Table 1. Condition Optimization^a.

Entry	Reaction partners	L	X	Conv of 1a (%)	Yield (%) of 3 (α:β)
1	α-1a and 2a	L1	NTf2	99	89 (1:14.8)
2		L2	NTf2	99	87 (1:19.3)
3		L2	OTf	99	98 (1:1.6)
4		L3	NTf2	99	95 (1:10.2)
5		L4	NTf2	99	86 (1:12.8)
6		L5	NTf2	99	91 (1:13.2)
7		L6	NTf2	99	91 (1:11.7)
8		L7	NTf2	99	99 (1:9.9)
9		PPh3	NTf2	99	94 (1:6.3)
10	β-1a and 2a	L2	NTf2	99	94 (4.2:1)
11	β-1a and 2b	L2	NTf2	99	97 (7.4:1)
12		L2	OMs	<5	N. D.
13		L2	OTs	<5	N. D.
14		L2	BF4	38	35 (>20:1)
15		L2	PF6	99	84 (13.1:1)
16		L2	OTf	99	98 (15.4:1)
17		PPh3	OTf	99	96 (1:2.2)
18		L8	OTf	99	98 (1:1.8)
19		L2	BArF4	99	99 (1.7:1)
20		PPh3	BArF4	86	82 (1.8:1)

^aReactions were carried out at 0.05 mmol scale. Yields and conversions (conv) were determined by ¹H NMR analysis using 1,3,5-trimethoxybenzene as the internal standard. The ratios of 3a epimers were collected by the ¹H NMR analysis of the crude reaction mixture. N. D. = not determined. Ad = 1-adamantyl. BAr^F₄ = tetrakis[3,5-bis(trifluoromethyl)phenyl]borate.