Singlet oxygen oxygenation of enol ethers; the synthesis of optically active 1,2-dioxetanes. II

(+)-(Methoxymethylene)fenchane I (R = H, R1 = OMe) on singlet O oxidn. gave dioxetanes II and III, which on thermal decompn. underwent chemiluminescence in which (+)-fenchone was the only chemiluminescent species at lmax 420 nm. Photosensitized oxygenation of I (R = OMe, R1 = H) also gave 2 isomeric 1,2-dioxetanes. I were prepd. by Wittig methoxymethylenation of (+)-fenchone. Adamantanone (IV) on Wittig methoxymethylenation, followed by singlet O oxidn. gave dioxetane V, which on thermal decompn. gave only IV and HCO2Me and a bright blue chemiluminescence with lmax 420 nm and k1 2.96 * 10-3 s-1 at 79.9 Deg in decane. The prepn. of the dioxetanes allows the comparison of light- and chem. induced circular polarization of luminescence. [on SciFinder (R)

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)