Condition optimization^a.

Entry	Acid	Solvent	Model	Conv.b (%)	eec (%)
1	—	1,4-Dioxane	—	<5	—
2	Sm(OTf)3	1,4-Dioxane	—	<5	—
3	—	1,4-Dioxane	(Sp)-6a	<5	—
4	Yb(OTf)3	1,4-Dioxane	(Sp)-6a	73	93
5	Zn(OTf)2	1,4-Dioxane	(Sp)-6a	9	92
6	La(OTf)3	1,4-Dioxane	(Sp)-6a	26	92
7	Sm(OTf)3	1,4-Dioxane	(Sp)-6a	86	94
8	Sm(OTf)3	THF	(Sp)-6a	74	93
9	Sm(OTf)3	CHCl3	(Sp)-6a	89	65
10	Sm(OTf)3	Toluene	(Sp)-6a	78	88
11	Sm(OTf)3	EA	(Sp)-6a	94	93
12	Sm(OTf)3	EA	(Sp)-6b	>95	93
13	Sm(OTf)3	EA	(Sp)-6c	>95	95
14	Sm(OTf)3	EA	(Sp)-6d	47	93
15	Sm(OTf)3	EA	(Sp)-6c	99d	95

^aReactions were carried with 7b (0.10 mmol), [Ru(p-cymene)I₂]₂ (0.5 mol%), (S_p)-6 (10 mol%), Lewis acid (20 mol%), solvent (2 mL), H₂ (800 psi), 50 °C, and 22 h; Na₂CO₃ (2.0 equiv.), allyl iodide (2.0 equiv.), 18-crown-6 (15 mol%), THF (2 mL), RT, and 24 h.

^bConversion and diastereoselectivity were measured by the analysis of ¹H NMR spectra.

^cDetermined by chiral HPLC.

^dIsolated yield for the reaction with a 0.15 mmol scale and 24 h in the step of reduction.