The synthesis of monosubstituted 1,2,3-triazinium salts 7-9 and their reactivity towards C-nucleophiles is described. The nucleophilic attack at 7-9 is regioselective at position 5, isolation of dihydroproducts was possible and an unusual ring contraction was observed.
Herein, a chemoselective cascade addition reaction is reported, which starts from1,2,3-triazines and thiols to access several different α-substituted β-thio enals and their derivatives in a green and efficient synthesis. In terms of applications, readily available substrates, diversity of products, and mild reaction system make this strategy highly attractive.