Design and synthesis of chemiluminescent substrates with high luminescent efficiency in an aqueous system: 5-tert-butyl-4,4-dimethyl-2,6,7-trioxabicyclo[3.2.0]heptanes bearing a 3-hydroxy-4-(1-iminoethyl)phenyl moiety at the 1-position.

A CIEEL-active dioxetane bearing a 4-acetyl-3-hydroxyphenyl moiety has very recently been found to emit light effectively, even in an aqueous system, albeit with a very slow CIEEL decay rate. As an attempt to improve the CIEEL decay rate of this type of dioxetane, three dioxetanes, in which a carbonyl in the 4-acetyl-3-hydroxyphenyl moiety was modified into an oxime, oxime O-methyl ether, or semicarbazone, were synthesized. These three dioxetanes decomposed to emit light far more rapidly than the parent 4-acetyl-3-hydroxyphenyl-substituted dioxetane. Among them, a dioxetane bearing a 3-hydroxy-4-(1-methoxyiminoethyl) phenyl, namely an oxime O-methyl ether derivative, gave high chemiluminescent efficiency. As for a semicarbazone derivative, decrease of the chemiluminescent yield was minimal, even in an aqueous system. Copyright 2001 John Wiley & Sons, Ltd.