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Thermolytic Behavior of 4-Fold Bridged syn -Tricyclo[4.2.0.0 2,5 ]octa-3,7-dienes

1997; American Chemical Society; Volume: 62; Issue: 13 Linguagem: Inglês

10.1021/jo962393j

1520-6904

Stefan Brand, Rolf Gleiter,

Asymmetric Synthesis and Catalysis

The syntheses of the 4-fold-bridged compounds 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 (7), 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 (8), and 2,3,4,5,6,7,8,9,10,11,12,13,14,15-tetradecahydro-10b,15b-pentano-1H-cyclobuta[1",2":2,3;3",4":3',4']dicyclobuta[1,2:3,4:1',2']triscycloheptene (9) have been achieved starting from the cyclic diynes 10-12. Heating 7 and 8 at 200 degrees C without solvent leads to 1,2,3,4,5,6,7,8,9,10,11,12-dodecahydro-8b,12b-butanobenzo[3,4]cyclobuta[1,2-l]phenanthrene (18) and 1,4,5,8,9,12-hexahydro-8b,12b-(but-3-eno)benzo[3,4]cyclobuta[1,2-l]phenanthrene (19). Both systems contain a bridged bicyclo[4.2.0]octa-2,4,7-triene skeleton. The thermolysis of 9 yields (Delta(5a,5b;10a,11;11a,16a;17,17a))-2,3,4,5,6,7,8,9,10,12,13,14,15,16-tetradecahydro-11,17-pentano-1H-triscyclohepta[a,c,f]cyclooctene (20), a 4-fold-bridged cyclooctatetraene derivative. Treatment of 8 with DDQ leads to the dehydrogenation products 21 and 22. The different behavior in the thermolysis of 7 and 8 as compared to 9 is ascribed to the different lengths of the bridges.