Procedure-controlled selective synthesis of 5-acyl-2-iminothiazolines and their selenium and tellurium derivatives by convergent tandem annulation.

Concise and selective: the procedure-controlled synthesis of the title compounds has been achieved for the first time by an organolithium-promoted convergent tandem annulation involving readily available terminal alkynes, chalcogen elements (S, Se, and Te), carbodiimides, and acid chlorides. A novel 1,5-acyl migration is considered to be essential for this useful transformation.