Base-induced chemiluminescent decomposition of stereoisomeric 5-tert-butyl-1-(3-tert-butyldimethylsiloxy)phenyl-4,4-dimethyl-3-phenyl-2,6,7-trioxabicyclo[3.2.0]heptanes and their related dioxetanes

Singlet oxygenation of 4-tert-butyl-5-(3-tert-butyldimethylsiloxy)phenyl-3,3-dimethyl-2-phenyl-2,3-dihydrofuran (3a) in dichloromethane at 0°C gave a 95:5 mixture of stereoisomeric dioxetanes (anti-1a) and (syn-1a). The isomer (anti-1a) was more stable thermally than syn-1a. On treatment with tetrabutylammonium fluoride in DMSO or acetonitrile, both isomeric dioxetanes emitted intense blue light. Chemiluminescence efficiency (ΦCL) of anti-1a was considerably higher than that of syn-1a; nevertheless, both of them gave the very same couple of two carbonyl fragments (2a). A methyl-analog (1b) was also synthesized and its chemiluminescent properties were examined.