Photochemistry of Bridged and Unbridged Octaalkyl-Substituted syn-Tricyclo[4.2.0.02,5]octa-3,7-diene Derivatives
作者:Rolf Gleiter、Stefan Brand
DOI:10.1002/(sici)1521-3765(19981204)4:12<2532::aid-chem2532>3.0.co;2-6
日期:1998.12.4
The photochemistry of syn octamethyltricyclo[4.2.0.0(2.5)]octa-3,7-diene (1), its octaethyl congener 15, syn- 1,2,3,4,5,6,7,8,9,10,11,12-dodecahydro-8b, 12b-butanobenzo[3',4']cyclobuta-[1',2':3,4]cyclobuta[1,2-e]biphenylene (16) and syn-1,4,5,8,9,12-hexahydro-8b,12b-(but-3-eno)benzo[3',4']cyclobuta-[1',2':3,4]cyclobuta[1,2-e]biphenylene (17) was investigated. In the case of 1, six products were isolated. The main product was octamethylcuneane (19). As well as 6, the anti isomer of 1, octamethylcubane (18) was also found. The irradiation of 15 yielded a mixture of octaethylcubane (29) and octaethylcuneane (30), which could not be separated. The irradiation of 16 yielded five products, one of which (31) proved to be a propella[4(4)]prismane with averaged D-2d symmetry. A syn-anti isomerization to 38, and a photofragmentation to 39 was found when 17 was irradiated. In the case of 1, the mechanism of the reaction could be rationalized by involving either a biradical intermediate (40) or octamethylbicyclo[4.2.0]octa-2,4,7-triene (43). Support for the latter pathway was obtained by the detection of octamethylcyclooctaterraene (5) during irradiation.