Ein Beitrag zum Mechanismus der Singulett-Photoisomerisierung des Homofulven-Systems

Lehrstuhl für Organische Chemie I der Universität Ulm, Oberer Eselsberg, D-7900 U l m Z. Naturforsch. 3 4 b , 1133-1139 (1979); eingegangen am 26. Apri l 1979 Photoisomerizat ion, H o m o f u l v e n e Systems The isomerizations fol lowing the singlet excitation of l ,2,3,5-ea:o-6-pentamethyl-4methylene-b icyc lo [3 , l ,0 ]hex-2 -ene (exo-1) and l ,2 ,3,5-endo-6-pentamethyl-4-methyleneb icyc lo [3 , l ,0 ]hex-2 -ene (endo-1) are studied quantitatively. Besides an reversible endo-exo isomerization exo-1 and endo-1 form hexamethylbenzene via 1 ,2,3,4,6-pentamethyl-5methylene-cyc lohexal ,3 -d iene as an isolable intermediate.