2,2 ,6,6 -tetraphenyl

The fragmentation pattern of 4 has been studied in detail, using deuterium labeling. The patterns for 37 and its 2H analog are essentially the same, though quite different from that of 1,2,4,5-tetraphenyl-lff-imidazole. ... 

Bei 1-substituierten Imidazolen scheint die Ringoffnung im allgemeinen bevorzugt zu sein. So fiihrt die Oxidation von 1,2,4,5-Tetraphenyl-imidazol mit Singulett-Sauerstoff in Methanol in 97% Ausbeute zu N,N-Dibenzoyl-N-phenyl-benzamidin1233. 

Selenium has been found to be an efficient hydrogen acceptor in the dehydrogenation of 2-aryl-2-imidazolines to 2-arylimidazoles. When 2,4,4,5-tetraphenyl-4H-imidazole is heated, it rearranges to the 1,2,4,5-tetraphenyl isomer. ... 

Disubstituted cyclopropenes do not react in the above sence. 1,2-dimethyl-cyclopropene polymerizes at 0 °C in the presence of [(T)3-C3H5)PdCl]2 30). 1,2-Diphenylcyclopropene cyclodimerizes nearly quantitatively in the presence of Pd(dba)2 or Pd(r)5-C5H5)(r 3-C3H5) to yield 1,2,4,5-tetraphenyl-cyclohexa-1,4-diene 72) (see p. 96). 

Besonders schnell verlaufen die Dimerisierungen von III und VII zu VI und 3-(r-l,c-2-c-3-Triphenyl-cydopropyl)-l,2,3-triphenyl-cyclopropen (Verh. 60 40) sowic VIII, wenn mit Thioxanthon (ET = 65 kcal/Mol) in Benzol sensibilisiert wird2. Entsprechend erhalt man aus 1,2-Diphenyl-cyclopropen bei -78° in Dichlormethan 1,2,4,6-Tetraphenyl-mUi-tricyclo[3.1.0.02 ]hexan. Dieses liefert schon beim Erwarmen auf 13° 1,2,4,5-Tetraphenyl-cyclohexadie.n-ll,4) (F 257-258,5°)2 ... 

Diphenylcyclopropene cyclodimerizes nearly quantitatively in the presence of Pd(dba)2 or PdCri -CjHjXri -CjHj) to yield 1,2,4,5-tetraphenyl-cyclohexa-1,4-diene (see p. 96). 

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