Recovery and reuse of catalyst 11.

Entry	Time (h)	Yield (%) of 15aa,b	Recovery of 11	ee (%) in 15a
1	24	87	0.06 gc	94.8
2	24	85	0.06 gd	95.0
3	24	87	0.06 ge	93.2
4	28	88	0.05 gf	93.1
5	28	84	0.05 g	94.0

^aYields refer to the pure and isolated product.

^bThe reaction was performed at room temperature with 1 mmol of 12a, 13a, 14a and 5 mol% of 11.

^cRecovered 11 was used as a catalyst in entry 2.

^dRecovered 11 was used as a catalyst in entry 3.

^eRecovered 11 was used as a catalyst in entry 4.

^fRecovered 11 was used as a catalyst in entry 5.