Table 1.

Optimization of the reaction conditions.

Entry[a]	Conditions	t [h]	Conv. of 1a [%][b]	Yield of 3a [%][b]
1	4a (2 mol%), MeOH	12	100	97 (90)[c]
2	4a (2 mol%), MeOH, Air	16	100	42
3	without 4a, MeOH	16	7	3
4	4a (2 mol%), MeOH, light bulb off	16	10	7
5[d]	4a (2 mol%), MeOH	12	70	68
6[e]	4a (2 mol%), MeOH	12	29	27

^[a]Conditions: 1a (0.2 mmol, 0.1 M in degassed solvent), 2a (1 mmol), irradiation with two 18 W LED light bulbs at room temperature.

^[b]Yield determined by GC analysis using dodecane as an internal standard unless noted.

^[c]Isolated yields shown.

^[d]One 18 W LED light, reaction tube in a 55 °C water bath.

^[e]One 18 W LED light.