Selective Synthesis of Bis-Heterocycles via Mono- and Di-Selenylation of Pyrazoles and Other Heteroarenes.

The insertion of selenium was achieved in the form of mono-selenides and di-selenides for the preparation of novel bis-heterocyclic compounds. This method is more general and provides scaffold diversity with high yields of products. The concentration-dependent mono- and di-selenylation reaction selectivity was achieved using SeO 2 as an efficient selenylating reagent.