Table 1 The optimization of PTC enabled enantioselective amidation through SNAra

From: Phase-transfer-catalyst enabled enantioselective C–N coupling to access chiral boron-stereogenic BODIPYs

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Entry

Catalyst

Base

Solvent

Yieldb

ee

1

PTC 1

Cs2CO3

DCM

33%

55%

2

PTC 1

Cs2CO3

PhCl

36%

62%

3

PTC 1

Cs2CO3

1,4-dioxane

63%

72%

4

PTC 1

Cs2CO3

DMF

51%

−33%

5

PTC 2

Cs2CO3

1,4-dioxane

61%

87%

6

PTC 3

Cs2CO3

1,4-dioxane

64%

87%

7

PTC 4

Cs2CO3

1,4-dioxane

72%

86%

8

PTC 5

Cs2CO3

1,4-dioxane

45%

89%

9

PTC 6

Cs2CO3

1,4-dioxane

84%

89%

10

PTC 7

Cs2CO3

1,4-dioxane

83%

88%

11

PTC 8

Cs2CO3

1,4-dioxane

75%

91%

12c

PTC 6

Cs2CO3

1,4-dioxane:DCM

79%

91%

13d

PTC 6

Cs2CO3

1,4-dioxane:DCM

82%

92%

14e

PTC 6

Cs2CO3

1,4-dioxane:DCM

83%

96%

15f

PTC 6

Cs2CO3

1,4-dioxane:DCM

72%

92%

16e

PTC 6

Na2CO3

1,4-dioxane:DCM

nr

-

17e

PTC 6

KOtBu

1,4-dioxane:DCM

74%

90%

18e

PTC 6

DBU

1,4-dioxane:DCM

11%

92%

19e

PTC 6

Et3N

1,4-dioxane:DCM

nr

-

20e

PTC 6

-

1,4-dioxane:DCM

nr

-

21e,g

PTC 6

Cs2CO3

1,4-dioxane:DCM

42%

97%

22e

-

Cs2CO3

1,4-dioxane:DCM

nr

-

  1. aReaction conditions: 1a (0.05 mmol, 1.0 equiv.), 2a (0.055 mmol, 1.1 equiv.), PTC Cat. (10 mol%), Cs2CO3 (0.10 mmol, 2.0 equiv.), solvent (0.6 mL), 30 °C, N2, 10 h.
  2. bIsolated yield.
  3. c1,4-dioxane: DCM (0.5 mL: 0.1 mL) was used.
  4. d1,4-dioxane: DCM (0.8 mL: 0.2 mL) was used.
  5. e1,4-dioxane: DCM (0.7 mL: 0.3 mL) was used.
  6. f1,4-dioxane: DCM (0.6 mL: 0.4 mL) was used.
  7. gThe reaction was performed at 0 °C.
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