Table 1 Influence of the reaction parameters on the reactiona.

From: Regio- and enantioselective umpolung gem-difluoroallylation of hydrazones via palladium catalysis enabled by N-heterocyclic carbene ligand

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Entry

Base

Solvent

Ligand

3a/4a/5ab

Yield%b

er%c

1

LiHMDS

Toluene

SIPr·HCl

81/0/19

86

–

2

LiHMDS

Toluene

None L & Pd

0/0/100

94

–

3

LiHMDS

Toluene

PPh3

5/75/20

80

–

4

LiHMDS

Toluene

(R)-BINAPd

0/0/100

78

–

5

LiHMDS

Toluene

L1

50/0/50

48

56:44

6

LiHMDS

Toluene

L2

57/7/36

93

68.5:31.5

7

LiHMDS

Toluene

L3

50/0/50

99

90.5:9.5

8

LiHMDS

Toluene

L4

57/0/43

79

91.5:8.5

9

LiHMDS

Toluene

L5

8/0/92

98

nde

10

LiHMDS

Toluene

L6

1/0/99

98

nde

11

LiHMDS

Toluene

L7

45/0/55

75

90:10

12

LiHMDS

Toluene

L8

57/0/43

86

93.5:6.5

13

LiHMDS

DCM

L8

–

trace

–

14

LiHMDS

THF

L8

7/0/93

71

nde

15

LiHMDS

Hexane

L8

30/0/70

99

86:14

16

NaHMDS

Toluene

L8

19/0/81

84

91:9

17

KHMDS

Toluene

L8

3/0/97

67

nde

18

LDA

Toluene

L8

>99/0/<1

96

95:5

19

n-BuLi

Toluene

L8

>99/0/<1

98

94.5:5.5

20f

LDA

Toluene

L8

72/0/28

67

95.5:4.5

  1. aReaction conditions: 1a/base/2a/[Pd(C3H5)Cl]2/L = 200/200/100/2.5/5; 0.05 M of 2a.
  2. bRatio and yield of 3a/4a/5a were determined by 19F NMR of crude products with trifluoromethylbenzene as the internal standard.
  3. cer value was determined by Chiral HPLC.
  4. dBINAP = 2,2’-bis(diphenylphosphino)-1,1’-binaphthalene.
  5. eNot determined.
  6. fRan at 0 °C.
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