Table 1.

Optimization of the Reaction Conditions^a

Entry	Ar	Ligand	T (°C)	x	Total yieldb	γ/αb	ee of 5a′/5ac
1	Ph	(R)-BINAP	rt	5	52%	1/1.5	45%
2	Ph	(R)-TOL-BINAP	rt	5	43%	1/1	33%
3	Ph	(R)-SEGPHOS	rt	5	42%	1/1.5	8%
4	Ph	(R)-QUINAP	rt	5	11%	1/1	40%
5	Ph	(R,R)-QUINOXP*	rt	5	48%	1.5/1	8%
6	Ph	(R)-(S)-JOSIPHOS	rt	5	51%	1/1	58%
7	Ph	(R,Rp)-TANIAPHOS	rt	5	47%	1/2	51%
8	Ph	(R,R)-Ph-BPE	rt	5	37%	1/1	14%
9	Ph	(R)-DTBM-SEGPHOS	rt	5	80%	>20/1	43%
10	2-Py	(R)-DTBM-SEGPHOS	rt	5	70%	>20/1	76%
11	2-Py	(R)-DTBM-SEGPHOS	−40	5	76%	>20/1	97%
12d	2-Py	(R)-DTBM-SEGPHOS	−40	5	79%	>20/1	97%
13d	2-Py	(R)-DTBM-SEGPHOS	−40	30	92%	>20/1	97%
14d,e	2-Py	(R)-DTBM-SEGPHOS	−40	30	98%	>20/1	97%
15d,e,f	2-Py	(R)-DTBM-SEGPHOS	−40	30	82%	>20/1	97%

HPLC, high-performance liquid chromatography; NMR, nuclear magnetic resonance

^a4/4′, 0.1 mmol; 2a, 0.2 mmol.

^bDetermined by ¹H NMR analysis of reaction crude mixture using mesitylene as an internal standard.

^cDetermined by chiral-stationary-phase HPLC analysis.

^d4. 0.2 mmol; 2a. 0.1 mmol.

^e36 h.

^fCu(CH₃CN)₄PF₆ and ligand, 3 mol %, Barton's base = 2-^tBu-1,1,3,3-tetramethylguanidine.