Photochemistry of a,, L?-epoxy-eucarvone.-Surizmary. On.-c, z*-excitation (A= 254 nni) 4 isomerizes to the hicyclic kctoaldehyde 5; on n, a*-excitation (I,> 280 nm) 4 gives5, thep, yunsaturatcd ketone 6, the enone 7 and the cyclobutanone 8. Scission of the (CC)-bond of the oxirane 4 would give the dihydrofurane e, which could isomerize to the Betoaldehyde 5. On the other hand, 4 is assumed to isomerize to the/3, y-unsaturatcd aldehyde c, which ...