synthesen

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