Compounds of the general formula Ia and Ib are described ##STR1## in which R.sup.1 and R.sup.2 are the same or different and represent hydrogen, straight-chain or branched C.sub.1 to C.sub.6 lower alkyl or an aryl group optionally substituted by electron-withdrawing groups, R.sup.3 denotes a cleavable group, W is hydrogen, halogen or a pseudohalogen and at least one of the groups R.sup.4 or R.sup.5 is a group stabilizing the dioxetane structure and at most one of the groups R.sup.4 or R.sup.5 represents hydrogen and X or Y represents oxygen, N-R or C(R).sub.2 in which R has the meanings stated for R.sup.1 and R.sup.2 or represents a mesomeric double bond or a carbonyl group and n denotes the number 0 or 1 and m denotes the number 1 or 2, as well as a process for their production. These compounds are new and can be used as substrates in immunological assays and in DNA diagnostics using activating agents for colour formation.