Table 1 Conditions optimizationa.

From: Design, development and applications of copper-catalyzed regioselective (4 + 2) annulations between diaryliodonium salts and alkynes

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Entry

Catalyst

Additive

2

Yieldb

3/4c

1

Cu(CH3CN)4PF6

Li2CO3

2a

25%

1.5/1

2

CuOTf\(\cdot\)PhH

Li2CO3

2a

48%

4/1

3

Cu(OTf)2

Li2CO3

2a

51%

1/1

4

CuTc

Li2CO3

2a

40%

3/1

5

CuI

Li2CO3

2a

45%

2/1

6

CuBr

Li2CO3

2a

55%

4/1

7

CuCl

Li2CO3

2a

57%

5/1

8

CuCl

Li2CO3

2b

73%

11/1

9

CuCl

Li2CO3

2c

23%

2/1

10

CuCl

Li2CO3

2d

64%

7/1

11

CuCl

Li2CO3

2e

65%

8/1

12

CuCl

DTBP

2b

41%

9/1

13

CuCl

K2CO3

2b

56%

10/1

14

CuCl

 

2b

78% (84%)d

12/1

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  1. aConditions: 1a (0.05 mmol), 2 (0.06 mmol), additive (0.06 mmol), catalyst (10 mol%), 5 Å MS (10 mg), anhydrous solvent (1 mL), under air, 70 °C.
  2. bThe yields of 3a were determined by crude 1H NMR using dibutyl phthalate as internal standard.
  3. cThe ratios of 3a/4a were determined by crude 1H NMR.
  4. dIsolated yield for 0.2 mmol scale reaction.
  5. The bolded values highlighted the best reaction conditions and the best reaction results.
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