tert‐Butyl Nitrite‐Mediated Deaminative Chalcogenation of Substituted 5‐Aminopyrazoles via Diaryl Dichalcogenides

Abstract An expedited route to the synthesis of substituted 5‐(arylselanyl)‐1 H ‐pyrazoles and substituted 5‐(arylthio)‐1 H ‐pyrazoles via reaction between substituted 5‐amino‐1 H ‐pyrazoles bearing an electron withdrawing group (EWG) at C‐4 and diaryl dichalcogenides in the presence of tert ‐butyl nitrite is described. The protocol is compatible with substrates bearing different EWGs, such as carboxylate, nitrile or phenylsulfonyl. The strategy works even with substituted 5‐amino‐1 H ‐1,2,3‐triazoles to furnish the corresponding chalcogenides. The mechanism of the reaction is postulated to involve a radical pathway.