Аннотация:Irreversible two‐photon photorearrangement of 1,2‐diarylethenes is a unique process providing access to complex 2a<jats:sup>1</jats:sup>,5a‐dihydro‐5,6‐dithiaacenaphthylene (DDA) heterocyclic core. This reaction was serendipitously discovered during studies on photoswitchable diarylethenes and was initially considered as a highly undesired process. However, in recent years, it has been recognized as an efficient photochemical reaction, interesting by itself and as a promising synthetic method for the synthesis of challenging molecules. Herein, we discuss the state‐of‐the‐art in studies on this notable process