Table 1.

Optimization of reaction conditions^a

Yield (%)b
Entry	Catalyst	Co-catalyst/Oxidant	2a	3	4	5	6
1	Pd(OAc)2	Cu(OAc)2	6	trace	trace	11	7
2	Pd(OAc)2	CuI	16	trace	trace	7	trace
3c	Pd(OAc)2	Other Cu salts	<8	trace	trace	<17	<10
4	Pd(OAc)2	-	trace	trace	trace	12	5
5	-	CuI	41	trace	trace	<5	n.d.
6d	CuI	Ni salts	<39	<11	trace	<5	n.d.
7e	CuI	Fe salts	<32	<9	<12	<5	n.d.
8f	CuI	Co salts	<24	<9	trace	<5	n.d.
9	CuI	AgOAc	53	17	13	6	n.d.
10g	CuI	Other Ag salts	<51	<20	<17	<8	n.d.
11h	CuI	AgOAc	64	15	8	<5	n.d.
12i	CuI	AgOAc	76 (71)j	trace	trace	<5	n.d.
13	CuI	-	54	trace	trace	<5	n.d.
14	-	AgOAc	-	-	-	-	-
15k	CuI	AgOAc	-	-	-	-	-
16l	CuI	AgOAc	68	trace	8	<5	n.d.
17m	CuI	TBHP	73	trace	trace	<5	n.d.

TBHP tert-butyl hydroperoxide. n.d. not detected.

^aReaction conditions: 1a (0.25 mmol), Catalyst (10 mol%), Oxidant (10 mol%), and TFA (10.0 equiv) in DMSO (1 mL) under O₂ at 90 ^oC for 60 h.

^bThe yields were determined by 1H NMR using dibromomethane as the internal standard.

^cOther Cu salts see Supplementary Table 1.

^dNi salts see Supplementary Table 2.

^eFe salts see Supplementary Table 3.

^fCo salts see Supplementary Table 4.

^gOther Ag salts see Supplementary Table 5.

^h9 mol% AgOAc was used.

ⁱ50 μL H₂O was added.

^jIsolated yield is shown in parentheses.

^kWithout TFA.

^lUnder air.

^mTBHP (2.2 equiv) instead of AgOAc and O₂.