The present invention provides 3- to 7-membered 1,3-diaza-4-oxo-heterocyclic derivatives, such as imidazolidinone O derivatives, capable of releasing in a controlled manner a biologically active aldehyde or ketone in the surrounding. The invention also relates to the use of these compounds as perfuming or flavoring ingredients, as well as to the perfuming compositions and consumer articles containing such derivatives. It also provides a process for preparing said derivatives of the invention