Dioxetanes, aryl substituted

At low temperatures dioxetane adducts with trivalent phosphorus have been isolated by Bartlett and coworkers. These cyclic phosphoranes gradually decompose to give the corresponding epoxide and phosphine oxide (Scheme 39) (73JA6486). Aryl-substituted phosphines... 

In the past few years two rather distinct classes of chemiluminescent dioxetanes have become evident. Alkyl, alkoxy, and simple aryl substituted dioxetanes, which includes the earliest dioxetanes prepared, are characterized... 

Several years ago it was noted that the behavior of dioxetanes substituted with large resonance groups (for example the dioxetanes postulated as intermediates in many bioluminescent reactions) is quite distinct from that of alkyl-, alkoxy-, or simple aryl-substituted dioxetanes (T. Wilson, 1976). The decomposition products of these dioxetanes are often highly fluorescent, possessing lowest excited ttti states, the yields of excited singlet states are often remarkably high, and the dioxetane stability is apparently low. It was suggested at that time that an alternative mechanism, perhaps a truly concerted mechanism, was operative. 

In 1982, the Schaap group demonstrated that chemiluminescence can be induced by the addition of a base to dioxetanes bearing a phenolic substituent [11]. Herein, the same group presents a method utilizing aryl esterase to catalyze the cleavage of a naphthyl acetate-substituted dioxetane in aqueous buffer at ambient... 

Schaap, A. P., Handley, R. S., and Giri, B. P., Chemical and enzymatic triggering of 1,2-dioxetanes 1 Aryl esterase-catalyzed chemiluminescence from a naphthyl acetate-substituted dioxetane. Tetrahedron Lett. 28, 935-938 (1987). 

One of the most powerful techniques to characterize 1,2-dioxetanes has been proton NMR. Thus, resonance of the dioxetane ring protons which are alkyl substituted are observed at 4.9-5.2 ppm.12 14,16 Dimethylamino substitution as in lw does not alter the chemical shift, since the ring proton resonance still occurs at 4.90 ppm.36b However, alkoxy substitution deshields the ring proton significantly, and the resonance occurs at 5.6-6.8 ppm.34 Aryl and olefinic substitution also shift the resonance to lower field, occurring at 5.6-5.9 ppm.14 36,37... 

---