34950-38-4Relevant articles and documents
Purported synthesis of 3,4,7,8-tetraphenyl-1,2,5,6-tetraazocine from benzil and hydrazine: Competing cyclization and carbon-carbon σ-bond scission
Eisch, John J.,Chan, Tsz Y.,Gitua, John N.
, p. 392 - 397 (2008/09/18)
The claims that 3,4,7,8-tetraphenyl-1,2,5,6-tetraazocine can be prepared by the thermal condensation of two moles of benzil monohydrazone or of an equimolar mixture of benzil and benzil dihydrazone have been thoroughly reinvestigated. When such thermolyses were conducted in moist air, neither the claimed 3,4,7,8-tetraphenyl-1,2,5,6-tetraazocine nor the precedented isomeric tetraazapentalene derivative was detected. The following products were unambiguously formed from the heating of molten benzil monohydrazone (%): benzil (10), benzaldehyde (10), benzamide (22), benzyl phenyl ketone (19), benzil bis(ketazine) (11), 3,4,5,6-tetraphenylpyridazine (9), benzil benzaldehyde azine (10), and, after column chromatography, 2,4,5-triphenylimidazole (2). This last component had a melting point and the fluorescent properties in UV light attributed by the original investigator to the mistakenly presumed 3,4,7,8-tetraphenyl-1,2,5,6-tetraazocine. Thus, the original claims for the synthesis of such a novel tetraazocine ring or even for the synthesis of the precedented isomeric zwitterionic tetraazapentalene have now been repudiated. The formation of 2,4,5-triphenylimidazole as a side reaction in the thermolysis of benzil monohydrazone can readily be rationalized as arising from benzil, benzaldehyde, and a source of ammonia, namely, benzamide, in the long-known Radziszewski reaction. Corroborating evidence was provided by data from the thermolysis of benzil dihydrazone. In addition, the origin of other side products is explained in terms of other possible condensations. Finally, preliminary experiments on using irreversible dehydrating agents such as titanium(IV) isopropoxide with benzil monohydrazone indicate that 3,4,7,8-tetraphenyl-1,2,5,6-tetraazocine is formed at room temperature as a transitory intermediate, which eliminates dinitrogen to produce 3,4,5,6-tetraphenylpyridazine. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
Synthesis of 1,4-Diazidobuta-1,3-dienes by Electrocyclic Ring Opening: Precursors for Bi-2H-azirin-2-yls and Their Valence Isomerization to Diazabenzenes
Banert, Klaus,Koehler, Frank
, p. 174 - 177 (2007/10/03)
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Reactions of cobaltacyclopentadiene complexes with organic azides directed toward synthesis of highly substituted pyrroles
Hong, Pangbu,Yamazaki, Hiroshi
, p. 133 - 142 (2007/10/02)
The reactions of the cobaltacyclopentadiene complexes (η5-C5H5)(PPH3)-Co(-CR1=CR2-CR3=CR4)- (I) with organic azides were investigated.The complex Ia (R1)=R2=R3=R4=Ph) reacts with phenyl azide at 80 degC to give 1,2,3,4,5-pentaphenylpyrrole in 73percent yeld.Similarly, the reactions of Ia with benzoyl and t-butoxycarbonyl azides give 1-benzoyl- and 1-(t-butoxycarbonyl)-2,3,4,5-tetraphenylpyrroles in 41 and 64percent yields, respectively, but reaction with p-toluenesulfonyl azide gives 2,3,4,5-tetraphenylpyrrole and 3,4,5,6-tetraphenylpyridazine in 35 and 45percent yields, respectively, in place of the expected 1-(p-toluenesulfonyl)-2,3,4,5-tetraphenylpyrrole.The reaction of Ic (R1=R4=Ph, R2=R3=CO2CH3) with phenyl azide at 130 degC gives 1,2,5-triphenyl-3,4-bis(methoxycarbonyl)pyrrole (IIc)and 2,5-diphenyl-3,4-bis(methoxcarbonylpyrrole (Vb) in 22 and 15percent yields, respectively.The reaction of Ic with benzenesulfonyl azide gives only Vb in 57percent yield.In the reaction of Id (R1=R3=Ph, R2=R4=CO2CH3) with benzenesulfonyl azide, Vb was unexpectedly obtained in 26percent yield, together with 2,4-diphenyl-3,5-bis(methoxycarbonyl)pyrrole (Vc, 30percent), which suggests that a skeletal rearrangement of the metallacycle IXd to IXc occurs during the reaction.The reaction of Ic or Id with benzoyl azide at 130 degC gives the 2(1H)-pyridinone derivatives VIIIa (82percent) and VIIIb (53percent), which are the products of the reaction of the corresponding cobaltacyclpentadiene with phenyl isocyanate generated by the rearrangement of benzoyl nitrene, in place of the expected, corresponding pyrrole.
