Table 3 Condition optimization for asymmetric ring-opening reaction of SCBs with alkyne 2aa.

From: Nickel(0)-catalyzed divergent reactions of silacyclobutanes with internal alkynes

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Entry

L*

Yield (%)b

erc

Entry

L*

Yield (%)b

erc

Entry

L*

Yield (%)b

erc

1

L1-9

n.r.

–

9

L18

22

78:22

17

L26

39

80:20

2

L10

70

60:40

10

L19

18

60:40

18

L27

<5

86:14

3

L11

55

50:50

11

L20

90

85:15

19

L28

18

87.5:13.5

4

L12

37

72:28

12

L21

75

82:18

20

L29

80

88:12

5

L13

40

80:20

13

L22

80

71:19

21d

L20

88

89.5:11.5

6

L14

n.r.

–

14

L23

65

81:19

22e

L20

40

90:10

7

L15

10

78:22

15

L24

<5

93.5:6.5

23d,f

L20

90

95.5:4.5

8

L16-17

37

50:50

16

L25

n.r.

–

24d,f,g

L20

92

96:4

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  1. aReactions were performed by use of Ni(cod)2 (10 mol%), chiral ligand (L*; 10–20 mol%), 1b (0.2 mmol) and 2a (0.1 mmol) in toluene (0.1 M) at 100 °C for 24 h.
  2. bIsolated yield is given.
  3. cThe enantiomeric ratio (er) was determined by chiral HPLC on commercial columns.
  4. d60 °C for 24 h.
  5. e40 °C for 24 h.
  6. fSCB 1c was employed as the substrate.
  7. g2-MeTHF was used as the solvent.
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