Conjugateaddition to 1,4-dicarbonylbut-2-enes will generate an α-stereogenic center with respect to one of the carbonyl groups, which informally, can be considered as an inversion of normal reactivity patterns or umpolung protocol. In this paper, the addition of tert-butyl mercaptan to 1,4-dicarbonylbut-2-enes including (E)-4-oxo-4-arylbutenamides and (E)-4-oxo-4-arylbutenones has been developed,