Recent progress in the application of five-membered heterocyclic analogues of the nitrobutadiene in cycloaddition reactions (microreview)

In this microreview, recent progress in the application of selected five-membered heterocyclic analogues of nitrobutadiene, namely nitrofurans, nitrothiophenes, and nitroselenophenes, in reactions of cycloaddition is summarized. The collected data demonstrate that this research area remains relatively unexplored, with only a limited number of reported examples. Most of the available studies concern (3+2), (4+2), and (4+3) cycloaddition processes, with the title compounds most frequently acting as dienophile in Diels-Alder reaction. Among the investigated substrates, 2‑nitrofuran has been employed most extensively, whereas 2‑nitrothiophene and 2‑nitroselenophene have been used much less frequently. 3‑nitro-substituted analogues have been examined only for thiophene and selenophene.