Table 2 Examination of steric effect on enantioselectivitya.

From: Brønsted acid-enhanced copper-catalyzed atroposelective cycloisomerization to axially chiral arylquinolizones via dearomatization of pyridine

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Entry

R

er

Charton value

△△G≠ (kcal K−1 mol−1)b

1

OMe

88.06:11.94

0.36

1.16

2

OEt

96.0:4.0

0.48

1.85

3

Ph

96.52:3.48

0.57

1.93

4

Me

92.42:7.58

0.52

1.46

5

Et

94.02:5.98

0.56

1.60

6

nBu

95.45:4.55

0.68

1.77

7

iPr

96.66:3.34

0.76

1.96

8

Cl

18.32:81.68

0.55

0.87

9

Br

16.95:83.05

0.65

0.93

  1. aReaction conditions: 1 (0.1 mmol), CuCl (10 mol%), L1 (15 mol%), (R)-CPA (0.1 mmol), toluene (2.0 mL), 20 °C for 36 h. Yields of isolated products, er values were determined by chiral HPLC.
  2. bΔΔG≠ = RTln(er), R = 0.001986 kcal K−1 mol−1, T = 293.15 K.
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