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A solution containing 1.09 g (8.3 mmol) of 22 and 2.95 g (16.6 mmol) of .V-bromosuccinimide in 40 ml of carbon tetrachloride was refluxed for 2 hr and cooled to 0°. The succinimide was removed by filtration and the filtrate evaporated to leave 2.42 g (100%) of a pale yellow lachrymatory oil. This oil was dissolved in 50 ml of ether and 25 g of 0.8% lithium amalgam was added portionwise under argon. After 1.2 hr, the analysis showed no remaining dibromide. The excess amalgam and mercury were separated by decantation and the filtrate was evaporated at atmospheric pressure. The residual liquid was Paquette, et al. / Isomerization Reactions of Cyclooctatetraenes

Reaction of 7-bromo-c/s-bicyclo[4.3.0]nona-2,4-dien-8-one (la) as well as its 1,6-dimethyl (lb) and 1,6tetramethylene derivatives (2) with potassium /erf-butoxide in dimethyl sulfoxide for short periods of time at 25°r esults in dehydrobromination with structural bond reorganization to give bicyclo[4.2.1 ]nona-2,4,7-trien-9-ones (19, 21, and 26). Direct irradiation of these bridged ketones causes decarbonylation and cyclooctatetraenes are produced. When these molecules experience triplet sensitization, photoisomerization to barbaralones operates. 7-Chloro-8-thiabicyclo[4.3.0]nona-2,4-diene 8,8-dioxides rearrange in analogous fashion when treated with strong base in a polar aprotic solvent. The resulting bridged sulfones (34, 38, and 43) can be made to extrude sulfur dioxide by thermal or photochemical methods. These striking and unprecedented reactions provide a useful

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