Table 1 Optimization of reaction conditionsa.

From: Copper-catalyzed alkyne oxidation/Büchner-type ring-expansion to access benzo[6,7]azepino[2,3-b]quinolines and pyridine-based diones

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Entry

Cat. (x mol %)

Conditions

Yield (%)b

1

Cu(CH3CN)4PF6 (10)

DCE, 80 °C, 55 h

23

2

Cu(CH3CN)4BF4 (10)

DCE, 80 °C, 60 h

19

3

CuOTf (10)

DCE, 80 °C, 60 h

26

4

Cu(PPh3)3Br (10)

DCE, 80 °C, 72 h

<1

5

Cu(OTf)2 (10)

DCE, 80 °C, 62 h

25

6

Cu(hfacac)2 (10)

DCE, 80 °C, 48 h

37

7

Zn(OTf)2 (10)

DCE, 80 °C, 29 h

<1

8

Y(OTf)3 (10)

DCE, 80 °C, 75 h

27

9

Sc(OTf)3 (10)

DCE, 80 °C, 80 h

18

10

Cu(hfacac)2 (10)

Toluene, 80 °C, 46 h

43

11

Cu(hfacac)2 (10)

Toluene, 100 °C, 20 h

51

12

Cu(hfacac)2 (10)

Toluene, 120 °C, 9 h

58

13

Cu(hfacac)2 (20)

Toluene, 120 °C, 8 h

69

14

None

Toluene, 120 °C, 8 h

<1

15c

Cu(hfacac)2 (20)

Toluene, 120 °C, 6 h

76

  1. aReaction conditions: 1a (0.1 mmol), 2a (0.2 mmol), catalyst (5–20 mol %), 0.05 M, 80–120 °C, in vials.
  2. bMeasured by 1H NMR using diethyl phthalate as the internal standard.
  3. cUsing 4 Å molecular sieves (20 mg/0.1 mmol) as an additive.
  4. Bold text highlights the optimal reaction condition.
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