C. Asplund, C. Bender, D. Dolman
Sep 1, 1994
Citations
0
Influential Citations
4
Citations
Journal
Canadian Journal of Chemistry
Abstract
2,3-Benzobicyclo[4.2.0]octa-2,4,7-triene (11) was prepared by Shapiro reaction from 2,3-benzobicyclo[4.2.0]octa-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 °C for 5.5 h. The direct irradiation of triene 11 gave benzosemibullvalene (i.e., SB 14, 23%, Φ = 0.069), COT 12 (39%, Φ = 0.11), and naphthalene (8%, Φ = 0.025). Sensitized irradiations of 11 gave SB 14, (54%, Φ = 0.082), COT 12 (2%, Φ = 0.003), and naphthalene (4%, 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 (83%) of which appears to be a Zimmerman di-π-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-π-...