Table 1 Optimisation of reaction conditions

1

DABCO (2.0 equiv.), Et₃N (0.25 equiv.), DMA (0.4 mL)

90

90

2

DABCO (2.0 equiv.), Et₃N (0.25 equiv.)

90

87

3

DABCO (2.0 equiv.), Et₃N (0.25 equiv.), sea sand (400 mg)

90

82

4

DABCO (2.0 equiv.), Et₃N (0.25 equiv.), silica gel (400 mg)

90

43

5

DABCO (2.0 equiv.), Et₃N (0.25 equiv.), no light

90

N.R.

6

DABCO (2.0 equiv.), Et₃N (0.25 equiv.), no 4CzIPN

90

trace

7

DABCO (2.0 equiv.), Et₃N (0.25 equiv.), no NiBr₂•glyme

90

N.R.

8

DABCO (2.0 equiv.)

90

trace

9

Et₃N (0.25 equiv.)

90

38

10

none

90

N.R.

11

DABCO (1.0 equiv.), Et₃N (1.0 equiv.)

30

quant.

12

DABCO (1.0 equiv.), Et₃N (1.0 equiv.), NiCl₂•6H₂O

30

quant.

13

DABCO (1.0 equiv.), Et₃N (1.0 equiv.), NiCl₂

30

quant.

14

DABCO (1.0 equiv.), Et₃N (1.0 equiv.), NiCl₂•glyme

30

quant.

15

DABCO (1.0 equiv.), Et₃N (1.0 equiv.), NiBr₂

30

quant.

16^b

DABCO (1.0 equiv.), Et₃N (1.0 equiv.)

90

quant.

17

DABCO (1.0 equiv.), Et₃N (1.0 equiv.), 2 mmol scale

30

quant.

18

DABCO (1.0 equiv.), Et₃N (1.0 equiv.), 5 mmol scale

30

quant.

19

DABCO (1.0 equiv.), Et₃N (1.0 equiv.), 2 mmol scale, under air

30

N.R.