Table 1. Optimization Studies.

entry	Conditions	4 yield (%)a	e.e. (%)
1	Ligand L1, L2 or L3	<5	–
2	Ligand L4	44	20
3	Ligand L5	33	30
4	Ligand L6	72	40
5	Ligand L7	49	64
6	Ligand L8	45	74
7	Ligand L9	>95	90
8	L9, EtOAc instead of Et2O	80	84
9	L9, MTBE instead of Et2O	89	89
10	L9, Toluene instead of Et2O	91	91
11b	L9, 0.40 mmol of 1	>95	94

^aNMR yields.

^bReaction performed using 1.25 mol % of Pd₂(dba)₃·CHCl₃ and 3.5 mol % of (S,S)-ligand.