Efficient Palladium-Catalyzed Synthesis of Unsymmetrical (Het)aryl­tetrazines

Palladium-catalyzed copper(I)-mediated cross-coupling reaction of 3-methylthio-6-(morpholin-4-yl)-1,2,4,5-tetrazine with a wide range of boronic acids and organotin derivatives led to new unsymmetrical aryl- and hetaryl-substituted tetrazines in moderate to good yields. These results represent the first cross-coupling reactions of readily available 3-methylthiotetrazine under Suzuki-like and Stille-like conditions and could extend the scope of tetrazine chemistry.