20888-62-4Relevant academic research and scientific papers
Mechanistic variations in the formation of benzocyclooctatetraene from benzobicyclo[4.2.0]octa-2,4,7-triene
Bender, Christopher Owen
, p. 32 - 37 (1996)
Benzocyclooctatetraene (i.e., COT, 2) is the major product from the thermolysis and direct photolysis of 2,3-benzobicyclo[4.2.0]octa-2,4,7-triene (i.e., triene 1). It is also a minor product from the sensitized irradiation of 1. The mechanism of the reaction 1→2 was investigated using deuterium-labelled triene (i.e., 1a/b), which was prepared in a two-step procedure from a known triene mixture (1a) containing deuterium at both C-4 (43%) and C-5 (97%): the thermolysis of 1a led to labelled COT 2a, which upon direct irradiation (λ ≥ 310 nm) gave the deuterated triene mixture 1a/b in good chemical yield (61%) but in low quantum efficiency (Φ ≈ 0.0001). The COT produced from the direct irradiation (Corex filter) of 1a/b possessed different deuterium distributions than when generated thermally or from triplet sensitization (p-dimethylaminobenzophenone), as determined by 1H NMR integration. The observed deuterium-labelling patterns are in accord with a Zimmerman di-π-methane rearrangement being involved in formation of the COT from S1 of triene 1, while a mechanism proceeding by initial cleavage of the cyclobutene C1-C6 bond appears to operate during the thermal or sensitized (T1) generations of 2.
The photochemistry of 2,3-benzobicycloocta-2,4,7-triene
Asplund, Charlotte Lee,Bender, Christopher Owen,Dolman, Douglas
, p. 1999 - 2004 (2007/10/02)
2,3-Benzobicycloocta-2,4,7-triene (11) was prepared by Shapiro reaction from 2,3-benzobicycloocta-2,7-dien-4-one (10).Triene 11 was found to be thermally and photochemically reactive.Benzocyclooctatetraene (i.e., COT 12) was the unique product formed when solutions of 11 were heated at 150 deg C for 5.5 h.The direct irradiation of triene 11 gave benzosemibullvalene (i.e., SB 14, 23percent, Φ = 0.069), COT 12 (39percent, Φ = 0.11), and naphthalene (8percent, Φ = 0.025).Sensitized irradiations of 11 gave SB 14, (54percent, Φ = 0.082), COT 12 (2percent, Φ = 0.003), and naphthalene (4percent, Φ = 0.009).Studies with deuterium-labelled triene (11a) indicated that the formation of SB 14 from the direct irradiation of triene 11 derives from the operation of two reaction pathways, the major one (83percent) of which appears to be a Zimmerman di-?-methane rearrangement; the minor pathway involves a 1,2-shift of the C1-C6 bond to C1-C5.By contrast, SB 14 formed from sensitized irradiation appears to be provided uniquely by a Zimmerman di-?-methane rearrangement.
