Table 3.

Scope studies in [2+2] cycloadditions involving 1.

entrya	alkene	cycloadduct	time	yieldb
1	Ar = 4-MePh		1 h	86%
2	Ar = 3-MePh		2.5 h	86%
3	Ar = 2-MePh		1 h	81%
4c	Ar = Ph		1.5 h	79%
5d	Ar = 4-FPh		2.5 h	78%
6	Ar = 4-AcOPh		3 h	78%
7d	Ar = 4-(HOCH2)Ph		2.5 h	56%
8e	Ar = 4-(MeO2C)Ph		4.5 h	31%
9			2 h	87%f
10d			3.5 h	0%
11			3.5 h	67%
12d			2.5 h	48%g
13			4.5 h	0%

^aReactions were irradiated with a 20 W compact fluorescent lightbulb at −15 °C using 0.25 mol% Ru(bpm)₃(BArF)₂, 1 equiv of 1, and 2 equiv of coupling partner.

^bValues reflect the average isolated yields from two reproducible experiments. Products isolated in >10:1 d.r. unless otherwise noted.

^cAlkene 1 added over 1 h.

^dAlkene 1 added over 2 h.

^eAlkene 1 added over 4 h.

^f9:1 d.r.

^g3:1 d.r.