Table 1 Optimization of reaction conditions for the C−H bond insertion and formal C−O bond insertion^a

Entry	L	Reaction conditions	Yield (%)^b	Ratio (2a/3a)^b	Ee 2a/3a (%)^c
1	L1	DCM, 30 °C, 0.5 h	81	51/49	<5/20
2	L2	DCM, 30 °C, 0.5 h	79	80/20	65/53
3	L3	DCM, 30 °C, 0.5 h	86	49/51	22/9
4	L4	DCM, 30 °C, 0.5 h	85	78/22	68/43
5	L5	DCM, 30 °C, 0.5 h	74	86/14	55/42
6	L6	DCM, 30 °C, 0.5 h	74	86/14	71/55
7	L6	DCE, 30 °C, 0.5 h	69	61/39	71/60
8	L6	CHCl₃, 30 °C, 0.5 h	82	84/16	72/57
9	L6	DCB, 30 °C, 0.5 h	82	82/18	67/70
10	L6	CHCl₃/DCB = 1/3, 30 °C, 0.5 h	81	85/15	73/67
11	L6	CHCl₃/DCB = 1/3, 0 °C, 4 h	73	92/8	84/na
12	L6	CHCl₃/DCB = 1/3, −30 °C, 80 h	75 (73%)	99/1	92/na
13	L7	DCM, 30 °C, 0.5 h	69	14/86	46/<5
14	L8	DCM, 30 °C, 0.5 h	80	14/86	40/56
15	L9	DCM, 30 °C, 0.5 h	68	16/84	53/70
16	L10	DCM, 30 °C, 0.5 h	83	17/83	65/73
17	L10	CHCl₃, 30 °C, 0.5 h	42	34/66	63/71
18	L10	DCE, 30 °C, 0.5 h	81	18/82	63/84
19	L10	DCE, 0 °C, 7 h	84 (81%)	8/92	na/92

^aReaction conditions: 1a (0.05 mmol), Cu(CH₃CN)₄PF₆ (0.005 mmol), L (0.006 mmol), NaBAr^F₄ (0.006 mmol), solvent (1 mL), −30 °C to 30 °C, N₂, 0.5–80 h, in Schlenk tubes. ^bThe total yield and ratio of 2a and 3a were measured by ¹H NMR using 1,3,5-trimethoxybenzene as the internal standard, and the isolated yield was given within parentheses.
^cDetermined by HPLC analysis. NaBAr^F₄ = sodium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate. DCB = 1,2-dichlorobenzene.

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