Table 1. Optimization of the Photocatalysed Giese Reaction between Compound 1a and 2a^a.

entry	catalyst	solvent	additive	Y (%)b	drc
1	A	DCM	HE(1)/DIPEA	50	60:40
2	A	DCM	DIPEA	25	56:44
3	A	DCM	HE(1)	0
4	B	DCM	HE(1)/DIPEA	54	65:35
5	Cd	DCM	HE(1)/TEOAe	10	62:38
6	D	DCM	HE(1)/DIPEA	86	55:45
7	D	H2O	HE(1)/DIPEA	20	50:50
8	D	EtOH	HE(1)/DIPEA	75	55:45
9	D	THF	HE(1)/DIPEA	0
10	D	Tol	HE(1)/DIPEA	0
11	D	EtOAc	HE(1)/DIPEA	trace	nd
12	D	MeCN	HE(1)/DIPEA	76	60:40
13f	D	MeCN/H2Og	HE(1)/DIPEA	97	60:40
14f	D	MeCN/H2Og	HE(2)/DIPEA	50	60:40
15f	D	MeCN/H2Og	HE(3)/DIPEA	48	60:40
16f	Dh	MeCN/H2Og	HE(1)/DIPEA	53	60:40

^aReaction conditions: compound 1a (1 eq., 0.12 mmol), compound 2a (2 eq., 0.24 mmol), DIPEA (3 equiv, 0.36 mmol), HE (2 equiv, 0.24 mmol), catalyst (5 mol %, 0.006 mmol), solvent (1 mL), and blue LED (10 W).

^bConversion and yield have been calculated by nuclear magnetic resonance (NMR) employing durene as the external standard.

^cCalculated by NMR.

^dmpg-CN = 10 mg.

^eTEOA = 1.2 mmol.

^fReaction time = 2 h.

^gMeCN/H₂O = 2:1.

^hCatalyst = 2.5 mol %.