Table 2 Asymmetric Friedel-Crafts reaction of N-sulfonyl aldimines with indolea

From: Permanent porous hydrogen-bonded frameworks with two types of Brønsted acid sites for heterogeneous asymmetric catalysis

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Entry

Cat.

R

Yield (%)b

ee (%)c

1

(R)-1-Ni

4-H

92

91 (R)

2

 

4-Br

95

97 (R)

3

 

4-F

96

94 (R)

4

 

4-Cl

96

98 (R)

5

 

4-CF3

93

99 (R)

6

 

4-Me

89

90 (R)

7

 

2-NO2

99

97 (R)

8

 

2-Me

89

99.7 (R)

9

 

3-Br

92

99.6 (R)

10

(R)-1-Ni*/Me4Ld

4-H

87 (93)

88 (86) (R)

11

 

4-Br

90 (95)

95 (95) (R)

12

 

4-Me

80 (92)

88 (86) (R)

  1. aReaction conditions: N-sulfonyl aldimine (0.1 mmol), indole (0.3 mmol), and (R)-1-Ni (0.04 mol% catalyst based on N-sulfonyl aldimine) in DCE (1 mL), 0 °C, 10 h
  2. bIsolated yield
  3. cDetermined by HPLC
  4. dCatalyzed by 0.03 mol% of the discrete (R)-1-Ni and 0.24 mol% of (R)-Me4L
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