Synthetic Approaches to Bis(Chloromethylidene) Substituted Six-Membered Rings with Two Heteroatoms Including S, Se, N in Various Combinations

Six-membered chalcogen, element (S, Se, N)-containing heterocycles attracted attention due to their biological activities. This mini-review presents methods for the preparation of these heterocycles modified by introduction of two chloromethylidene groups into their molecules. Methods for the synthesis of bis(1,3-dihalogeno-1-propen-2-yl) chalcogenides and their oxides, and methods of their heterocyclization with sodium sulfide and selenide, hydrazine and amine are reviewed as well as subsequent chemical transformation of the resulting heterocycles. Due to the presence of these moieties, further modifications of these heterocycles by the nucleophilic substitution and cross-coupling reactions are possible and presented in the mini-review. Keywords: Propargyl halide, sulfur dichloride, selenium dihalide, chloromethylidene group, 1, 4-dichalcogenane, N-organyl chalcogenomorpholine, chalcogenomorpholinamine, hydrazine.