. 2019 Aug 12;10(39):9104–9108. doi: 10.1039/c9sc03245b

Table 1. Selected optimization studies ^a .


Entry	Solvent	Base	Yield ^b (%)
Entry	Solvent	Base	3aa	4a + 5a (4a : 5a)
1	HFIP	Na₃PO₄	23	45 (1 : 6)
2	ⁱPrOH	Na₃PO₄	26	8 (1 : 3)
3	DMF	Na₃PO₄	30	20 (1 : 3)
4	CH₃CN	Na₃PO₄	25	14 (1 : 2)
5	DCE	Na₃PO₄	15	24 (1 : 5)
6	Toluene	Na₃PO₄	35	Trace
7	Toluene	Na₂CO₃	30	Trace
8	Toluene	K₂CO₃	20	Trace
9	Toluene	Cs₂CO₃	25	Trace
10	Toluene	NaHCO₃	24	0
11	Toluene	KH₂PO₄	52	0
12	Toluene	^tBuOLi	72	Trace
13	Toluene	—	10	0
14 ^c	Toluene	^tBuOLi	Trace	0
15 ^c	Toluene	MesCO₂Li	71	Trace
16 ^c ^, ^d	Toluene	MesCO₂Li	78	Trace
17 ^c ^, ^e	Toluene	MesCO₂Li	40	Trace
18 ^c ^, ^d ^, ^f	Toluene	MesCO₂Li	85(82) ^g	Trace
19 ^c ^, ^d ^, ^h	Toluene	MesCO₂Li	66	Trace
20 ^c ^, ^d ^, ⁱ	Toluene	MesCO₂Li	0	0

^aReaction conditions: except where otherwise noted, all of the reactions were performed with 1a (0.1 mmol), 2a (0.2 mmol), base (0.15 mmol), MesCO₂H (0.15 mmol), and [RuCl₂(p-cymene)]₂ (5 mol%) in a solvent (1 mL) at 110 °C in air for 24 h.

^bThe yields were determined by ¹H NMR analysis of the crude product using CH₂Br₂ as the internal standard.

^cWithout MesCO₂H.

^dReaction was carried out at 120 °C.

^eReaction was carried out at 130 °C.

^f2 mL of toluene was used.

^gIsolated yield.

^h3 mL of toluene was used.

ⁱWithout [RuCl₂(p-cymene)]₂. HFIP = 1,1,1,3,3,3-hexafluoro-2-propanol. DMF = N,N-dimethylformamide. DCE = 1,2-dichloroethane. MesCO₂H = 2,4,6-trimethylbenzoic acid.

Table 1. Selected optimization studies a .

Table 1. Selected optimization studies ^a .