Chirality solely due to the presence of an excited state

2-(Methoxymethylene)adamantane-4-one (I) was photoautoxidized to the dioxetane II (69% enantiomer excess); II decompd. thermally to give chiral excited 2,4-adamantanedione (III), the decay of which to achiral ground state III was characterized by circular polarization chemiluminescence. The racemization of excited III and the intramol. energy transfer assocd. with its decay are related to the UV and circularly polarized CD of III and the CD of III-18O. [on SciFinder (R)