Yb(OTf) 3 catalyzed mild and regioselective ringopening 1,3-aminothiolation of donor−acceptor (D−A) cyclopropanes using sulfenamides has been demonstrated. The insertion of the C−C σ-bond of D−A cyclopropanes into the S−N σ-bond of sulfenamides allows the synthesis of diverse γ-aminated αthiolated malonic diesters in moderate to good yields (up to 87%) with good functional group compatibility. The stereospecificity of the reaction was demonstrated using enantiomerically pure D−A cyclopropane.