A reinvestigation of the photochemistry of 2-phenylcyclohexanone reveals that the two aldehyde products, cis-and trans-6-phenyl-5-hexanal, come from triplets of different lifetimes. That the two distinct triplets are not simply the two conformers with phenyl axial and equatorial is demonstrated by the similar behavior of cis-4-t-butyl-2-phenylcyclohexanone. The trans isomer of this ketone is photostable. It is concluded that trans-enal arises by an ...
