Table 1. Optimization Studies.

entrya	ligand	additive	3 (%)b	4 (%)b	5 (%)b	6 (%)b
1	PPh3		<5	30	30	25
2	PCy3		15	42	23	14
3	IMes		24	36	19	<5
4	IPr		22	<5	5	<5
5	Xantphos		30	<5	30	<5
6	DPEphos		50	24	25	<5
7	dppf		35	14	12	<5
8	dppe		11	<5	<5	<5
9	dppp		40	18	20	<5
10	dcpe		25	16	12	<5
11	dcpe*c		60	<5	<5	15
12	dcpe	P(O)Ph3	72	<5	<5	8
13	dcped		35	<5	<5	<5
14			<5	30	22	<5
15		P(O)Ph3	<5	8	6	<5
16e	dcpe	P(O)Ph3	60	<5	<5	10
17f	dcpe	P(O)Ph3	23	28	30	15

^aReactions run on a 0.3 mmol scale. Diastereomeric ratio of 3 >95:5 in all cases.

^bDetermined by ¹H NMR analysis using 1,3,5-trimethoxybenzene as the internal standard.

^cdcpe* = dcpe:dcpe(O):dcpe(O)₂ in a 3:1:3 ratio.

^d12 mol %.

^eNaO^tBu used instead of LiO^tBu.

^fNaOMe used instead of LiO^tBu.