Optimization of the reaction conditions^a.

Entry	Lamp	Time (h)	Conv.b(%)
1	CFL 20 W	20	24
2	Blue 26 W	20	20
3	Green 26 W	20	10
4	CFL UVA 26 W	20	55
5	—	20	Traces
6	CFL UVA 26 W	1	12
7	CFL UVA 26 W	2	37
8	CFL UVA 26 W	4	48
9	CFL UVA 26 W	6	61
10	CFL UVA 26 W	8	50
11c	CFL UVA 26 W	6	60
12d	CFL UVA 26 W	6	55
13e	CFL UVA 26 W	6	26

^aThe reaction was performed in the presence of 1a (0.5 mmol), 2a (0.5 mmol) and pyrrolidine (20 mol%) in MeCN (1 mL).

^bDetermined by GC, based on the amount of cyclohexanone 2a.

^c20 mol% benzoic acid was added.

^d20 mol% of Bi₂O₃ was added.

^eUnder an argon atmosphere.