83297-83-0Relevant academic research and scientific papers
Spectroscopic studies on effects of triptycyl group on structures and reactivities of triplet arylcarbenes
Tomioka, Hideo,Nakajima, Junichi,Mizuno, Hidehiko,Iiba, Eiji,Hirai, Katsuyuki
, p. 1066 - 1076 (2007/10/03)
A series of triplet 9-triptycyl(aryl)carbenes, where aryl groups are phenyl, 1- and 2-naphthyl, and 9-anthryl, is generated by photolysis of the corresponding diazomethanes and observed directly by spectroscopic means. Their structures are characterized by electron spin resonance (ESR) spectroscopy in a 2-methyltetrahydrofuran matrix at 77 K, and the reactivities are investigated by laser flash photolysis in degassed benzene solution at room temperature. Comparison of the data with other arylcarbenes bearing a series of substituents, i.e., hydrogen, phenyl, naphthyl, and anthryl groups, revealed an interesting relationship between structures and reactivities of triplet arylcarbenes.
Thermolysis and photolysis of 1-substituted triptycenes. Divergent fragmentation pathways of the triptycyl skeleton
Tomioka, Hideo,Nakajima, Junichi
, p. 563 - 569 (2007/10/03)
While thermolysis of 1-benzyltriptycene 1a in the gas phase at 600°C/10-4 mmHg did not result in any appreciable decomposition, similar pyrolysis of compounds 1 bearing various substituents (X) at the benzyl methylene (1b-d) underwent smooth decomposition to give 8-benzylbenz[a]aceanthrylene 2. The reaction is explained in terms of homolysis of the C-X bond followed by triptycyl ring cleavage in the resulting benzyl radical 7. Generation of radical 7 in solution, however, did not result in a similar ring-opening reaction. Irradiation of compounds 1, on the other hand, afforded norcaradienes 3 almost exclusively, obviously as a result of di-π-methane rearrangement. No products resulting from a carbene species proposed to be involved in the di-π-methane reaction of triptycenes were detected. Thermolysis of compounds 3 gave not only compound 2 but also benz[a]aceanthrylene 4 and benz[a]indeno[1,2,3-cd]azulene 5 whose compositions were found to be sensitive to both the substituent (X) and the thermolysis temperature. Mechanisms of the reactions are discussed in terms of the relationship between the thermal and photochemical fragmentations.
