Table 1 Optimization of Conditions with 1a.a

From: Atroposelective synthesis of biaxial bridged eight-membered terphenyls via a Co/SPDO-catalyzed aerobic oxidative coupling/desymmetrization of phenols

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entry

ligand

[Co]

solvent

time/h

yield (%)b

drc

ee(%)d

1

L1

Co(OAc)2

CH3CN

58

90

2.2/1

91

2

L2

Co(OAc)2

CH3CN

68

89

2.2/1

-45

3

L3

Co(OAc)2

CH3CN

80

94

2.3/1

-65

4

L4

Co(OAc)2

CH3CN

58

90

2.5/1

-90

5e

L5

Co(OAc)2

CH3CN

-

N.R.j

-

-

6

L1

CoCl2

CH3CN

-

trace

-

-

7e

L1

CoCl2

CH3CN

12

95

3.5/1

74

8e

L1

CoI2

CH3CN

-

trace

-

-

9

L1

Co(OAc)2

EtOH

60

85

1.6/1

93

10

L1

Co(OAc)2

Acetone

60

93

1.5/1

90

11f

L1

Co(OAc)2

Acetone

50

82

3.5/1

89

12g

L1

Co(OAc)2

Acetone

19

95

4.5/1

90

13h

L1

Co(OAc)2

Acetone

12

90

5/1

93

14h

L1

Co(OAc)2

Acetone/EtOH=3/1

5

91

5/1

94

15h, i

L1

Co(OAc)2

Acetone/EtOH=3/1

5

95

5/1

95

  1. aThe reaction was conducted with 1a (0.1 mmol), Co salt (10 mol%), and ligand (12 mol%) in solvent (1 mL).
  2. bYield of the isolated product.
  3. cDetermined by 1H NMR analysis.
  4. dThe ee values were determined by UPC2 or HPLC.
  5. eAt 0 °C.
  6. fPyridine (40 mol%) was added.
  7. gEt3 N (40 mol%) was added.
  8. hDABCO (1,4-diaza[2.2.2]bicyclooctane, 40 mol%) was added.
  9. iSolvent (4 mL).
  10. jN.R.: no reaction.
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