18554-16-0Relevant academic research and scientific papers
Reaction of phenyl-substituted o-quinodimethanes with nitric oxide. Are benzocyclobutenes suitable precursors for nitric oxide cheletropic traps?
Paul, Thomas,Hassan, Mohammed A.,Korth, Hans-Gert,Sustmann, Reiner,Avila, David V.
, p. 6835 - 6848 (2007/10/03)
In order to elucidate the potential of substituted o-quinodimethanes as reagents for the trapping of nitric oxide (NO) in biological systems, the reaction of alkoxyl- and alkyl-substituted 7,8-diphenyl- and 7,7,8-triphenyl-o-quinodimethanes with nitric oxide in solution was investigated by ESR spectroscopic and UV/vis stopped-flow techniques. Photolytic decarbonylation of 1,3-diphenyl- and 1,1,3-triphenylindan-2-ones gave the corresponding phenyl-substituted benzocyclobutenes as the major products and low photostationary concentrations of o-quinodimethanes. During 266-nm laser flash photolysis (LFP) of 1,3-dimethoxy-1,3-diphenylindan-2-one and 1-methoxy-1,3,3-triphenylindan-2-one in acetonitrile, species absorbing in the 400-600 nm range were produced, which were attributed to configurational isomers of the corresponding 7,7,8,8-substituted o-quinodimethanes. The isomeric o-quinodimethanes decayed at significantly different rates, indicating a strong influence of the relative orientation of the terminal substituents on their stability. Reaction of the raw photolysates of the 2-indanones with NO produced strong ESR spectra of the corresponding cyclic nitroxide radicals, isoindolin-2-oxyls. The nitroxide radicals were generated in a two-phase process, the first, rapid phase being attributed to the reaction of NO with the photolytically formed o-quinodimethanes and the second, slow phase reflecting the reaction with small amounts of o-quinodimethanes, generated by thermal ring opening of the phenyl-substituted benzocyclobutenes and probably a direct reaction of NO with the benzocyclobutenes. The kinetics of both steps, as evaluated by stopped-flow UV/vis and ESR spectroscopy, revealed a strong dependence of the rate constants of the o-quinodimethane ± NO reaction on the substitution pattern of the o-quinodimethanes, with rate constants spanning a range of 10-4000 M-1 s-1. The rate constants ((0.4-7.5) x 10-4 s-1) for the reaction of NO with the 7,7,8,8-tetrasubstituted benzocyclobutenes are much less influenced by the substitution pattern. The utility of phenyl-substituted benzocyclobutenes as 'reservoirs' for o-quinodimethane-type nitric oxide traps is discussed.
Photochemistry of 1,1,3-triphenyl-2-indanone. Spontaneous and photochemical decay of ortho-xylylenes
Netto-Ferreira,Wintgens,Scaiano
, p. 6851 - 6854 (2007/10/02)
The photochemistry of the title compound leads to the formation of a long lived ortho-xylylene which decays by two competing cyclization pathways leading to benzocyclobutene and dihydroanthracene ring systems. The ratio of products V and VI is different for one and two-photon processes, thus providing another example where the products can be controlled by the type of photoexcitation used.
