. 2022 May 23;13(24):7165–7171. doi: 10.1039/d2sc01909d

Optimization of the reaction conditions^a.


Entry	Base	Solvent	Time/h	Yield^b (%)
1	DABCO	DMSO	24	Trace
2	DBU	DMSO	24	Trace
3	K₃CO₃	DMSO	24	4
4	LiOH	DMSO	24	23
5	KOH	DMSO	24	58
6	NaOH	DMSO	24	61
7	NaOH	CH₃CN	24	15
8	NaOH	DMF	24	31
9	NaOH	Ethanol	24	Trace
10	NaOH	CH₂Cl₂	24	Trace
11^c	NaOH	DMSO	24	66
12^d	NaOH	DMSO	24	32
13^e	NaOH	DMSO	24	45
14^f	NaOH	DMSO	24	45
15^c^,^g	NaOH	DMSO	24	69
16^c^,^g^,^h	NaOH	DMSO	24	69
17^c^,^g^,^h^,ⁱ	NaOH	DMSO	24	73
18^c^,^g^,^h^,ⁱ	NaOH	DMSO	12	73
19^c^,^g^,^h^,ⁱ	NaOH	DMSO	36	73
20^c^,^g^,^h^,ⁱ^,^j	NaOH	DMSO	24	73
21^c^,^h^,ⁱ^,^j	—	DMSO	24	0
22^c^,^g^,^h^,ⁱ^,^j^,^k	NaOH	DMSO	24	23

General conditions: 1a (2.0 equiv.), 2a (0.2 mmol) and base (1.5 equiv.) in solvent (1.0 mL) were irradiated with blue LEDs (425 nm, 3 W × 2) for 24 h under an argon atmosphere at 35 °C.

Yields were determined by ¹H NMR using nitromethane as the internal standard.

1a : 2a = 4 : 1.

1a : 2a = 1 : 1.

1a : 2a = 1 : 2.

1a : 2a = 1 : 4.

NaOH (2.0 equiv.).

50.0 μL DMF was added as the co-solvent.

ⁱ

15 °C.

Air atmosphere.

In the dark.

Optimization of the reaction conditionsa.

Optimization of the reaction conditions^a.