Table 1 Optimization of reaction conditions for the direct C(sp³)-H hydroxylation^a


Entry	Deviation from the standard conditions	Yield (2a + 3a, %)^b	Ratio (2a:3a)^c
1	None	90	20:1
2	Eosin Y (neutral)	71	5.6:1
3	K₂-eosin Y	84	12.5:1
4	Eosin B	68	20:1
5	Phloxine B	76	20:1
6	Erythrosine	n.d.	–
7^d	AQ	trace	–
8	PT	trace	–
9^e	TBADT	decomposed	–
10	Acetone	89	14.3:1
11	DCE	trace	–
12	MeOH	n.d.	–
13	EtOAc	86	3.6:1
14	420 nm LEDs	71	6.3:1
15	400 nm LEDs	20	1.2:1
16	385 nm LEDs	9	1:1.3
17	535 nm LEDs	n.d.	–
18	65 W CFL	n.d.	–
19	No catalyst	n.d.	–
20	No O₂	n.d.	–
21	No light	n.d.	–

^aStandard conditions: 1a (0.20 mmol), Na₂-eosin Y (7 mol%), O₂ balloon, and MeCN (10 mL) at r.t. under the irradiation of 50 W 455 nm LEDs for 12 h; then thiourea (0.24 mmol, 1.2 equiv.) and MeOH (10 mL) were added and stirred for 4 h.
^bIsolated yield.
^cDetermined by NMR analysis of the mixture of 2a and 3a after flash column chromatography.
^d420 nm LEDs were used.
^e365 nm LEDs were used.
AQ anthraquinone, PT 5,7,12,14-pentacenetetrone, TBADT tetrabutylammonium decatungstate, DCE 1,2-dichloroethane, n.d. not detected, CFL compact fluorescent lamp.

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