1. Optimization of the Reaction Conditions .

entry	1	(R)-3	solvent	anti/syn,	ee (%)
1	1a	(R)-3a	toluene	60/40	96
2	1a	(R)-3a	CH2Cl2	64/36	95
3	1a	(R)-3a	THF	85/15	95
4	1a	(R)-3a	Et2O	94/6	97
5	1a	(R)-3b	Et2O	95/5	98
6	1a	(R)-3c	Et2O	91/9	98
7	1b	(R)-3a	Et2O	84/16	95
8	1b	(R)-3b	Et2O	83/17	88

^aReaction conditions: 1 (0.20 mmol), 2a (0.30 mmol, 1.5 equiv), and (R)-3 (5 mol %, 0.01 mmol) in the indicated solvent (2 mL, 0.1 M) under a nitrogen atmosphere unless otherwise specified.

^bA diastereomeric mixture of 4 was obtained quantitatively in all cases.

^cThe diastereomeric ratio was determined by ¹H NMR measurements after short path silica-gel column chromatography.

^dThe enantiomeric excess of the major anti-diastereoisomer was determined by HPLC analysis using a chiral stationary phase column.

^eA 93% ee for the syn-isomer.

^fA 60% ee for the syn-isomer.