Table 1.

Optimization of the reaction conditions^[a]

Entry	NHC Precursor	Photoredox Catalyst	Light Source	Yield[b] [%]
1	A	4CzIPN	Blue LEDs	trace
2	B	4CzIPN	Blue LEDs	4
3	C	4CzIPN	Blue LEDs	2
4	D	4CzIPN	Blue LEDs	3
5	E	4CzIPN	Blue LEDs	15
6	F	4CzIPN	Blue LEDs	36
7	G	4CzIPN	Blue LEDs	7
8	H	4CzIPN	Blue LEDs	11
9	F	[Ir(dF(CF3)ppy)2(dtbbpy)]PF6	Blue LEDs	32
10	F	[Ir(ppy)2(dtbbpy)]PF6	Blue LEDs	39
11	F	[Ir(ppy)2(dtbbpy)]PF6	CFL	44
12	F	[Ir(ppy)2(dtbbpy)]PF6	CFL	69[c]
13	F	[Ir(ppy)2(dtbbpy)]PF6	CFL	80(74)[d]
14	F	[Ir(ppy)2(dtbbpy)]PF6	–	0
15	–	[Ir(ppy)2(dtbbpy)]PF6	CFL	0
16	F	–	CFL	0

[a] Unless otherwise noted, all the reactions were carried out with benzoyl fluoride (0.3 mmol), styrene (0.15 mmol), CF₃SO₂Na (0.2 mmol), NHC (0.02 mmol), base (0.2 mmol), and 4CzIPN (0.002 mmol) in anhydrous CH₂Cl₂ (2 mL), irradiation with blue LEDs at room temperature for 24 h. [b] GC‐FID yield using 1,3,5‐trimethoxybenzene as an internal standard, yield of isolated product is given in parentheses. [c] 0.1 mmol of styrene was used. [d] 0.4 mmol of benzoyl fluoride was used. NHC=N‐Heterocyclic carbenes. 4CzIPN=2,4,5,6‐tetra(carbazol‐9‐yl)isophthalonitrile. CFL=compact fluorescent lamp.