Table 1 Reaction condition optimisation for 1,6-conjugated additiona.

From: Diastereodivergent chiral aldehyde catalysis for asymmetric 1,6-conjugated addition and Mannich reactions

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Entry

3/4

Time (h)

Yield (%)b

dr (syn:anti)c

ee (syn/anti) (%)c

1

3a

4

49

19:81

-/33

2

4a

3

36

64:36

58/-

3

3b

1.5

39

7:93

-/72

4

3c

2

54

13:87

-/70

5

3d

2

36

14:86

-/77

6

3e

3

36

15:85

-/39

7

3f

2

54

14:86

-/45

8

3g

3

44

18:82

-/48

9

3h

2

58

11:89

-/44

10d

3d

5

64

10:90

-/96

11e

3d

67

74

10:90

-/97

12

4b

2

33

80:20

−31/-

13

4c

10

28

57:43

34/-

14

4d

3

37

62:38

60/-

15

4e

7

40

63:37

48/-

16

4f

6

48

73:27

50/-

17

4g

3

36

76:24

79/-

18f

4g

5

37

79:21

83/-

19d,f

4g

3

69

94:6

86/-

20f,g

4g

7

70

95:5

90/-

21f,g,h

4g

7

56

94:6

84/-

  1. aReaction conditions: 1a (0.1 mmol), 2a (0.2 mmol), 3 or 4 (0.02 mmol), TMG (0.1 mmol), PhCH3 (0.5 mL), at 25 oC.
  2. bIsolated yield.
  3. cDetermined by chiral HPLC.
  4. dUsing tBuOK as a base.
  5. eUsing 10 mol % 3d, 30 mol % tBuOK as base and 1 mL PhCH3 as solvent.
  6. fUsing mesitylene as a solvent.
  7. gUsing 30 mol % tBuOK as a base.
  8. hUsing 10 mol % 4g as a catalyst.
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