Herein a direct β-sulfido carbonyl compound synthesis by the easy activation of RS−Bpin reagents with α,β-unsaturated ketones and aldehydes is reported. This convenient methodology can be performed at room temperature with no other additives. The key point of this reactivity is based on the Lewis acidic properties of the boryl unit of the RS−Bpin reagent interacting with the C═O oxygen. Consequently, the SR unit becomes more nucleophilic and promotes the 1,4- versus the 1,2-addition, as a function of the involved substrate. The thioborated products can be further transformed into β-sulfido carbonyl compounds by addition of MeOH.