Table 2. Optimization of the Temperature under the Reaction Conditions Described in Table 1^a.

entry	temperature (oC)	time (min)	yield (%)b	ee (%)c
1	25	5	99	78
2	0	5	99	82
3	–20	10	99	87
4	–40	15	99	91
5	–50	30	99	93
6	–79	80	99	92

^aMolar ratio: 13a (0.2 mmol), NCS (0.21 mmol), KF (0.4 mmol), and catalyst 5 (0.5 mol %).

^bIsolated yields.

^cThe ee values were determined by HPLC analysis using a chiral column Chiralcel OD-H.