Table 1 Optimization of reaction conditions^a


Entry	Deviation from standard conditions	Yield (%)^b
1	None	83 (77^c)
2	PC-II instead of PC-I	29
3	PC-III instead of PC-I	31
4	PC-IV instead of PC-I	NR
5	NHC B instead of NHC A	NR
6	NHC C instead of NHC A	<5
7	NHC D instead of NHC A	45
8	NHC E instead of NHC A	NR
9	NHC F instead of NHC A	<5
10	MeCN instead of DCM	27
11	THF instead of DCM	NR
12	HAT-2–HAT-5	0–31
13	ⁿBu₄NOAc instead of K₃PO₄	36
14	Cs₂CO₃ instead of K₃PO₄	27
15	DBU instead of K₃PO₄	19
16	NaHCO₃ instead of Cs₂CO₃	30
17	K₃PO₄ instead of Cs₂CO₃	27
18	No PC	NR
19	No NHC	NR
20	No base	NR
21	No HAT	NR
22	No light	NR

NR, no reaction.
^aStandard conditions: 1a (0.3 mmol), 2a (0.6 mmol), NHC A catalyst (0.06 mmol), photocatalyst (0.003 mmol), Cs₂CO₃ (0.06 mmol), K₃PO₄ (0.06 mmol), and HAT-1 catalyst (0.06 mmol) in DCM (4 mL) were irradiated with blue LEDs under Ar at room temperature.
^bDetermined by 1H NMR spectroscopy with dibromomethane as an internal standard.
^cIsolated yield.

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