Table 1. Optimization of the Photoinduced Synthesis of β-Lactams.

entry	light source	solvent	5 (equiv)	yield 6 (%)a
1	440 nm LED	ethyl acetate	1.0	78
2	440 nm LED	toluene	1.0	90
3	440 nm LED	acetonitrile	1.0	51
4	440 nm LED	ethyl acetate	1.2	86 (72b, 86c)
5	525 nm LED	ethyl acetate	1.2	n.d.

^aYield determined by ¹H NMR using durene as the internal standard;

^bIsolated yield.

^cConducted on 1 mmol scale.