Performance of select metal triflates in the enantioselective Michael reaction compared to the individual metals' ionic radii^a.

Entry	Metal ion	r (Å)	Solvent	Time (h)	Yield 6 (%)	ee (%)
1	Sc3+	0.870	DCE	96	31	90 (S)
2			Benzene	96	Trace	—
3	Y3+	1.019	DCE	18	92	71 (R)
4			Benzene	18	91	91 (R)
5	Dy3+	1.027	DCE	17	88	76 (R)
6			Benzene	17	83	90 (R)
7	La3+	1.160	DCE	14	93	60 (S)
8			Benzene	14	97	43 (S)

^aConditions: 10 mol% 1 and 5 mol% M(OTf)₃ were pre-stirred at 60 °C (1 h). Reactions were performed on 0.15 mmol scale in the listed solvent (0.02 M) at 60 °C for the listed time.