Contrasting Reactivity of 2-chloro-1-formyl-3-hydroxymethylenecyclohexene and its Schiff Bases towards Disodium Diselenide: Isolation of Selenospirocycles versus Azapentalenes

Serendipitous Formation of Various Selenium Heterocycles Hidden in the Classical Synthesis of Selenophene

Synthesis of complex di(selenophen-3-yl)diselenides and 3-methylene-3H-1,2-diselenoles directly from 1-bromobutadiynes is described. The transformation is performed under conditions used before for the synthesis of simple selenophenes from butadiynes. The reaction is operationally straightforward, and complex products were obtained in high yields. Structures of the final products were unambiguously confirmed by the means of 77Se NMR and single-crystal X-ray diffraction.