Table 1 Optimization of the reaction conditions

From: Enantioselective construction of inherently chiral pillar[5]arenes via palladium-catalysed Suzuki–Miyaura cross-coupling

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Entry

[M] (mol%)

Ligand

Base

T (°C)

Solvent

Time (h)

Yield of 3a (%)a

Ee of 3a (%)b

1

Pd(OAc)2 (10)

L7

K2HPO4

90

TBME

12

10

86

2

Pd(OAc)2 (10)

L7

Na2CO3

90

TBME

12

trace

-

3

Pd(OAc)2 (10)

L7

K2CO3

90

TBME

12

25

62

4

Pd(OAc)2 (10)

L7

Cs2CO3

90

TBME

12

70

86

5

Pd(OAc)2 (10)

L7

Cs2CO3

90

Toluene

12

nr

-

6

Pd(OAc)2 (10)

L7

Cs2CO3

90

THF

12

15

80

7

Pd(OAc)2 (10)

L7

Cs2CO3

90

1,4-dioxane

12

trace

88

8

Pd(OAc)2 (10)

L7

Cs2CO3

90

Et2O

12

10

37

9

Pd(TFA)2 (10)

L7

Cs2CO3

90

TBME

12

72

88

10

Pd2(dba)3 (5)

L7

Cs2CO3

90

TBME

12

65

88

11

Pd(acac)2 (10)

L7

Cs2CO3

90

TBME

12

35

81

12

[Pd(allyl)Cl]2 (5)

L7

Cs2CO3

90

TBME

12

82

90

13

[Pd(allyl)Cl]2 (5)

L7

Cs2CO3

70

TBME

12

73

91

14

[Pd(allyl)Cl]2 (5)

L10

Cs2CO3

70

TBME

12

75

96

15

[Pd(allyl)Cl]2 (5)

L10

Cs2CO3

70

TBME

24

88(85)c

96

  1. Unless otherwise specified, the reaction conditions were as follows: 1a (0.10 mmol), 2a (0.50 mmol), 5–10 mol% [Pd], 12 mol% ligand, and 5.0 equiv. of base in 3.0 mL of solvent at 70–90 °C for 12–24 h under nitrogen. The bold part represents the chiral ligand.
  2. aDetermined by 1H-NMR analysis.
  3. bDetermined by chiral HPLC analysis.
  4. cIsolated yield.
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