Table 1.

Condition optimization^a.

Entry	1	2	Rh(II)	6	4 or 5	Yield (%)b	Ee (%)c
1	1a	2a	Rh2(OAc)4	rac-6a	4a	43	–
2	1a	2a	Rh2(OAc)4	(R)-6b	4a	37	24
3	1a	2a	Rh2(OAc)4	(R)-6c	4a	31	12
4	1a	2a	Rh2(OAc)4	(R)-6d	4a	47	26
5	1a	2a	Rh2(OAc)4	(R)-6e	4a	53	43
6	1a	2a	Rh2(OAc)4	(R)-6f	4a	39	8
7	1a	2a	Rh2(OAc)4	(R)-6g	4a	45	16
8	1a	2a	Rh2(OAc)4	(R)-6h	4a	43	24
9	1a	2a	Rh2(OAc)4	(R)-6i	4a	<5	–
10	1a	2a	Rh2(OAc)4	(R)-6j	4a	61	72
11	1a	2a	Rh2(esp)2	(R)-6j	4a	80	72
12	1a	2b	Rh2(esp)2	(R)-6j	5a	81	78
13	1b	2b	Rh2(esp)2	(R)-6j	5b	84	90
14d	1b	2b	Rh2(esp)2	(R)-6j	5b	81	94
15	1b	2b	–	(R)-6j	5b	<5	–
16	1b	2b	Rh2(esp)2	(R)-6j	5b	<5	–

^aAll reactions were run in 0.1 mmol scale of 1, 1:2:3a = 1/1/0.33.

^bIsolated yield.

^cDetermined by chiral HPLC analysis.

^dAt −10 °C.