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By introducing a selenium(IV) group into the coupling position of anilinopyrazolones and naphthols, for example with SeO2, it is possible for the first time to convert the corresponding 4-equivalent couplers directly into 2-equivalent couplers with a triazole leaving group. Thus treatment of 1 with SeO2 yields 2, which reacts with a benzotriazole by selenium cleavage to afford 3.
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Peter Bergthaller (1991) studied this question.
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