Table 1 Optimization of resolution of amino phenol 1a

From: Practical access to axially chiral sulfonamides and biaryl amino phenols via organocatalytic atroposelective N-alkylation

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Entry

2

Cat

Solvent

Conv. (%)b

Product, ee (%)c

1a, ee (%)c

S d

1

2a

A

CH2Cl2

30

3a, 60

26

5

2

2a

B

CH2Cl2

26

3a, −26

−9

2

3

2a

C

CH2Cl2

76

3a, −7

−23

1.4

4e

2a

D

CH2Cl2

5

3a, 73

4

6.6

5

2a

E

CH2Cl2

28

3a, 74

29

9

6e

2a

F

CH2Cl2

9

3a, 78

8

8.7

7

2a

E

CH3CN

80

3a, 22

90

4

8

2a

E

THF

28

3a, 20

8

1.6

9

2a

E

EtOAc

28

3a, 36

14

2.4

10

2a

E

1:1 CH2Cl2/CH3CN

62

3a, 50

82

7

11f

2b

E

1:1 CH2Cl2/CH3CN

60

4a, 65

98

21

12g

2b

E

1:1 CH2Cl2/CH3CN

39

4a, 86

55

23

  1. aUnless noted otherwise, the reactions were performed with 1a (0.04 mmol, 1.0 equiv.), 2 (0.8 equiv.), catalyst (20 mol%) in solvent (0.5 mL) at 24 oC for 4 h
  2. bDetermined by 1H NMR
  3. cDetermined by chiral HPLC
  4. dS = ln[(1 − Conv.)(1 − ee1a)]/ln[(1 − Conv.)(1 + ee1a)]
  5. e15 h instead of 4 h
  6. fThe reaction time was 24 h
  7. gUse of 10 mol% E and with 24 h reaction time
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