Table 1 Reaction optimizationa

From: Selective ring expansion and C−H functionalization of azulenes

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Entry

Cat. (mol %)

Solvent

Temp. (°C)

Conv. (%)

Yield (%)b

3a

4a

1

CuCl

DCE

25

100

36

7

2

CuBr

DCE

25

80

45

9

3

CuCl2

DCE

70

100

0

0

4

CuBr2

DCE

70

100

0

0

5

Cu(OAc)2

dioxane

70

70

39

7

6

Cu(OAc)2.H2O

dioxane

70

65

38

9

7

Cu(OTf)2

dioxane

25

100

32

0

8

Cu(acac)2

dioxane

40

62

55

2

9

Cu(tfacac)2

dioxane

40

78

42

1

10

Cu(hfacac)2

dioxane

40

87

81 (78)c

0

11

Cu(hfacac)2

hexane

25

84

58

1

12

Cu(hfacac)2

toluene

25

100

64

1

13

Cu(hfacac)2

DCE

25

100

84 (82)c

0

14

Cu(hfacac)2

CHCl3

25

98

68

2

15

Cu(hfacac)2

MeCN

40

85

53

4

16

Cu(hfacac)2

DMF

40

30

6

0

17d

Cu(hfacac)2

DCE

25

100

95 (93)c

0

18d,e

Cu(hfacac)2

DCE

25

100

90

0

19d,f

AgOTf

DCE

25

100

0

74c (5)c,g

  1. aAzulene (1a, 0.2 mmol, 1.0 equiv), diazo compound (2a, 1.0 equiv), and catalyst (2.0 mol %) were used in solvent (1.0 mL, 0.1 M) under a N2 atmosphere.
  2. bNMR yield with CH2Br2 as an internal standard.
  3. cIsolated yield.
  4. dDCE (4.0 mL, 0.05 M) was used.
  5. eCatalyst (1.0 mol %) was used.
  6. f1a (2.0 equiv) and 2a (0.2 mmol, 1.0 equiv) were used.
  7. g1,3-Dialkylated product.
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