Table 5.

Ratio of [5]/[8] for the CuBr-catalyzed diamination of para-substituted (E)-1-phenyl-1,3-butadienes 4^a

entry	arylbutadiene (4)	[5]/[8] b
1	X = OMe, 4w	0.94
2	X = Me, 4r	0.80
3	X = Ph, 4s	0.29
4	X = H, 4d	0.37
5	X = F, 4x	0.37
6	X = Cl, 4t	0.21
7	X = Br, 4u	0.18

^aThe diamination was carried out with diene 4 (0.20 mmol), N,N-di-t-butyldiaziridinone (1) (0.24 mmol), and CuBr (0.020 mmol) in CDCl₃ (0.80 mL) in a 1.5 mL vial at 0 °C under Ar for 24 h.

^bThe ratio of [5]/[8] was determined by ¹H NMR analysis of the crude reaction mixture.