5 (4H)-one, and phenylbutazone (33)] have been studied. After the introduction of a 1- hydroxycyclohexylamino group at the acidic position, five different stabilisation reactions of the intermediate 2 could be classified. The most important one is an intramolecular nucleophilic attack to a nitrile group giving disubstituted 1, 4-diazaspiro [4.5] decanones 2a. Their ring transformations (eg 2a+ 3) or the introduction of a second amino group at the ...