Optimization of the reaction conditions^a.

Entry	Solvent	Yield (%)
1	MeCN	90
2	DCE	61
3	DMC	86
4	PC	Trace
5	H2O	80
6	2-CH3-THF	42
7	EG	19
8	TBME	57
9	PEG-200	Trace
10	PEG-400	Trace
11	H2O : EtOH (v/v = 1 : 1)	77
12	H2O : EtOH (v/v = 2 : 1)	70
13	H2O : MeOH (v/v = 1 : 1)	78
14	H2O : MeOH (v/v = 2 : 1)	72
15	H2O : THF (v/v = 1 : 1)	61
16	H2O : THF (v/v = 2 : 1)	68
17b	H2O	N.D.
18c	H2O	N.D.
19d	H2O	74

^aReaction conditions: 1a (0.2 mmol), 2a (0.4 mmol), PIDA (0.4 mmol), solvent (2 mL) under air for 8 h, rt, 430 nm Blue LED (5 W). N.D. = Not detected. Isolated yields were given. DCE = 1,2-dichloroethane, DMC = dimethyl carbonate. TBME = tert-butyl methyl ether, EG = ethylene glycol, PC = propylene carbonate.

^bWithout PIDA.

^cExperiment performed in the dark.

^dReaction under N₂ atmosphere.