To obtain a 1,2-dioxacene suitable for production of substituted 1,2- dioxetanes and useful as a readily handleable intermediate.

This compound is represented by the formula [T is a group forming a stabilizing group which is a cycloalkylidene or a fused polycycloalkylidene binding through a spiro bond to the 3-carbon atom of dioxetane ring; W- is an acid anion; R1 is a 1-20C alkyl, aralkyl or a cycloalkyl; Y is a fluorescent chromophore which is residue of the following compound (including its derivative): benzene, naphthalene, anthracene, rhodamine, fluoresceine, eosin, coumarin, erythrocin, benzheteroazole, pyrene, stilbene, nitrobenzoxadiazole, quinoline, acridine, acid acridine, carbazole, fluorescent cyanine, carbocyanine, pyridinium, oxonol, resorofine or hydroxyresorofine]. The compound of the formula is synthesized by using a compound of the formula T-CN as a starting compound.