. 2020 Mar 16;11(15):3878–3884. doi: 10.1039/d0sc00102c

Optimization of reaction conditions^a.


Entry	Solvent	Ag salt	Temp	Product	Yield
1	DCE^b	—	70 °C^c	3a	82%^d
2	Benzene^b	—	rt^c	3a	40%^d
3	THF^b	—	rt^c	3a	47%^d
4	EtOH^b	—	rt^c	3a	55%^d
5	CH₃CN^b	—	rt^c	3a	55%^d
6	DMF^b	—	rt^c	3a	54%^d
7	DCE	AgOTf	rt^e	5a	57%^f
8	DCE	AgNTf₂	rt^e	5a	66%^f
9	DCE	AgSbF₆	rt^e	5a	53%^f
10	DCE	AgBF₄	rt^e	5a	49%^f
11	Benzene^g	AgNTf₂	rt^e	5a	11%^f
12	THF^g	AgNTf₂	rt^e	5a	27%^f
13	EtOH^g	AgNTf₂	rt^e	5a	nd
14	CH₃CN^g	AgNTf₂	rt^e	5a	53%^f
15	DMF^g	AgNTf₂	rt^e	5a	nd
16	DMSO^g	AgNTf₂	rt^e	5a	nd

Unless specified, all reactions were carried out using 1a (0.5 mmol, 2.5 eq.), 2a (0.2 mmol, 1.0 eq.), CuOAc (30 mol%), Cs₂CO₃ (50 mol%), AuPPh₃Cl (10 mol%), and Ag salt (10 mol%) in a reaction tube in DCE (2 mL) at indicated temperature.

The solvent of Castro–Stephens coupling for 3a.

Temperature for the first coupling reaction.

Isolated yield of 3a.

The first coupling step was carried out at 70 °C.

Isolated yield of 5a in a purification free manner.

After filtration, the filtrate was concentrated and diluted with the indicated solvent (4 mL) for the subsequent operation.

Optimization of reaction conditionsa.

Optimization of reaction conditions^a.