Table 1.

Reaction optimization.^a

entry	photocatalyst	variation	solvent	yield (%)b
				2a	3a
1	[Ru(bpy)3]Cl2⋅6H2O	–	CH3CN	12	0
2	[Ru(bpz)3](PF6)2	–	CH3CN	0	0
3	Ir(dFppy)3	–	CH3CN	0	0
4	Ir(ppy)3	–	CH3CN	3	25
5	[Ir(dF(CF3)ppy)2(dtbpy)]PF6	–	CH3CN	38	5
6	[Ir(dtbbpy)(ppy)2]PF6	–	CH3CN	60	11
7	TTPP	–	CH3CN	0	0
8	crystal violet	–	CH3CN	0	0
9	eosin-Y	–	CH3CN	38	0
10	[Ir(dtbbpy)(ppy)2]PF6	Cy2NMe (1 equiv)	CH3CN	14	55
11	[Ir(dtbbpy)(ppy)2]PF6	no Cy2NMe	CH3CN	0	trace
12	no catalyst	–	CH3CN	0	0
13	[Ir(dtbbpy)(ppy)2]PF6	no light	CH3CN	0	0
14	[Ir(dtbbpy)(ppy)2]PF6	–	DCM	0	16
15	[Ir(dtbbpy)(ppy)2]PF6	–	DMF	72 (71)	7
16	[Ir(dtbbpy)(ppy)2]PF6	–	DCE	22	11
17	[Ir(dtbbpy)(ppy)2]PF6	–	DMSO	37	6
18	[Ir(dtbbpy)(ppy)2]PF6	–	dioxane	50	13
19	[Ir(dtbbpy)(ppy)2]PF6	–	TFE	0	20
20	[Ir(dtbbpy)(ppy)2]PF6	–	acetone	22	trace
21	[Ir(dtbbpy)(ppy)2]PF6	–	EtOAc	36	8
22	[Ir(dtbbpy)(ppy)2]PF6	–	CH3OH	4	75 (75)
23	[Ir(dtbbpy)(ppy)2]PF6	–	DMF/CH3OH (1:1)	35	29
24	[Ir(dtbbpy)(ppy)2]PF6	–	DMF/H2O (1:1)	25	10
25	[Ir(dtbbpy)(ppy)2]PF6	–	CH3CN/H2O (1:1)	15	14

^aReaction conditions: 1a (0.1 mmol), under argon atmosphere. ^bThe yields were determined by ¹H NMR spectroscopy using 1,3,5-trimethoxybenzene as the internal standard, and the isolated yields are mentioned in parentheses.