Table 2. Catalyst structure–activity relationship studies ^a .

Entry	Metal source	Ligand	Yield (3 + 4)	rr (3 : 4)	Yield 5
1	—	—	<1%	—	<1%
2	CoBr2	—	<1%	—	<1%
3	Co(DME)Br2	—	<1%	—	<1%
4	—	i–PrPDI	<1%	—	<1%
5	CoBr2	i–PrPDI	81%	>50 : 1	<1%
6	CoBr2	MePDI	58%	>50 : 1	<1%
7	CoBr2	PhPDI	4%	—	<1%
8	CoBr2	i–PrDAD	<1%	—	<1%
9	CoBr2	i–PrIP	2%	—	<1%
10	CoBr2	Terpy	4%	—	<1%
11	CoBr2	t–BuPyBOX	<1%	—	<1%
12	CoBr2	PhPyBOX	<1%	—	<1%
13	CoBr2	PPh3 (12 mol%)	<1%	—	0%
14	FeBr2	i–PrPDI	3%	—	<1%
15	NiBr2	i–PrPDI	<1%	—	<1%

^aReaction conditions: 4-vinylcyclohexene (0.14 mmol), THF (1.0 mL), 24 h, 22 °C. Yields and ratios of regioisomers were determined by GC analysis against an internal standard.