Entry

Lewis acid

Yield/%

Selectivity

2

3

1

2/3/1

1

Yb(OTf)3

4.8

0.0

79.1

5.7/0.0/94.3

2

Sm(OTf)3

1.2

0.0

76.6

1.5/0.0/98.5

3

ZnCl2

0.0

4.9

59.2

0.0/7.6/92.4

4

MgBr2

0.0

0.0

59.9

0.0/0.0/100.0

5

NiBr2

3.1

0.0

39.4

7.3/0.0/92.7

6

Ni(acac)3

0.0

0.0

86.6

0.0/0.0/100.0

7

Co(BF4)2∙6H2O

10.3

0.0

32.0

24.3/0.0/75.7

8

CoCO3

0.0

1.8

81.4

0.0/2.2/97.8

9

Co(ClO4)2∙6H2O

8.2

0.0

40.1

16.9/0.0/83.1

10

Co(NO3)2∙6H2O

1.4

30.5

29.6

4.0/13.8/82.2