Table 1 Optimization of reaction conditionsa

From: Asymmetric formal C–C bond insertion into aldehydes via copper-catalyzed diyne cyclization

View full size image

Entry

Catalyst

Reaction conditions

Yield(%)b

1

Cu(OTf)2

DCE, 30 °C, x = 2, 12 h

<1

2

CuOTf

DCE, 30 °C, x = 2, 4 h

7

3

Cu(OTf)·1/2C6H6

DCE, 30 °C, x = 2, 1.5 h

10

4

CuI

DCE, 30 °C, x = 2, 12 h

<1

5

CuTc

DCE, 30 °C, x = 2, 12 h

 <1

6

Cu(CH3CN)4BF4

DCE, 30 °C, x = 2, 1.5 h

44

7

Cu(CH3CN)4PF6

DCE, 30 °C, x = 2, 0.5 h

74

8

Cu(CH3CN)4PF6

DCE, 30 °C, x = 4, 0.5 h

80

9

Cu(CH3CN)4PF6

DCE, 60 °C, x = 4, 0.5 h

90

10

Cu(CH3CN)4PF6

DCE, 80 °C, x = 4, 0.5 h

74

11

Cu(CH3CN)4PF6

DCM, 60 °C, x = 4, 0.5 h

63

12

Cu(CH3CN)4PF6

toluene, 60 °C, x = 4, 0.5 h

70

13

none

DCE, 60 °C, x = 4, 12 h

<1

  1. aReaction conditions: 1a (0.05 mmol), 2a (0.1–0.2 mmol), catalyst (0.005 mmol), solvent (1 mL), 30 °C to 80 °C, 0.5–12 h, in vials.
  2. bDetermined by 1H NMR spectroscopy using 1,3,5-trimethoxybenzene as the internal standard. Ms = methanesulfonyl, PMP = 4-methoxyphenyl, DCE = 1,2-dichloroethane.
Back to article page